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What is Colorectal Cancer?

Colorectal cancer is cancer that forms in the colon or rectum. The colon (the biggest part of the large intestine) and the rectum are part of the digestive system. They help remove solid waste from the body. Sometimes colorectal cancer is called colon cancer or rectal cancer because of where it starts, but the two cancers are often lumped together because their treatments are similar. Most colorectal cancers start when growths that can form on the inner lining of the colon or rectum (polyps) change over time.

Colorectal cancer is the fourth most commonly diagnosed cancer in the U.S. It used to be more common, but rates have gone down as more people have routine colorectal cancer screenings. Some of these screening tests, like colonoscopy, let doctors remove polyps before they can develop into cancer.

The American Cancer Society recommends screening start at age 45 for people with average risk. The U.S. Preventive Services Task Force recommends screening starting at age 50.

Risk Factors

The risk of colorectal cancer increases with age. Colorectal cancer is much more common after age 50.

Some of the risk factors for colorectal are lifestyle factors that it may be possible for you to change. These include:

  • Obesity
  • Little or no physical activity
  • Moderate to heavy alcohol use
  • Smoking
  • Eating a lot of red or processed meat
  • Not getting enough calcium
  • Not eating enough whole grains, fruit and vegetables.

Other risk factors you have no control over. These include:

  • A personal history of polyps in the colon
  • Family history of colorectal cancer and/or polyps
  • A personal history of ovarian cancer, endometrial cancer (cancer in the lining of the uterus), or breast cancer
  • Chronic inflammatory bowel disease (ulcerative colitis or Crohn’s dis­ease)
  • Type 2 diabetes
  • Inherited genetic conditions, such as familial adenomatous polyposis (FAP) and Lynch syndrome. Lynch syndrome is the most common inherited form of colorectal cancer. This is also known as hereditary nonpolyposis colorectal cancer (HNPCC). It accounts for about 2% to 4% of all colorectal cancers.

Having an inherited genetic condition or a family history of colorectal cancer affects the age you should begin screening, the type of screening you receive, and how often you are screened.

Signs and Symptoms

Many people with colorectal cancer have no symptoms at all. That’s because symptoms often only begin to occur when the cancer is more advanced.
Possible signs of colorectal cancer include: 

  • Blood (either bright red or very dark) in the stool 
  • Change in bowel habits 
  • Constant tiredness or anemia 
  • Diarrhea, constipation, or feeling that the bowel does not empty completely 
  • General abdominal discomfort (frequent gas pains, bloating, fullness, or cramps) 
  • Stools that are narrower than usual 
  • Vomiting 
  • Weight loss with no known reason 

If you have these symptoms, it is important to see your doctor for a physical examination, blood tests and a colonoscopy.

Diagnosis

To diagnose colorectal cancer, your doctor will likely give you the following tests:

Physical Exam: During the exam, your doctor will look for tenderness, swelling, or unusual growths in your rectum. Your doctor will also check the rest of your body to look for signs of spread to other sites and to evaluate your overall health.

Colonoscopy: Your doctor may want to look at your full colon. This will require a colonoscopy. Your doctor will tell you how to prepare at home the night before this screening. During the colonoscopy, your doctor will insert a camera on a long, flexible tube through your anus and rectum and into your colon to look at it. They also will remove any polyps and take samples of (biopsy) any other abnormal-looking tissue from your colon. Another doctor called a pathologist will look at the samples under a microscope to search for cancer.

Blood Tests: Your doctor will ask for a complete blood count (CBC) to get a picture of your overall health. The CBC shows information about your red blood cell count. Because many people with colorectal cancer lose blood in their stool, even if they cannot see it, your red blood count may be low and you may be anemic. Your doctor can treat that to help you feel stronger and less tired.

Your blood can also be tested for biomarkers, substances made by cancer cells. The most common biomarkers for colorectal cancer are CEA (carcinoembryonic antigen) and CA 19-9. Your doctor may want to test your blood for these biomarkers before starting treatment and then again during treatment to see if it is working. These tests are typically ordered only after diagnosis to follow the disease.

