What is a colonoscopy?

Colonoscopies are used to detect changes or abnormalities in the lining of your colon and rectum — abnormalities that can result in colorectal cancer over time.

In the US, regular colonoscopy screening starts at age 45, and should be done every 10 years. If you have a higher risk of developing CRC or have recently finished treatment for CRC, these recommendations will be different, so it important to follow the screening advice of your doctor. We will talk more about this later on!

During a colonoscopy, a doctor looks at your intestines with a colonoscope. This is a flexible tube about the width of a finger, with a light and small video camera on the end. It is inserted through the anus, and into the rectum and colon. If your doctor sees anything concerning, they can use special instruments to remove it if small, or take a biopsy (tissue sample) for analysis. 

How do I prepare for a colonoscopy?

Before your colonoscopy, you will need to empty out your colon. Poop can obscure the view of your intestinal walls, meaning your doctor can’t get a good look at the lining of your colon & rectum.

Typically, you will be asked to avoid certain foods, like nuts and seeds for several days before the procedure. Then you will be put on a liquid diet the day before the exam. This means you can only drink clear liquids — plain water, tea and coffee without milk, broth, and carbonated beverages. Don’t drink or eat anything after midnight the day before the exam.

Then, you will take a “bowel prep.” This contains laxatives that help clear the colon and rectum. Speak to your physician about what they specifically recommend. It is very important that you follow the bowel prep instructions carefully or the procedure may have to be repeated.

Discuss your medications with your doctor — especially if you have diabetes, high blood pressure, or heart problems. Tell your doctor if you take aspirin, medications that thin the blood, or contain iron. Your healthcare team will advise you if you need to pause or adjust your medication doses.

What should I do on colonoscopy day?

Arrive at your appointment early. Make sure you get directions ahead of time! Because you will be receiving sedation, you will need to arrange for someone to drop you off and pick you up from your appointment. When you arrive, you will register at the front desk then be asked to change into a gown. 

You will likely be given a sedative. Sometimes the sedative is combined with pain medication to minimize any discomfort. Many patients will be under what is called “twilight sedation” where you will be able to respond to the doctor’s questions, but you will not remember much after the procedure. You will have an opportunity to speak with the doctor before your procedure. 

What happens during the colonoscopy?

The procedure typically takes 30-60 minutes.

The doctor will ask you to lay on your left side on the exam table, with your knees drawn towards your chest. Then, the colonoscope will be inserted in your anus, through your rectum, and into your colon. You may feel some pressure while this is happening, but the sedatives should prevent you from feeling pain or remembering this later. If you feel uncomfortable during the procedure, let the technician know.

The scope contains a tube that allows the doctor to pump air or carbon dioxide into your intestines. This inflates your colon, making it easier to see what’s going on. Being pumped full of air might be uncomfortable — you might feel abdominal cramping or the urge to go to the bathroom.

If the doctor sees anything concerning, they will take a biopsy. Smaller polyps may be removed during the procedure — and if they are, your report will tell you. The sedative will prevent you from feeling any pain during the procedure.

What happens after the colonoscopy?

It will likely take you about an hour to start recovering from the sedative. Make sure you have organized someone to pick you up from the procedure, because it can take up to 24 hours for the sedative to fully wear off. Remember to not drive or go back to work that day.

If a polyp was removed during the procedure, your doctor may advise you to temporarily eat a special diet. 

For a few hours after the exam, you’ll likely feel bloated and farty as you expel the air used in the exam. Don’t worry, this feeling will dissipate quickly. Walking around can help speed up the process!

When you go to the bathroom, you might notice a small amount of blood. This is normal. If you continue to pass blood or blood clots, have persistent abdominal pain, or a fever, contact your doctor. 

How do I get my results and what do they mean?

Your doctor will tell you what they found during the colonoscopy after you recover from sedation. Usually, you’ll be given a report that tells you what was done and the findings of the colonoscopy. If a biopsy was taken or polyps were removed, they will be submitted to pathology for examination. Once results are available, they’ll appear on your patient portal. Your doctor may call you to discuss.

