Chemotherapy for colon cancer: What to expect

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Doctors call very early colon cancer stage 0. Following stage 0, the stages range from 1–4, depending on how far the cancer spreads.

If colon cancer has not spread or metastasized to other body parts, a person will often have surgery as their first form of treatment. This may involve removing only the cancerous tissue, or the surgeons may need to remove nearby lymph nodes and parts of the colon, called a partial colectomy.

Doctors may use chemotherapy for about 6 months after the surgery to destroy any remaining cancer cells.

For stage 3 and 4 colon cancer, cancer may have spread to other areas, and doctors may use a combination of surgery, chemotherapy, and radiation therapy.

The American Cancer Society’s 2016–2017 report provides statistics for people receiving chemotherapy as part of their treatment. Fewer than 1% of people have chemotherapy alone for stages 1–3 colon cancer and usually also have a colectomy.

The success rate of chemotherapy for colon cancer may depend on the stage or extent of the disease.

The American Cancer Society estimates that in 2021 there will be around 104,270 new cases of colon cancer and 45,230 new cases of rectal cancer. Doctors often use chemotherapy alongside other treatments to treat colon cancer, so it is difficult to determine each treatment’s effectiveness and success rates.

The 5-year survival rate across the four stages of colon and rectal cancer is 63–67%.

Doctors may deliver chemotherapy in two ways:

Systemic chemotherapy

The individual receives the chemotherapy drugs orally or directly through a vein. The medication then enters their bloodstream and travels throughout their body.

Regional chemotherapy

Doctors administer the chemotherapy drugs via a person’s artery that leads directly to the cancer’s location. The advantage of this delivery is that lower amounts of the drug circulate throughout their body, reducing side effects.

An example of regional chemotherapy is hepatic artery infusion that doctors use for metastasized cancer or cancer that spreads to the liver.

Drugs and cycles

Doctors may use the following chemotherapy drugs for colon cancer:

• 5-fluorouracil (5-FU)
• irinotecan (Camptosar)
• oxaliplatin (Eloxatin)
• trifluridine and tipiracil (Lonsurf)
• capecitabine (Xeloda)

Individuals usually have chemotherapy drugs for colon cancer administered into a vein at the hospital, clinic, or specialist infusion center. Doctors may do this via an injection taking several minutes or an infusion over several hours.

A person receives chemotherapy in cycles followed by rest periods to allow time for recovery. Usually, cycles are 2–3 weeks long, depending on the chemotherapy drug. Doctors administer some medications only on day one of the cycles, or they may administer the drug for several days in a row or weekly. At the end of the cycle, the schedule repeats.

Doctors use neoadjuvant chemotherapy to shrink the tumor before surgery and adjuvant chemotherapy after surgery to kill any remaining cells. Adjuvant or neoadjuvant chemotherapy dosing schedules last for 3–6 months, depending on the medication.

Sometimes doctors will also use chemotherapy alongside radiation therapy. They do this around the time a person goes into the hospital for surgery or to help treat inoperable cancer.

Treatment length for advanced stages of colon cancer depends on treatment success and how well the individual is tolerating the side effects.

Chemotherapy drugs are powerful medications that kill rapidly dividing cells. As the drugs act on cancer cells, they may also kill healthy, rapidly dividing cells, including cells in the person’s bone marrow, hair follicles, and cells that line their mouth and digestive system.

When someone finishes their chemotherapy treatment, the adverse effects on healthy cells should stop.

People may experience side effects of chemotherapy, such as:

• nausea
• vomiting
• diarrhea
• mouth sores
• hair loss
• rash on the hands and feet

Bone marrow is responsible for producing blood cells. As chemotherapy may affect the bone marrow, people may also experience other side effects, including:

• low blood platelet counts, which can increase the risk of bleeding or bruising from even minor injuries
• low white blood cell counts, which could increase the risk of infection
• low red blood cell counts, leading to anemia and fatigue

Doctors have a range of treatments to treat colon cancer, and individuals will often receive a combination of approaches. The best treatment regimen may depend on the person and the stage of the tumor. Not all treatments are suitable for each individual.

Some alternatives to chemotherapy include:

Immunotherapy

Immunotherapy uses various medications to help a person’s immune system recognize and kill cancer cells. It is a relatively new form of cancer therapy that doctors may use for advanced colon cancer as an alternative to chemotherapy.

Immunotherapy medications include:

• immune checkpoint inhibitors that doctors may use for individuals with specific gene changes
• pembrolizumab (Keytruda) and nivolumab (Opdivo), PD-1 inhibitors that boost the immune response against cancer cells
• ipilimumab (Yervoy), an immune checkpoint inhibitor that also increases the immune response by blocking a specific protein on the immune cells

Radiation therapy

Radiation therapy uses high doses of radiation to kill cancer cells and reduce the size of tumors.

Doctors may use external beam therapy (EBT) to deliver high-energy X-rays or proton beams to a tumor or place a radioactive source in the individual’s body.

Doctors may use radiation in combination with surgery.

Surgery

A surgeon may remove cancerous tissues during partial colectomy surgery. Typically, they remove any tumors and a portion of normal tissue surrounding the area.

The person may need a temporary colostomy, which is an outside opening for solid waste from the bowel. A colostomy bag collects the digestive residues until the area heals. Some individuals may require colostomy permanently.

Chemotherapy is an integral part of treatment for colon cancer. Chemotherapy drugs are potent medications that target rapidly dividing cells.

Doctors typically use chemotherapy combined with surgery and radiation, making it challenging to interpret success rates for chemotherapy on its own. For stages 1, 2, and 3 colon cancer, fewer than 1% of individuals have chemotherapy as their only course of treatment.

However, whether individuals with colon cancer have chemotherapy as a stand-alone treatment or as part of a combined treatment plan, the 5-year survival rate across the four stages of colon and rectal cancer is 63–67%.