Imaging Studies: These tests allow your doctor to see if the cancer has spread to other parts of the body. You may have a CT scan of your chest, abdomen, and pelvis. Your doctor may also request MRI scans. If you have rectal cancer, you may have an endoscopic ultrasound test. Chest X-rays and PET scans are not routinely used for colorectal cancer. But your doctor may order them if they want to get more information about potential spread of the cancer.

Biomarker Testing of Your Tumor Tissue: Your doctor may test your tumor tissue removed during a biopsy or surgery for biomarkers. These tests can help your doctors understand which treatments are right for you and whether your cancer is inherited.

  • All colorectal cancer patients should ask their doctor if they have been tested for MSI-High (microsatellite instability) or dMMR (DNA mismatch repair) status. If you test MSI-High, your doctor may give you an additional test to see if your cancer is inherited (meaning you have Lynch syndrome).
  • If you test positive for PIK3CA (PI3 kinase), you may benefit from taking aspirin after colorectal cancer surgery.
  • Patients with advanced or metastatic colorectal cancer should ask their doctor if they have been tested for KRAS, NRAS, and BRAF. These tests help your doctor decide which treatments are most likely to work for you.

Surgery: Your final diagnosis and cancer stage may not be known until after you have surgery. During the surgery, the surgeon will remove the tumor itself, as well as tissue around the tumor (called margins) and fat and lymph nodes attached to the area where the tumor was found. A pathologist will look at the tissue that was removed during surgery to help determine the stage of the cancer.

Staging

A cancer’s “stage” is a measure of how far it has spread. The stage of colorectal cancer depends on three factors:

  • Tumor: How far the tumor extends from the inner lining of the colon through the layers of its walls. 
  • Nodes: Whether cancer cells are found in the lymph nodes near the site of the cancer and how many nodes are affected. Lymph nodes are small, bean-shaped structures found throughout the body. They filter substances in a fluid called lymph and help fight infection and disease. 
  • Metastasis: Whether cancer has spread beyond the colon and its nearby tissues to distant organs like the lungs, liver, bones, or brain. 

Colon and rectal cancers have similar but not identical definitions of staging:

Colon Cancer 

Stage 0: The cancer is found only in the inner lining of the colon.

Stage I: The cancer has spread to the middle layers of the colon wall.

Stage II:

  • Stage IIA: Cancer has grown into the outer layer of the colon but has not gone through it. 
  • Stage IIB: The cancer has grown through the wall of the colon or rectum but has not grown into other nearby tissues or organs. It has not spread to the neighboring lymph nodes. 

Stage III: 

  • Stage IIIA: Cancer has spread to the middle layers of the colon wall and has spread to as many as 3 lymph nodes. OR Cancer has not yet spread to the middle layer of the colon wall but involved 4-6 lymph nodes. 
  • Stage IIIB: Cancer has spread to as many as 3 nearby lymph nodes. It also has spread to the outer layers of the colon wall into nearby fat or organs or through the peritoneum. (The peritoneum is a thin membrane that lines the inside of the abdomen.) 
  • Stage IIIC: Cancer has spread to 4 or more nearby lymph nodes. It also has spread to or beyond the outer of the colon wall or to nearby fat or organs through the peritoneum. 

Stage IV: The cancer may have spread to nearby lymph nodes and has spread to other parts of the body, such as the liver or lungs. Stage 4 is also called advanced, metastatic, cancer.

Rectal Cancer 

Stage 0: The cancer is found only in the inner lining of the rectum.

Stage I: The cancer has spread to the middle layers of the rectal wall. It has not spread to the outer wall of the rectum or outside of the rectum.

Stage II: 

  • Stage IIA: Cancer has grown into the outer layer of the rectum but has not gone through it. 
  • Stage IIB: The cancer has grown through the wall of the colon or rectum but has not grown into other nearby tissues or organs. It has not spread to the neighboring lymph nodes. 

Stage III: The cancer has spread to nearby lymph nodes, but it has not spread to other parts of the body.

Stage IV: The cancer may have spread to nearby lymph nodes and has spread to other parts of the body, such as the liver or lungs. Stage 4 is also called advanced, or metastatic, cancer.