If the colonoscopy was all clear or normal, that means the doctor didn’t find any abnormalities in your rectum or colon. You will likely be asked to come back for another colonoscopy in 10 years if you’re at average risk of colorectal cancer, in 5 years if you have a history of polyps or a family history of CRC, or in 1 year if the doctor could not get a good look at your colon.

If you have recently finished treatment for colorectal cancer, you will need more frequent colonoscopies for the first few years following your treatment. Your doctor will give you recommendations based on your individual diagnosis and risk factors.

If the colonoscopy was not all clear, this means the doctor found polyps or other abnormal tissue. Most polyps aren’t cancerous, but some can be precancerous. You may be asked to come back for a repeat colonoscopy. Please make sure to ask what the results mean for you — because a predisposition for polyps may indicate an increased risk for CRC in your family. So make sure to ask if there is any information that needs to be shared with your family.

How often do I need to get a colonoscopy?

If you are in the US, routine screening for colon cancer begins at age 45. Colonoscopies are then recommended every ten years for screening. People with additional risk factors will need to have them more often, approximately every five years.

If you have been diagnosed with colorectal cancer and have had germline/genetic testing done, the report will provide screening recommendations for your immediate family members. Read them carefully and make sure that you understand them, as they may be different from recommendations for the general population.

If you have been diagnosed with stage I, II or III CRC, you will need to get a colonoscopy one year after your surgery. If the results are normal, then you will come back again after three years, and every five years after that. If polyps are found, then patients are asked to return in a year.

If you have been diagnosed with stage IV CRC and reach NED (no evidence of disease) status, the recommendations are similar. Here are the surveillance recommendations for colonoscopies from the NCCN patient guidelines for colon and rectal cancer.

How useful are colonoscopies?

If the bowel prep didn’t clear your colon and rectum out well, your doctor might not be able to get a good look. They may recommend a repeat colonoscopy, or other exams to image your intestines.

Colonoscopies are highly accurate at detecting CRC, but are not perfect. Overall, this procedure can capture 94% of all colorectal cancer.

COLONTOWN University has so much more to offer, from DocTalk videos with CRC experts to easy-to-understand biomarker test breakdowns. We’re here for you! See our list of Learning Centers here.

Last updated: May 18, 2022

All About Scans And Imaging

What is imaging?

From diagnosis to treatment to disease surveillance, imaging tests are routinely used for monitoring colorectal cancer.

At diagnosis, scans will help your doctor determine the stage of your cancer, and whether or not it has spread to other organs.

Throughout your treatment journey, scans will assist your care team in determining next steps.

Following cancer treatment, scans are used to periodically screen for cancer recurrance.

Some common imaging tests include:

How often are scans done?

The frequency and schedule of imaging tests are based on the stage of your cancer, location of the primary tumor, as well as where you are in treatment.

For example, early stage CRC patients (stages I-III) will usually get a CT and MRI scan at diagnosis to ensure the cancer hasn’t spread to distant organs.

Once a patient completes treatment, the frequency and schedule of scans depends on your stage. There are specific surveillance guidelines in the NCCN guidelines.

For US patients with metastatic CRC, CT scans are usually done every 3 to 4 months. If your doctors can’t get enough information from a CT scan alone — for example, if they’re having trouble differentiating scar tissue from a possible new metastatic tumor — PET scans are used. Your healthcare team will work with you to determine when scans are needed.

Once you complete treatment — or have no evidence of disease (NED) — your scan frequency will likely be similar to when you were in treatment. As your time with NED increases, scans may be further spread out.

COLONTOWN University has so much more to offer, from DocTalk videos with CRC experts to easy-to-understand biomarker test breakdowns. We’re here for you! See our list of Learning Centers here.

Last updated: May 18, 2022

What is a PET scan?

A positron emission tomography (PET) scan is used to visualize and measure changes in the blood flow, metabolism, and chemical composition of your body. It uses a special dye containing radioactive sugar (fluorodeoxyglucose, or FDG) to image the body.

