Colorectal cancer is the third most common cancer worldwide. In the United States, more than 135,000 people are diagnosed with colorectal cancer every year.

Regular screening is one of the most powerful weapons for preventing colorectal cancer. The preferred test is a colonoscopy, in which a doctor uses a thin flexible tube equipped with a camera to look for polyps—small growths—on the wall of the colon. If undiscovered and untreated, polyps can become cancerous.

Treatment for colorectal cancer often involves a combination of surgery and medication.


In approximately 80 percent of patients diagnosed with colorectal cancer, the cancer is localized (has not spread to other organs). Surgery is most often the first step in treating localized colorectal cancer. The surgeon will remove the section of the colon or rectum that contains the tumor, and will also remove nearby lymph nodes, which are small organs located throughout the body that remove waste and fluids and help fight infection.


Chemotherapy, sometimes in combination with radiation, is often given before surgery to try to shrink the tumor, making the surgery an easier process and increasing its chances of success. After surgery, cancer cells that are not detectable by tests may still exist, so doctors often suggest “adjuvant” treatment (chemotherapy given after surgery). The goal is to destroy any remaining tumor cells, decrease the chances of the cancer coming back, and reduce the risk of tumor cells spreading (metastasizing) to other parts of the body.

The chemotherapy drugs that can be used in adjuvant treatment are:

  • 5-Fluorouracil (5-FU) is given intravenously (into a vein), often with the vitamin-like drug leucovorin (folinic acid) which helps it work more effectively.
  • Capecitabine (Xeloda and others), taken in pill form, is changed by the body to 5-FU when it reaches the site of the tumor.

The intravenous (through a needle into a vein) drug oxaliplatin (Eloxatin) is sometimes given in combination with 5FU or capecitabine.

If the colorectal cancer has spread to other areas of the body, such as the liver or lungs, doctors often treat the tumor with chemotherapy alone. In addition to 5-FU and capecitabine, metastatic colorectal cancer can be treated with the intravenous drugs oxaliplatin (Eloxatin) and irinotecan (Camptosar). In September 2015, the FDA approved Lonsurf (a pill that combines two drugs, trifluridine and tipiracil) for patients with advanced colorectal cancer which is no longer responding to other therapies.

Targeted Treatments

Targeted treatments focus on specific molecules and cell mechanisms thought to be important for cancer cell survival and growth, taking advantage of what researchers have learned in recent years about how cancer cells grow. Targeted treatments are meant to spare healthy tissues and cause less severe side effects than chemotherapy.

  • VEGF inhibitors. These treatments “starve” the tumor by blocking the action of VEGF (vascular endothelial growth factor), a protein released by tumors that contributes to blood vessel growth (angiogenesis). VEGF inhibitors bevacizumab (Avastin), ramucirumab (Cyramza), and ziv-aflibercept (Zaltrap) are given intravenously, typically along with chemotherapy drugs such as oxaliplatin, irinotecan, 5-FU, and capecitabine.
  • EGFR inhibitors. EGFR (epidermal growth factor receptor) is a protein often found in high amounts on the surface of cancer cells. The targeted treatments cetuximab (Erbitux) and panitumumab (Vectibix) are designed to block the action of EGFR, preventing cancer cells from growing into tumors. These drugs are given intravenously. Some colorectal cancers have mutations (changes) in the KRAS, NRAS, or BRAF gene. For cancers with this mutation, drugs intended to block the action of EGFR are ineffective. Doctors will test the tumor for these mutations before treatment, and will not use EGFR inhibitors if the mutations are present.
  • Kinase inhibitor. Kinase proteins are substances near the surface of cells that that send important signals to the cell’s control center; by doing so, they can help tumor cells grow. The kinase inhibitor regorafenib (Stivarga), taken in pill form, is designed to help stop the growth of tumors by blocking several kinase proteins.