Treatment & Side Effects Management

Your treatment options will depend on your cancer’s stage, the results of biomarker testing, your age, and your overall health. It is important for you and your doctor to decide together what treatment is best for you. It is also perfectly ok for you to get a second opinion from another doctor about your treatment options. Knowing that another doctor agrees with the first doctor or finding out you have other options can help you feel confident about the choices you have made.

You do not have to rush to make a decision about your treatment. Ask questions if you do not understand anything about your treatment or the terms your doctors are using. Bring someone along for support or to take notes. Also, consider asking if you can record your conversations with your doctor. It’s a lot of information to take in at one time. Having the recording will allow you to re-listen to the conversation as you consider your options. You may also want to talk to an oncology nurse. The nurse can help you understand your options and may have more time to talk though questions than your doctor does.

Surgery

Surgery is usually the first treatment for colon cancer and for some rectal cancers.

Colon 

The goal of the surgery is to remove as much of the cancer as possible. There are two main types of surgery. The first is open surgery, where the surgeon makes a long cut in the abdomen to remove the tumor. The second is laparoscopic surgery, where the surgeon makes small cuts in the abdomen and uses a camera and small tools inserted through these cuts to perform the surgery.

Rectal

The goal of surgery is to remove as much of the cancer as possible. The doctor will try to preserve the anal sphincter (the muscle that controls bowel movements) and good bowel function. If the cancer is small and has not grown beyond the inner layers of the rectum, it may be removed through the anus. If the tumor is larger, you may need a total mesorectal excison (TME). This involves removing the rectum as well as fat, blood vessels, and lymph nodes around it in one piece. If the cancer has spread widely, you may need a larger surgery that involves removing organs such as the bladder, ovaries, cervix, or vagina. If it has not spread widely, you may be able to have sphincter-sparing surgery. Your doctor may also recommend that you have chemotherapy and radiation before surgery. This will shrink the size of the tumor and reduce the need to remove the anal sphincter. In cases where cancer has spread to or beyond outer layers of rectal wall or to the lymph nodes, combined chemotherapy and radiation (see below) are offered before surgery.

Ostomy

If your surgeon needs to bypass a large part of your colon or remove the muscle at the opening of your rectum, you will need an ostomy. This procedure makes a new path for stool and other waste by creating a stoma (opening in your abdomen) and connecting the end of your colon or small intestine to the opening. An ostomy bag that fastens to your skin over the stoma is used to collect waste.

A colostomy bypasses part of the colon. It is used more often in rectal cancer than in colon cancer. An ileostomy bypasses the entire colon and is made at the end of the small intestine (ileum). Ileostomy output is liquid. Output from a colostomy may be semi-solid or solid depending on where the ostomy is created. Some ostomies are reversible after the surgery heals and some are permanent. See our Coping with an Ostomy section.

Surgery Side Effects

After colorectal cancer surgery, a person may develop bands of scar-like tissue that form inside the abdomen. These are called abdominal adhesions. Adhesions are very common, and many people will never know they have them. However, sometimes adhesions do cause serious problems, such as intestinal obstruction or blockage. Symptoms may take months or years after surgery to occur. When they do, the most common ones are gas pains and stomach cramps. Other symptoms include abdominal pain during exercise or stretching, bloating, nausea, constipation, and vomiting. Contact your health care team right away if any of these symptoms last more than a day: waves of stomach cramps that get worse right after eating, other pain in your abdomen, or an unexplained fever. If adhesions cause complications, your doctor can treat them with surgery. Click here for more information on Side Effects.

Chemotherapy

These drugs work by killing all fast-growing cells in your body. That’s why you may lose your hair, develop nail problems, or have other side effects. Chemotherapy may be given into the vein (using an IV) or by mouth (as pills). Either way, the drugs reach almost all parts of the body. Chemotherapy given after surgery is called “adjuvant” treatment. Chemotherapy given before surgery to shrink the tumor is called “neoadjuvant” treatment.