Like we said earlier, PET scans detect metabolic activity. Because cancer cells consume more energy than healthy cells, they consume the radioactive tracer in higher amounts — causing them to light up on the scan! A PET scan is usually combined with a CT scan, so the lit up area can be layered on top of your body. This is so we know where the tumor is! This type of scan help determine whether a smaller spot is cancerous or benign, as cancerous lesions are much more likely to light up on a PET scan than benign spots or scar tissue. 

Here’s what a PET machine looks like:

What do I need to do before the scan?

Your doctor will provide you with specific instructions. Typically, you’ll be asked not to eat or drink anything except water on the day of the scan. You might also be asked to avoid strenuous exercise for 24 hours before your scan.

What happens on scan day?

Arrive at the test center a bit early. When you get there, you will register with the front desk, then be taken to a dressing area. You should remove all your jewelry and clothing, and put on a hospital gown. You will also be asked to sign some consent forms, outlining the minimal risks of PET scans.

Then, the technician will explain the procedure. First, you will be asked to drink a dye, followed by in intravenous (IV) injection of a radioactive form of sugar (fluorodeoxyglucose, also known as FDG). The IV will typically be placed in your arm. After the IV, you’ll be asked to sit or lie still for about 45 minutes. This allows the dye to distribute through your body.

The technician will likely ask if you’ve ever had an allergic reaction to the dye used. It’s important to notify the technician if you have any metal in your body.

What happens during the scan?

A PET scan takes between 30 and 45 minutes, and is completely painless.

During a PET scan, patients lie flat on a narrow table sticking out of a doughnut-shaped machine. The table will move, sliding you through the machine.

The technician will give you various directions from a cubicle next to the scan room, such as when to hold your breath or stay completely still. You’ll be able to hear the technician, and the technician will be able to hear you. If you need help with anything, just ask!

It’s very important that you stay very still during the scan, so the images don’t come out blurry.

If you are claustrophobic, you can request a sedative — but this is usually not needed.

What happens after the scan?

It’s a good idea to drink plenty of water following a scan with contrast, to help your body get rid of the dye. Depending on the type of dye used, you might be advised to avoid close contact with kids, pregnant women, or pets for about 8 hours after the scan. Ask your technician if this applies to you.

Your PET scan report should be available within a few days. It will be sent to your oncologist and uploaded to your patient portal, if you have one. Your oncologist will discuss the results with you at your next appointment.

You should also request a CD copy of your scan photos for your records. Place this copy in a safe space. Some hospitals have a $5 charge for them, but they are legally obligated to provide you with a copy.

How often do I need to get a PET scan?

This will depend on your individual circumstances. PET scans are usually ordered when your doctor suspects mestastases, or when a patient has rising CEA levels but clear CT scans. In these situations, a PET/CT scan can help find areas with metastatic cancer.

Oncologists will use different types of surveillance scans (CT, MRI or PET) depending on what they think is the best way to monitor your cancer. So you’ll likely get a variety of scans at different points in your treatment. 

In fact, PET scans are used much less frequently than CT and MRI scans for surveillance. Many patients will have a CT and/or MRI scan initially, and only be given a PET scan if there’s something your oncologist wants to see in greater detail.

How useful are PET scans?

PET scans are used to detect metabolically active areas in your body — so cancer shows up. PET scans can detect smaller tumors than CT or MRI scans, although they can’t reliably detect tumors smaller than a centimeter. Also, small tumors in the peritoneum can be very difficult to detect with most scanning technologies. Areas of inflammation can also show up on PET scans. 

If your doctor is unsure of the results of a PET scan, they’ll likely order another test to get a better look.

Should I be concerned about radiation exposure?

When you have a PET scan, a radioactive tracer is injected into your veins. This exposes you to radiation, which can cause DNA damage — and in rare cases, increase your chances of developing a secondary cancer.

That said, the amount of radiation exposure is relatively low, and the benefits of being able to accurately monitor your cancer far outweigh the risks. However, it’s a good idea to speak with your team about your concerns. They may be able to recommend an alternative screening test, or clarify the risks and benefits. It’s always important to follow your oncologist’s screening recommendations to make sure you’re receiving the best care possible.