In immunotherapy treatment, medications are used to increase the body’s natural ability to fight cancer. Although there is much more to learn about immunotherapy in the treatment of metastatic colorectal cancer, it continues to be a promising area of research, particularly in the following areas:

  • Immune checkpoint inhibitors. Tumor cells often have “immune checkpoint” molecules that act as a shield, allowing the cancer to evade an attack by the immune system. This can be countered by immune checkpoint inhibitors—drugs designed to remove the shield and allow the immune system to attack the cancer cells. Newer drugs that target certain checkpoint molecules hold promise as treatments for colorectal cancers that have specific gene changes known as microsatellite instability (MSI).
  • Vaccines. Vaccines which boost the immune system have potential to treat colorectal cancer or prevent it from recurring (coming back) after treatment. A number of types of vaccines are being studied in clinical trials. One vaccine approach involves removing a person’s own immune system cells from their blood, altering them with a substance that will instruct them to attack cancer cells, and injecting them back into the person’s body.

Many people with colorectal cancer have tumors that do not respond to immunotherapy treatment. One of the goals of the current research is to determine how to make colorectal cancers more “immunogenic” (responsive to immunotherapy).

Personalizing Treatment: The Role of Genetic Mutations

Each tumor has its own biological makeup, based on the genes found in its cells. An important area of cancer research is understanding this biology. With this information, it’s possible for doctors to know whether a particular tumor is likely to respond to a specific treatment, allowing him or her to suggest the right treatment for each person’s tumor. This approach is known as precision (or personalized) medicine.

To better understand the biological makeup of a person’s tumor, doctors look for tumor “markers” in cell genes. Markers can predict whether a given treatment will be effective against a tumor and whether there is a high risk of the tumor coming back. Tumor markers and genetic traits are an important step on the road toward precision medicine, and they are being actively studied in clinical trials.


A key group of tumor markers that have been found in colorectal cancer are called KRAS, NRAS, and HRAS—known collectively as the RAS genes. Forty percent of people with colorectal cancer have a mutation (change) in a RAS gene. Through clinical trials, researchers have learned that these patients do not benefit from treatment with the EGFR inhibitors cetuximab and panitumumab. However, they do benefit from chemotherapy.

The other 60 percent of people with colorectal cancer have no RAS mutation; these people are said to have the RAS “wild-type” gene. These patients tend to benefit from treatment with EGFR inhibitors.

Knowing whether you have a RAS mutation or the RAS wild-type gene allows your health care team to determine the best treatment approach for your specific type of cancer.


As with RAS mutations, the majority of patients with mutations in the BRAF gene do not respond to EGFR inhibitors. Through clinical trials, doctors have learned that there are certain drugs that may be able to block this BRAF gene, which may allow patients with this mutation to respond to treatment with EGFR inhibitors. This is an active area of research, and therapies that block the BRAF gene may become available in the future.


About 4 percent of metastatic colorectal cancers have a genetic trait known as a microsatellite instability (MSI), which causes these tumors to have large numbers of genetic mutations. Immunotherapy treatment approaches are being studied in clinical trials for people with certain types of MSI tumors.

All cancer treatments can cause side effects. It’s important that you report any side effects that you experience to your health care team so they can help you manage them. Report them right away—don’t wait for your next appointment. Doing so will improve your quality of life and allow you to stick with your treatment plan. It’s important to remember that not all patients experience all side effects, and patients may experience side effects not listed here.

Side Effects of Chemotherapy

The side effects of chemotherapy depend on the type and dose of drugs given and the length of time they are used, and can include:

  • Hair loss
  • Increased risk of infection (from having too few white blood cells)
  • Easy bruising or bleeding
  • Changes in memory or thinking
  • Peripheral neuropathy (numbness or tingling in hands and feet)

Mouth sores are also a side effect of chemotherapy. Your doctor may recommend treatments such as:

  • Coating agents. These medications coat the entire lining of your mouth, forming a film to protect the sores and minimize pain.
  • Topical painkillers. These are medications that can be applied directly to your mouth sores.
  • Over-the-counter treatments. These include rinsing with baking soda or salt water, or “magic mouthwash,” a term given to a solution to treat mouth sores. Magic mouthwash usually contains at least three of these ingredients: an antibiotic, an antihistamine or local anesthetic, an antifungal, a corticosteroid, and/or an antacid.