Chemotherapy is typically given in cycles of about two to four weeks. Giving the treatment in cycles gives your body time to recover. Your treatment is likely to include alone or in combination:

  • 5-Fluorouracil or 5-FU (Carac®, Tolak®, Efudex®, and Fluoroplex®) given via IV along with the drug leucovorin (Wellcovorin®)
  • Capecitabine (Xeloda®), an oral drug that converts into 5-FU when it gets to the cancer cells
  • Irinotecan (Camptosar®), given via IV
  • Oxaliplatin (Eloxatin®), given via IV
  • Trifluridine and tipiracil (Lonsurf®), an oral drug

Chemotherapy Side Effects 

Some common side effects from chemotherapy include mouth sores, hair loss, nausea, cold sensitivity, neuropathy, diarrhea, and low white blood cell counts. Click here for more information on Side Effects. 

Chemoradiation

This treatment regimen gives you chemotherapy and radiation during the same time period. The goal of chemotherapy is to sensitize the tumor cells to radiation. Radiation is given 5 days a week for several weeks. The chemotherapy typically used is 5-FU or capecitabine (Xeoloda®). Neoadjuvant chemoradiation is given before surgery to shrink the tumor. It is used to treat locally advanced rectal cancer.

Chemoradiation Side Effects

A person undergoing chemoradiation may have side effects from chemotherapy (see above) as well as from radiation. Common side effects from radiation therapy include nausea, fatigue, and skin changes, such as redness, dryness, or itching at the site of treatment. Other side effects are specific to the part of the body being treated. Side effects can be progressive and can last after treatment is complete. Click here for more information on Side Effects.

Targeted Therapy

Targeted therapy “targets” a specific change in some cancers that help them grow, divide, and spread. Doctors decide to use it based on the findings of biomarker tests. While chemotherapy and chemoradiation can cause harm to the body’s normal cells, targeted therapy causes less harm to normal cells.

  • EGFR (epidurmal growth factor receptor) Inhibitors - Cetuximab (Erbitux®) and Panitumumab (Vectibix®). These drugs work in colorectal cancers that test negative for KRAS and NRAS mutations.

  • VEGF (vascular endothelial growth factor receptor) Inhibitors: These drugs, known as angiogenesis inhibitors, block the development of the blood vessels that cancer cells use to grow and spread. If you have metastatic colorectal cancer, your treatment options may include:

    • bevacizumab (Avastin®).and its biosimilars, bevacizumab-awwb (Mvasi®) and bevacizumab-bvzr (Zirabev®), that have also been approved by the FDA to treat advanced colorectal cancer.

    • Ziv-aflibercept (Zaltrap®) and ramucirumab (Cyramza®). Either of these drugs can be combined with FOLFIRI (5-FU with leucovorin and irinotecan) chemotherapy as a second-line treatment for metastatic colorectal cancer.

  • Kinase inhibitors - Regorafenib (Stivarga®). This drug blocks the type of proteins that help tumor cells grow and that help form new blood vessels to feed the tumors. Taken as a pill, doctors use it to treat advanced colorectal cancer when other drugs have stopped working.

Targeted Therapy Side Effects

Some of the more common side effects from targeted therapies are diarrhea and skin problems such as a rash, dry skin, or itching. The rash is often mild and is often worst within the first few weeks of treatment. Some other common side effects are fatigue; a flu-like reaction with fever and chills; bleeding; low white blood count; headache; mouth sores; loss of appetite; high blood pressure; weight loss; and abdominal pain. Click here for more information on Side Effects. 

Immunotherapy

Immunotherapy is a type of cancer treatment that uses the body’s natural defenses to identify, attack, and kill cancer cells. The immune system is designed to attack any cell it sees as unhealthy or abnormal. There are many kinds of immunotherapy treatments. They help fight cancer in three ways: They boost the immune system, “mark” cancer cells so that your immune system can better find and destroy them, and help the immune system find cancer cells and deliver treatment directly to them.

Immunotherapy treatments are effective in a small sub-set of colorectal cancer that are MSI-High or dMMR positive. The specific treatments used include:

  • PD-1 inhibitors (pembrolizumab (Keytruda®) and nivolumab (Opdivo®)). These drugs target a protein on immune cells that helps keep them from attacking other cells in the body. By blocking this protein, these drugs help the immune system fight against cancer cells.
  • CTLA-4 inhibitor (Ipilimumab (Yervoy®)). This drug blocks a different protein that keeps immune cells from attacking other cells in the body. Given through a vein (IV), it is used at the same time as the PD-1 inhibitor nivolumab (Opdivo®).