COLONTOWN University has so much more to offer, from DocTalk videos with CRC experts to easy-to-understand biomarker test breakdowns. We’re here for you! See our list of Learning Centers here.

Last updated: May 18, 2022

Conquering scanxiety

Do you feel stressed out before a scan? Do you feel anxious waiting for results? This is what cancer patients, thrivers, and survivors call “scanxiety.” Scans can be physically uncomfortable, and you may find yourself fearing the worst about your cancer — but there are ways to help.

First off, let’s talk about how scanxiety can affect you.

Stress can release adrenaline, telling your brain to go into fight or flight mode. This can lead to an increased heart rate, sweating, feeling shaky — or even nausea or muscle pain. Scanxiety can cause emotional effects too. You might find yourself reliving how you felt during your diagnosis, or other scary moments in your life.

Tips for managing scanxiety

Figure out what stress looks like for you

Everyone reacts to stress a little differently. Some people might get sweaty hands or an upset stomach. Maybe you have trouble sleeping. Other people find themselves easily irritated and don’t know why. Figuring out how you respond can help you spot signs of stress, and take steps to relieve them.

Find some distractions

Read a book, watch TV, go for a walk, listen to music or a podcast. Find ways to take your mind off upcoming scans. 

Plan something fun

Give yourself something to look forward to. Even if it’s as simple as getting a cup of coffee and a doughnut, or a trip to the library to get some new books, plan something that you can get excited about after your scan.

Meditate

Meditation might sound intimidating, but it’s easier than you’d think. Sit down someplace comfortable and quiet, close your eyes, and focus on your surroundings. What can you feel beneath you? What can you hear? What does the air smell like? Then, focus on your breathing. Listen to yourself breathe in and out. Remember that meditation is a practice — you don’t have to do it perfectly. Just practice clearing your mind.

Use relaxation techniques

Deep breathing exercises can help calm your heart rate and relieve anxiety. Breathe in for 5 seconds, then breathe out for 5 seconds. Repeat until you feel calmer. Or try visualization, where you imagine a calming place — the library, a beach, or even your childhood bedroom. 

Some cancer centers offer workshops on relaxation techniques. Reach out to yours to find out more.

Find your mantra

Compile a list of quotes that speak to you — kind words from your friends or family, or maybe a line from your favorite book. Having words of encouragement at hand can give you something to focus on and provide comfort.

Acknowledge your feelings

It’s okay to worry. Acknowledging that it’s normal to be nervous can help you stop stressing out over feeling stressed. You can write your feelings down in a journal, talk to a therapist, or even your pet.

Set time limits for worrying

Although it might seem counterproductive, giving yourself time to worry can help relieve some of the pressure. Set aside 10 minutes or so, and let yourself worry about your tests. During this time, think about potential outcomes — both positive and negative — but also create action plans detailing how you will address each scenario. 

You might find that you can get the nervousness out of your system, and you might feel a bit lighter afterwards. 

Stay in the present

Remember that you can’t predict the future, and it’s important to live in the present. Focus on your surroundings, and be fully engaged in what you’re doing right now. Make every moment count!

Join a support group

Many cancer centers offer support groups for patients. Reach out to your center to see what options are available to you. Join the COLONTOWN community, and connect with people who are going through the same thing as you.

Reach out to family and friends

If you have loved ones who help calm you down, spend time with them. You might even ask them to come to your appointment with you.

Schedule your appointments early in the morning

If you find yourself stressing out about scans, schedule your appointments as early as possible. You’ll get the hard part over with quickly, so you can enjoy the rest of your day. 

Make your scan as comfortable as possible

Talk to your healthcare team about what to expect. Bring a blanket or eye mask if that will help you be comfortable. Scans might be loud, so bring headphones so you can drown out the noise with your favorite music. If your scan involves needles, or anything else that might be painful, ask for numbing cream or pain medication.