Side Effects of Targeted Therapy

Targeted therapy drugs don’t have the same effect on the body as do chemotherapy drugs, but they can still cause side effects.

Common side effects of VEGF inhibitors include diarrhea, high blood pressure, problems with blood clotting and wound healing, low white blood cell counts (with increased risk of infections), and headaches.

The most common side effect of EGFR inhibitors is an acne-like rash on the face and chest. It can be treated by a topical antibiotic, which limits the rash and prevents infection. Other side effects can include headache, tiredness, fever, and diarrhea.

Side Effects of Immunotherapy

Immunotherapy travels through the bloodstream, helping to prompt what is called an “immune response.” Because immunotherapy can attack healthy cells as well as cancer cells, certain side effects may be experienced, including digestive tract symptoms, loss of appetite, fatigue, and flu-like symptoms.

Digestive Tract Symptoms

Nausea and vomiting

  • Avoid food with strong odors, as well as overly sweet, greasy, fried, or highly seasoned food.
  • Nibble on dry crackers or toast. These bland foods are easy on the stomach.
  • Having something in your stomach when you take medication may help ease nausea.


  • Drink plenty of water. Ask your doctor about using drinks such as Gatorade which provide electrolytes as well as liquid. Electrolytes are body salts that must stay in balance for cells to work properly.
  • Over-the-counter medicines such as loperamide (Imodium A-D and others) and prescription drugs are available for diarrhea but should be used only if necessary. If the diarrhea is bad enough that you need medicine, discuss it with your doctor or nurse.
  • Choose foods that contain soluble fiber—for example beans, oat cereals, oranges, and flaxseeds. High-pectin foods such as peaches, apples, oranges, grapefruit, bananas, and apricots can also help to avoid diarrhea.

Loss of appetite

  • To help maintain your weight, eat small meals throughout the day. That’s an easy way to take in more protein and calories. Try to include protein in every meal.
  • To keep from feeling full early, avoid liquids with meals or take only small sips (unless you need liquids to help swallow). Drink most of your liquids between meals.
  • Keep high-calorie, high-protein snacks on hand such as hard-boiled eggs, peanut butter, cheese, ice cream, granola bars, liquid nutritional supplements, puddings, nuts, canned tuna, or trail mix.
  • If you are struggling to maintain your appetite, talk to your health care team about whether appetite-building medication could be right for you.

Managing Fatigue

Fatigue (extreme tiredness not helped by sleep) is one of the most common side effects of many cancer treatments. If you are taking a medication, your doctor may lower the dose of the drug, as long as it does not make the treatment less effective. If you are experiencing fatigue, talk to your doctor about whether taking a smaller dose is right for you.

There are a number of other tips for reducing fatigue:

  • Take several short naps or breaks.
  • Take short walks or do some light exercise, if possible.
  • Try easier or shorter versions of the activities you enjoy.
  • Ask your family or friends to help you with tasks you find difficult or tiring.
  • Save your energy for things you find most important.

Managing Pain

There are a number of options for pain relief, including prescription and over-the-counter medications. It’s important to talk to a member of your health care team before taking any over-the counter medication, to determine if they are safe and will not interfere with your treatments.

As you manage your cancer, it’s important to remember that you are a consumer of health care. The best way to make decisions about health care is to educate yourself about your diagnosis and get to know the members of your health care team, including doctors, nurses, dietitians, social workers and patient navigators.

Here are some tips for improving communication with your health care team:

Start a health care journal. Having a health care journal or notebook will allow you to keep all of your health information in one place. You may want to write down the names and contact information of the members of your health care team, as well as any questions for your doctor. Keep a diary of your daily experiences with symptoms related to your illness or treatment. You can separate your journal or notebook into different sections to help keep it organized.

