Colorectal cancer treatment (CRC)

Treatment is often classified into local therapy or systemic therapy. Local therapy means that it only treats the colon or rectum, and not any other parts of the body. Systemic therapy is treatment that goes around your entire body, treating cancer cells that may be present outside of the colon. A combination of local and systemic therapy may be given for CRC. 

This article will focus on the systemic therapy options for CRC- chemotherapy, targeted therapy, and immunotherapy.


Chemotherapy is medication that is used to stop the division of cells, causing cell death. Because cancer cells are abnormal and usually grow out of control, they are killed by chemotherapy. Unfortunately, chemotherapy can cause side effects because healthy cells are affected as well.

Chemotherapy can be given before surgery (called neoadjuvant chemo) or after surgery (adjuvant chemo). 

To treat CRC, a combination of multiple chemotherapy medications are often given. These work against the cancer cells in different ways, so that the cancer is being killed more effectively. The chemotherapy medications used most often to treat CRC include:

  • 5-fluorouracil (5-FU)
  • Oxaliplatin
  • Capecitabine (Xeloda)

If cancer has spread to other areas of the body, different chemotherapy medications may be given. 

Targeted Therapy

These medications are usually only given if colon cancer is advanced and has spread into other areas of the body. If the cancer has specific genetic mutations, such as mutations in the KRAS or BRAF genes, there may be medications available that target those genes specifically. 


Immunotherapy medications are usually intravenous medications that work by helping the immune system see any CRC cells in the body. This allows the immune system to help fight against cancer. Immunotherapy medications are most often used for advanced CRC.

Colorectal cancer

What is Colorectal cancer?

Colorectal cancer also referred to as CRC, is cancer that starts somewhere inside the colon or rectum of the digestive system. It is the third most common cancer in the United States for both men and women, and although rates of CRC overall have been decreasing, the rates have actually been going up for younger adults. 

CRC starts off by abnormal cells developing in the colon or rectum. These often start out by becoming polyps, small growths of tissue along the intestinal wall. Not all polyps will become cancer, and if they do, it can take many years for them to develop into cancer. 

Signs and Symptoms

Someone may have colon cancer and not have any signs or symptoms of it being there. This is what makes screening tests so important, so cancer can be caught before it becomes advanced. If someone does have symptoms, they may include:

  • Changes in bowel patterns (such as diarrhea or constipation)
  • Fatigue
  • Unintentional weight loss
  • Blood in the stool, or dark or tarry stool
  • Abdominal pain

Diagnostic Tests

If someone is having symptoms that may be concerning for CRC, a stool sample can be obtained to check for blood in the stool that might not be visible to the naked eye. If this test is positive, it’s likely a colonoscopy will be ordered. 

Not only are colonoscopies suggested if blood is present in the stool, but it may also be recommended to be done as a screening tool to detect colon cancer early.  During this procedure, a special camera is inserted into the rectum and moved up into the large intestine to evaluate the lining and look for any abnormalities. If a polyp or any area of abnormality is found, it can be biopsied and tested for cancer cells. A colonoscopy requires a day or so of preparation, where no solid foods are eaten, only clear liquids are to be consumed, and large amounts of laxatives are used to clean out the colon. This prep allows the gastroenterologist performing the procedure to get the best look possible at the intestinal wall. 

Once a diagnosis of CRC is made, the oncologist will likely order additional tests to learn the characteristics of the cancer. This can include molecular testing to see if there are any mutations present, such as BRAF, NRAS, or KRAS. Knowing if these mutations are present can help the oncologist come up with a treatment plan. 

Additional testing, such as CT scans or PET scans may also be done to determine if CRC has spread to any other areas of your body. Once all of the testing is complete, your oncologist can stage the cancer. 


Are you interested in learning more about colorectal cancer staging? Check out our next article on this topic.



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