Plan for getting your results

Speak to your doctor about keeping the wait for your results as short as possible. Discuss how you’d like to receive them — a phone call, email, uploaded to your patient portal or in-person appointment. This can help reduce the number of unknowns related to your scan. 

COLONTOWN University has so much more to offer, from DocTalk videos with CRC experts to easy-to-understand biomarker test breakdowns. We’re here for you! See our list of Learning Centers here.

Last updated: May 18, 2022

What is an MRI?

A magnetic resonance imaging (MRI) scan uses a very strong magnetic field, as well as radio waves, to create a detailed image of your organs and tissues.

MRIs are a good choice when doctors need to look at a particular area, especially soft tissues (tissue that surrounds your internal organs and bones). These scans are able to pick up smaller lesions in the liver and pelvic region that might be missed on CT scans. They can also show more detail than a CT scan. MRIs are also the most common choice for brain scans.

MRIs may not be the best choice for someone who is very claustrophobic, as they take much longer than CT scans. MRIs might also be a problem for people with metal implants in their bodies, as they can heat up and cause discomfort during scans. This is mainly a problem for older devices, as newer ones are designed to be compatible with MRI technology.

Here’s what an MRI machine looks like:

What do I need to do before the scan?

You probably won’t need to prepare much for an MRI — but chat with your doctor about any specific instructions they might have. In most cases, you will be able to take all your medications and eat and drink as usual. If you are sensitive to loud noises, bring a pair of earplugs!

What happens on scan day?

Arrive at the test center a bit early. When you get there, you’ll register with the front desk. Then you’ll be taken to a dressing area, where you should remove all jewelry and clothing, and put on a hospital gown. You will be asked to sign some consent forms outlining the minimal risks of MRI scans.

Then, the technician will explain the procedure. If you’re having a contrast MRI, they will place an IV. The IV will typically be put in your arm, but in some cases they will use your port, if you have one.

The technician will ask you if you’ve ever had an allergic reaction to the contrast dye used. It’s important to let them know if you have any metal implants in your body.

What happens during the scan?

An MRI takes between 20 and 90 minutes, and is completely painless.

During an MRI, you’ll lie flat on a narrow table sticking out of a doughnut-shaped machine. The table will move, sliding you through the machine.

If you receive IV contrast, you will likely feel a warm flush sensation in your groin area. It’s possible the technician will place a hard white plastic coil around the part of your body being scanned. The coil works as a radio receiver to help improve the images. They may also use molds or immobilization devices to keep certain parts of your body still. These devices should not feel uncomfortable! Let the technician know if they are.

The technician will give you directions from a cubicle next to the scan room — such as when to hold your breath or stay completely still. You will be able to hear the technician, and the technician will be able to hear you. If you need help with anything, just ask!

Some patients find it helpful to close their eyes when going into the machine. If you are feeling claustrophobic, you can request a sedative — but this is usually not needed.

You’ll likely feel air from the fans as the table moves. The MRI machine often makes thumping noises. This is caused by the magnetic fields the machine uses. If the technician approves them, you can use earplugs to muffle the sound. 

What happens after the scan?

It’s a good idea to drink plenty of water following a scan with contrast, to help your body get rid of the dye. 

Your MRI scan report should be available within a few days. It will be sent to your oncologist and uploaded to your patient portal, if you have one. Your oncologist will discuss the results with you at your next appointment.

You should also request a CD copy of your scan photos for your records. Place this copy in a safe space. Some hospitals have a $5 charge for them, but they are legally obligated to provide you with a copy.

How often do I need to get an MRI?

It depends on your individual circumstances. MRIs are not routinely used in the US, but they are sometimes ordered if your oncologist wants to take a closer look at a concerning area found on a CT scan.

Oncologists will use different types of surveillance scans (CT, MRI or PET) depending on what they think is the best way to monitor your cancer. So you’ll likely get a variety of scans at different points in your treatment. 

How useful are MRIs?