Prepare a list of questions. Before your next medical appointment, write down your questions and concerns. Because your doctor may have limited time, you should ask your most important questions first, and be as specific and brief as possible.

Bring someone with you to your appointments. Even if you have a journal and a prepared list of questions or concerns, it’s always helpful to have support when you go to your appointments. The person who accompanies you can serve as a second set of ears. He or she may also think of questions to ask your doctor or remember details about your symptoms or treatment that you may have forgotten.

Write down your doctor’s answers. Taking notes will help you remember your doctor’s responses, advice, and instructions. If you cannot write down the answers, ask the person who accompanies you to do that for you. If you have a mobile device, ask if you can use it to take notes. Writing notes will help you review the information later.

Remember, there is no such thing as over-communication.

Frequently Asked Questions

Q. I have been diagnosed with colorectal cancer, and I’m concerned about my children’s risk of getting the disease. What screenings or tests are recommended for them?

A. Typically, it is recommended that children undergo their first colonoscopy when they are ten years younger than their parent was at the time of their diagnosis. It is also important to know whether you have an inherited condition, such as Lynch syndrome, which increases the risk of colorectal cancer. If your colorectal cancer is possibly inherited, your children should talk to their physician about genetic screening, in addition to undergoing colonoscopies at the recommended intervals.

Q. I was recently diagnosed with colon cancer and will soon have surgery. Will I definitely need to have a colostomy as part of the surgical process?

A. A colostomy is a procedure which diverts a portion of the colon to a small opening—called a stoma— in the wall of the abdomen. The stoma is attached to a pouch, which collects stools as they exit the body. Depending on the extent of your surgery, the need for a colostomy is possible, or even likely. However, there are options that may be available to you, which you should discuss with your surgeon or another member of your health care team.

If you do require a colostomy, there is support available to help you adjust to the change in your daily routine. It can be very valuable to speak with an oncology social worker at CancerCare; consulting with an enterostomal therapy nurse (who specializes in ostomy care and rehabilitation), and joining a local support group can also be very helpful . You can also read CancerCare’s fact sheet titled, “Colostomy: Finding Resources and Support” for more information.

Q. I heard about there being differences between left-side tumors and right-side tumors. What does that mean?

A. There are biological differences in tumors depending on their location within the colon. Metastatic colorectal cancer tumors originating from the left side of the colon (the descending colon, sigmoid colon, and rectum) are associated with better outcomes than tumors originating from the right side of the colon (the cecum and ascending colon). These differences may help guide treatment approaches for people with metastatic colorectal cancer and will likely be the subject of increased focus in the coming years, as researchers seek to more deeply understand the difference in treatment options and outcomes based on the location of the tumor.

Q. Can following a ketogenic diet reduce the risk of colorectal cancer?

A. A ketogenic diet is extremely low in carbohydrates and high in certain types of fats and proteins. It encourages the body to burn fat for fuel, thereby starving the glucose system and decreasing the level of insulin in the blood. This type of diet excludes sugar, salt, and processed foods, such as hot dogs and cold cuts. There is no clinical evidence that a ketogenic diet reduces the risk of colorectal cancer, or that it is effective as part of a treatment plan for colorectal cancer. Anyone thinking of pursuing a ketogenic diet for other health reasons should first consult with a dietician or a member of their health care team.

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This booklet was supported by an educational donation provided by Amgen and an independent educational grant from Merck & Co. Inc. and Taiho Oncology Inc.

Last updated June 20, 2017

The information presented in this publication is provided for your general information only. It is not intended as medical advice and should not be relied upon as a substitute for consultations with qualified health professionals who are aware of your specific situation. We encourage you to take information and questions back to your individual health care provider as a way of creating a dialogue and partnership about your cancer and your treatment.

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