Immunotherapy Side Effects

The most common side effects of immunotherapy include flu-like symptoms (fever, chills, headache, nausea, cough, and loss of appetite), fatigue, constipation, diarrhea, skin irritations (rashes, redness, or itching), and joint pain. Most side effects can be treated early and managed well. Sometimes a side effect will occur several months later. Having one or more side effect does not always mean that you must stop taking drugs that are working for you. Click here for more information on Side Effects. 

Immunotherapy works by beefing up the immune system, which sometimes means that it attacks other parts of the body it wasn’t meant to. This can lead to serious problems, particularly if you are taking a CTLA-4 inhibitor and can be life-threatening. If you are receiving any kind of immunotherapy, it is important to let your health care team know right away if you notice any change in how you feel.

Coping with Colorectal Cancer

An important step in managing your colorectal cancer and its treatment is to be informed. Cancer is a complex and challenging disease that is treated in many different ways. The more you know about your colorectal cancer diagnosis, treatment options and possible side effects, the easier it will be to talk with your health care team to determine the best treatment plan for you. Colorectal cancer can affect all areas of your life, below is a list of resources to help with your general concerns:

It is helpful to know what the common short and long-term side effects of colorectal cancer are and how to manage them. Everyone experiences treatment and side effects differently, but it can help to feel prepared.

Coping with Ostomy

It takes time to get used to living with an ostomy, and there are a number of changes you may need to make. But after ostomy surgery, you can go on to live an active and healthy life. Below is information on coping with an ostomy:

  • Telling people about the ostomy:
    • If you don’t tell people about your ostomy and pouch, they won’t be able to tell you have it. You may need to tell your boss about it because you can’t lift heavy items, or because you need to go to the bathroom often to manage the ostomy pouch.
  • Caring for the ostomy:
    • You should change your pouch every three to seven days. If you have itching or burning, it means you should change the wafer (the part that goes against the skin and has a hole that fits around your stoma.) If you wear a pouch for too long, it may damage your skin.
  • Emergency supply kit:
    • Carry an emergency kit with supplies such as pouches, extra precut flange, roll of tape, mirror, wet wipes, and cotton swabs.
  • Showering and bathing:
    • You can bathe with or without the pouch in place. If you want to take a shower or bath with the pouch off, you can. You can leave the pouch on while bathing or cover it with plastic to keep it dry.
  • Clothing to hide the ostomy:
    • You can help hide your pouch by wearing loose-fitting tops and bottoms. You may find belts or some waistbands uncomfortable. You may want to wear clothing with higher or looser waistbands. You can buy ostomy swimsuits through specialty shops and websites.
  • Odor control: 
    • You can buy liquid and solid products to help control the odor of the pouch. Certain foods (such as asparagus, fish, garlic, and onions) can cause a stronger urine odor. You can lessen that by drinking more water or cranberry juice. Empty your pouch often. Always empty the puch before you go out of the house and away from a convenient toilet. 
  • Diet changes:
    • You may want to limit foods and drinks that cause gas. These can include asparagus, beans, beer, broccoli, Brussels sprouts, cabbage, carbonated beverages, cauliflower, onions, and peas.
  • Physical activity:
    • You can go back to most physical activity after you heal from ostomy surgery. Your doctor may advise you to stay away from contact sports, to avoid injuring the stoma. If you want to do contact sports, talk to your doctor or ostomy nurse about special products you can use, and how to protect your stoma. If you lift weights, ask your doctor when it is safe to start again. You can buy a special belt or binder to hold your ostomy bag in place for running, swimming, or other athletic activities. This can help prevent the ostomy bag from loosening and causing a leak.
  • Traveling with ostomy
    • Pack extra supplies when you travel. If you are flying, don’t pack all your supplies in the checked baggage, in case it gets lost. Limit what you eat before you travel.