MRIs are considered very good imaging tools to look at soft tissue. Most CRC patients will get a pelvic MRI at diagnosis to rule out metastases in the pelvis. For rectal cancer, MRIs are very useful for staging and to assess how the cancer has affected lymph nodes. MRIs are also very useful for looking at liver metastases. Although an MRI shows more detail than a CT scan, peritoneal metastases can be very difficult to detect with most imaging techniques.

If your doctor is unsure of the results of an MRI, they’ll likely order another test to get a better look.

Should I be concerned about radiation exposure?

No. MRI scans do not use ionizing radiation like CT scans. Instead, they use magnetic fields and radio waves to take pictures of your body.

COLONTOWN University has so much more to offer, from DocTalk videos with CRC experts to easy-to-understand biomarker test breakdowns. We’re here for you! See our list of Learning Centers here.

Last updated: May 18, 2022

What is a CT scan?

Computed tomography (CT) scans are one of the primary tools doctors use while diagnosing, treating, and following up with colorectal cancer patients. 

A CT scan uses a thin beam of radiation to create images of the inside of your body from various angles. The technician will take many different images, which are then combined by a computer to make one detailed 3D picture.

CT scans can be done much more quickly than MRI or PET scans — so they’re often a good choice when doctors need to get a general idea of what’s going on throughout the entire body. They’re also a good choice for people who are claustrophobic, as MRI scans take much longer to complete. They may also be a good choice for people that have metal implants in their bodies, as some of these implants may be incompatible with MRI machines. The disadvantage is that CT scans use radiation. Your care team will decide how frequently you should get CT scans.

Here’s what a CT machine looks like:

What do I need to do before the scan?

Some patients may be asked to drink an oral contrast, which is a type of dye that allows the radiologist to see your abdomen better. If you have oral contrast, you’ll be asked to stop eating for a specific time before the CT scan. If you have a cold sensitivity, you can ask for your oral contrast without ice! Some patients might feel some stomach discomfort and may need to use the restroom.

If you are having a non-contrast CT scan, or a scan with IV contrast, you will not need to prepare much. If you receive IV contrast, you may need bloodwork done before you receive it. This is to make sure your kidneys are working well, because the dye can affect kidney function.

What happens on scan day?

If you are getting oral contrast, you’ll be asked to arrive about 90 minutes early. When you get there, you’ll register with the front desk and receive your contrast. They’ll ask you to finish drinking it within a specific time frame.

Then, you’ll be taken to a dressing area. You should remove all your jewelry and clothing, and put on a hospital gown. You’ll also be asked to sign some consent forms, outlining the minimal risks of CT scans.

Then, the technician will explain the procedure. If you’re having a contrast CT, they will place an IV. The IV will typically be put in your arm, but in some cases they will use your port (if you have one!). The technician will likely ask you if you’ve ever had an allergic reaction to the contrast dye used.

What happens during the scan?

A CT scan takes less than 15 minutes, and is completely painless.

During the scan, patients lie flat on a narrow table sticking out of a doughnut-shaped machine. The table will move, sliding you through the machine.

The technician will run you through the procedure. If you receive IV contrast, you might feel a warm flush sensation in your groin area. Making sure you’re well hydrated can reduce this sensation! The technician will then give you various directions from a cubicle next to the scan room — such as asking you to hold your breath or stay completely still. You’ll be able to hear the technician, and they will be able to hear you, so if you need help with anything just ask.

What happens after the scan?

It’s a good idea to drink plenty of water following a scan with contrast, to help your body get rid of the dye.

Your scan report should be available within a few days. This will be sent to your doctor and uploaded to your online patient portal, if you have one. If you receive your results before you have an appointment with your care team, it’s a good idea to wait to hear from them before trying to interpret the results by yourself. 

You should also request a CD copy of your scan photos for your records. Place this copy in a safe space. Some hospitals have a $5 charge for them, but they are legally obligated to provide you with a copy.

How often do I need to get a CT scan?

This will depend on your individual circumstances. If you have metastatic CRC and are receiving chemo, immunotherapy, or targeted therapies, scans are usually ordered every 3 months in the US. This is to make sure you’re responding well to treatment. 

If you have finished treatment, and are NED (no evidence of disease), patients who had metastatic CRC might have scans every 3 to 4 months. If you had early stage CRC, scans might be more spread out — such as once every 6 to 12 months initially, then annually for 5 more years.

Oncologists will use different types of surveillance scans (CT, MRI or PET) depending on what they think is the best way to monitor your cancer. So you’ll likely get a variety of scans at different points in your treatment.

How useful are CT scans?

CT scans are very useful for identifying the status of your cancer. CT results — along with other imaging and blood tests — help your care team understand how you are responding to therapy or how you are doing during surveillance.

As with any other test, CT scans have detection limits. Results depend on the size, type, and extent of metastases — as well as many other factors. For example, having scar tissue from previous surgeries! 

It’s important to note that CT scans can miss peritoneal metastases, especially in people with mucionous tumors. CT has also been proven less effective at diagnosing cancer than a PET scan, but CT is often used over PET due to cost differences — and to avoid frequent exposure to the radioactive dye used in PET scans. 

But in general, CT scans are very reliable. If your doctor is unsure of the results of a CT scan, they’ll likely order another test (such as an MRI or PET scan) to get a better look.

Should I be worried about radiation exposure from frequent CT scans?

CT scans expose patients to ionizing radiation, which can damage DNA. In rare cases, this can cause a secondary cancer. 

Depending on the part of the body being scanned, a CT scan exposes you to 1 to 10 millisieverts (mSv), the unit that scientists use to measure radiation exposure.

Each year, the average person is exposed to approximately 3 mSv from the environment. If you are having regular CT scans, you’ll be exposed to more radiation than the average person.

But don’t worry! The amount of radiation exposure is relatively low, and the benefits of being able to accurately monitor your cancer far outweigh the risks. The chances of developing cancer as a result of your CT scans is very low (approximately 1 in 2000). The risks are higher in children and younger adults than for adults over 60 years old. 

With metastatic CRC, patients often get CT scans every 3-4 months. This can add up to a lot of scans over time! PET scans use radioactive tracers, so this also adds to your exposure.

If you have concerns about radiation exposure, it’s a good idea to keep track of the dates and types of scans you’ve had throughout your treatment. Talk to your oncologist about any concerns you have. They might be able to recommend an alternative screening method like an MRI, which does not use radiation. However, they are usually much more expensive than a CT scan.

COLONTOWN University has so much more to offer, from DocTalk videos with CRC experts to easy-to-understand biomarker test breakdowns. We’re here for you! See our list of Learning Centers here.

Last updated: March 20, 2023

What tests might be useful for me?

These are some of the tests, scans and procedures commonly done in the United States. It’s important to note that this structure might not be followed in other countries.

If you are a stage I patient:

At diagnosis

  • Colonoscopy
  • Ct scan of chest, abdomen, pelvis
  • MRI of pelvis
  • CEA testing
  • Tumor biopsy testing for MSS/MSI-H and BRAF status
  • ctDNA testing through tests such as Guardant REVEAL (optional)

If you’ve had surgery

  • Tumor testing for MSS/MSI-H and BRAF status, if not done before
  • ctDNA testing through tests such as Signatera (if pre-treatment tissue samples are available)

For surveillance

  • Routine bloodwork
  • CEA testing
  • CT scan
  • Colonoscopy
  • ctDNA testing done through Signatera (if pre-treatment tissue samples are available) or Guardant REVEAL

If you later have an enlarged lymph node or suspected spot on an organ

  • ctDNA testing done through Signatera (if pre-treatment tissue samples are available) or Guardant REVEAL
  • PET or CT scan (or MRI, if the spot is on the liver)

If you are a stage II patient:

At diagnosis

  • Colonoscopy
  • CT scan of chest, abdomen, pelvis
  • MRI of pelvis
  • CEA testing
  • Tumor biopsy testing for MSS/MSI-H and BRAF status
  • ctDNA testing through tests such as Guardant REVEAL

If you’ve had surgery

  • Tumor testing for MSS/MSI-H and BRAF status, if not done before
  • Immunoscore testing of tumor tissue
  • ctDNA testing through tests such as Signatera (if pre-treatment tissue samples are available) or Guardant REVEAL. This can help your care team decide if chemotherapy is necessary, and if so, how long the treatment should be

For surveillance

  • Routine bloodwork
  • CEA testing
  • CT scan
  • Colonoscopy
  • ctDNA testing done through Signatera (if pre-treatment tissue samples are available) or Guardant REVEAL

If you later have an enlarged lymph node or suspected spot on an organ

  • ctDNA testing done through Signatera (if pre-treatment tissue samples are available) or Guardant REVEAL
  • PET or CT scan (or MRI, if the spot is on the liver)

If you are a stage III patient:

At diagnosis

  • Colonoscopy
  • CT scan of chest, abdomen, pelvis
  • MRI of pelvis
  • CEA testing
  • Tumor biopsy testing for MSS/MSI-H and BRAF status
  • ctDNA testing through tests such as Guardant REVEAL

If you’ve had surgery

  • Tumor testing for MSS/MSI-H and BRAF status, if not done before
  • Immunoscore testing of tumor tissue
  • ctDNA testing through tests such as Signatera (if pre-treatment tissue samples are available) or Guardant REVEAL. This can help your care team decide how long your chemotherapy regimen should be

For surveillance

  • Routine bloodwork
  • CEA testing
  • CT scan
  • Colonoscopy
  • ctDNA testing done through Signatera (if pre-treatment tissue samples are available) or Guardant REVEAL

If you later have an enlarged lymph node or suspected spot on an organ

  • ctDNA testing done through Signatera (if pre-treatment tissue samples are available) or Guardant REVEAL
  • PET or CT scan (or MRI, if the spot is on the liver)

At progression

  • Liquid biopsies such as Guardant360, Guardant360 CDx, or Foundation One Liquid
  • Tumor genomic testing through extended genomic panels, such as Foundation One, Tempus, or Caris

If you are a stage IV patient:

  • Colonoscopy
  • Ct scan of chest, abdomen, pelvis
  • MRI of pelvis
  • CEA testing
  • Tumor biopsy testing for MSS/MSI-H and BRAF status
  • Tumor genomic testing through extended genomic panels, such as Foundation One, Tempus, or Caris
  • Liquid biopsy tests such as Foundation One Liquid
  • ctDNA testing through tests such as Guardant360

On chemotherapy

  • Routine blood tests
  • CEA testing
  • CA 19-9 if CEA is not a good biomarker for you
  • CT scan
  • ctDNA testing done through Signatera (if pre-treatment tissue samples are available)

On regimens that include targeted therapies (herceptin, vectibix, erbitux, BRAF inhibitor, MEKi, immunotherapy)

  • Routine blood tests
  • CEA testing
  • CA 19-9 if CEA is not a good biomarker for you
  • CT scan
  • Liquid biopsies such as Guardant360, Guardant360 CDx, or Foundation One Liquid

At progression

  • ctDNA testing done through Signatera (if pre-treatment tissue samples are available) or Guardant360
  • Tumor genomic testing through extended genomic panels, such as Foundation One, Tempus, or Caris

For surveillance

  • Routine blood tests
  • CEA testing
  • CA 19-9 if CEA is not a good biomarker for you
  • CT scan
  • ctDNA testing done through Signatera (if pre-treatment tissue samples are available) or Guardant360

Want to chat with other patients going through the same thing?

Join one of our COLONTOWN Facebook groups:

  • 1st Avenue (Stage I patients)
  • 2nd Avenue (Stage II patients)
  • 3rd Lane (Stage III patients)
  • Four Corners (Stage IV patients)
  • NEDS Ballroom (Patients with current or past NED — no evidence of disease — status)

Interested in joining? Fill out the registration form here.

COLONTOWN University has so much more to offer, from DocTalk videos with CRC experts to easy-to-understand biomarker test breakdowns. We’re here for you! See our list of Learning Centers here.

Last updated: May 18, 2022