Chemotherapy and pills

Adjuvant Chemotherapy for Colon Cancer: Who Needs It?


  • Adjuvant chemotherapy for colon cancer involves the use of drugs to kill the cancer cells that primary surgery may leave behind.
  • Adjuvant chemotherapy success rates are good, reducing the likelihood of cancer recurrence.  
  • Doctors use colon cancer chemotherapy in stage III patients.
  • Early discovery of colon cancer can help you avoid chemotherapy and its side effects. 

Adjuvant chemotherapy for colon cancer is an additional drug-based treatment some colon cancer patients undergo following primary treatment. Its purpose is to eradicate cancerous cells that may have remained after surgery. 

Doctors recommend adjuvant chemotherapy to stage III cancer patients. Sometimes, doctors may prescribe adjuvant chemotherapy to some stage II colon cancer patients. 

How Does Adjuvant Chemotherapy for Colon Cancer Work?

Doctors use chemotherapy to treat cancers. Patients who undergo chemotherapy take a cocktail of powerful chemicals that kill off the cancer cells in their bodies. Chemotherapy can be a primary treatment option or a follow-up treatment after surgery. 

Doctors may prescribe chemotherapy based on a single drug or combination of drugs. The strong chemicals in these drugs can elicit mild or serious side effects. Medical professionals have to weigh carefully to whom they prescribe chemotherapy and what combinations of drugs they use. 

Who Needs Adjuvant Chemotherapy for Colon Cancer?

Whether your doctor puts you on adjuvant chemotherapy for colorectal cancer depends on the stage of the disease. 

Stage I Colon Cancer Does Not Require Chemotherapy

Stage I colon cancer is easy to treat. It sometimes requires only a colonoscopy intervention. Early-stage colon cancer only affects the innermost lining of the colon. With no cancer cells invading the tissue surrounding the colon, including the lymph nodes, doctors don’t have to use the power of chemicals to “mop up” after a primary intervention like surgery. 

Stage II Colon Cancer Chemotherapy

Stage II colon cancer is perhaps the most challenging for doctors from the perspective of adjuvant chemotherapy. They must decide whether the benefits of chemotherapy outweigh the damage side effects may cause in stage II patients. 

For some patients, less chemotherapy is the better treatment approach. 

In stage II colon cancer, cancerous cells infect the outermost layer of the colon wall. This complicates primary treatment, although surgery alone still offers excellent outcomes

Knowing that chemotherapy may offer few benefits stacked on top of already-effective surgery makes it difficult for doctors to decide for or against it. To prescribe adjuvant chemotherapy for stage II colon cancer, doctors must first define the disease as “high risk.” High-risk stage II colon cancer fulfills the following requirements. 

  • The primary tumor is a T4. T4 is a more advanced stage II colon cancer.
  • The tumors are not well differentiated. Doctors find it more difficult to tell apart cancer cells and healthy ones in surrounding tissue.
  • Cancer has perforated the bowel.
  • Cancerous cells have invaded the lymphovascular system.
  • Bowel obstruction exists.
  • Doctors notice cancer cells at the margins of the tissue they remove during surgery. 

When these risk factors are present, according to the American Joint Committee on Cancer, the outcomes of stage II colon surgeries are worse than in T3 surgeries. 

Doctors performing surgery
Surgery is often enough for low-risk stage II colon cancers

Doctors only recommend adjuvant chemotherapy for colon cancer in high-risk cases because they know it works for stage III cancers. 

Stage III Colon Cancer Chemotherapy

Doctors routinely prescribe adjuvant chemotherapy for stage III colon cancer, given the scientific proof that supports the positive impact of chemo on survival outcomes. 

5-fluorouracil (5-FU) chemotherapy has been around since the 1990s. 5-FU-based treatments for 12 months increase patient survival odds. When combined with leucovorin, 5-FU treatments achieve similar outcomes in just six months of treatment.

Doctors use two 5-FU-based regimens: the Mayo Clinic regimen and the Roswell Park regimen. Both produce similar results, though their side effects differ somewhat.

The former tends to make patients vulnerable to infection. The latter is harder on the stomach and digestion. 

Oxaliplatin-based chemotherapy came about later, in the early 2000s. Adding these drugs to 5-FU treatments increases disease-free survival for patients. Over the last 15 years, oxaliplatin-based adjuvant chemotherapies have become the gold standard for improving stage III colorectal cancer survival rates after surgery. 

Irinotecan, anti-VEGF, and anti-EGFR antibodies do not provide better alternatives to oxaliplatin and 5-FU therapies. 

The most effective adjuvant chemotherapy regimens for stage III colon cancer are six-month courses. Researchers have been looking for ways to reduce the duration of the treatments to limit the side effects. 

Reducing the length of the therapy by three months would make it accessible to more patients. Those unfit for the six-month approach may benefit almost as much from three-month treatments. 

The Success Rate of Adjuvant Chemotherapy for Colorectal Cancer

The adjuvant chemotherapy success rate is the best in stage III patients. 

In 1990, researchers found that by combining levamisole with 5-FU, they could lower the post-surgery recurrence of colon cancer by 41 percent. At the same time, this adjuvant chemotherapy for colorectal cancer reduced overall death rates by 33 percent. 

Later research confirmed the efficacy of the approach. Doctors have found that after five years, colon cancer returned only in 1.5 percent of the patients who had received 5-FU-based adjuvant chemotherapy after surgery. The researchers also noted that cancer was most likely to return within two years of primary surgery. 

By adding oxaliplatin to chemo regimens, doctors were able to improve these results. Specifically, they improved 5-year disease-free survival by an additional 5.9 percent and 6-year disease-free survival by 2.5 percent. 

All evidence points to the effectiveness of adjuvant chemotherapy for colon cancer in preventing recurrence of disease. 

The Side Effects of Colon Cancer Chemotherapy

On the downside, chemotherapy involves the use of toxic chemicals to kill cancer cells. Over time, they can accumulate in the body, causing unpleasant side effects. Some of these side effects are short term and manageable. Others are long term and can be debilitating. 

Side effects of chemotherapy can include:

  • Loss of appetite and nausea. Many of the drugs used for adjuvant colon cancer chemotherapy can make you sick to your stomach. Your doctor may prescribe additional medication to help you with nausea. Eat smaller meals and drink plenty of liquids to avoid dehydration.
  • Changes in the frequency and consistency of your stools. Some colon cancer drugs can cause diarrhea. 
  • Abdominal pain. Colon cancer chemotherapy alters the bacteria in your gut. By upsetting the natural balance of your digestion, it can cause bloating and pain.
  • Sensitivity to cold. Colon cancer chemotherapy can damage your nerves and play tricks with your perception. While on chemo, you may experience burning sensations when you touch a cold surface.
  • Neuropathy. Cancer drugs can damage the nerves linking your spinal cord to your hands and feet. You may experience tingling sensations and numbness. Neuropathy is a long-term side-effect.
  • Increased risk of infection. Colon cancer chemotherapy does not distinguish between good cells and bad; it kills indiscriminately. It also damages the cells your immune system needs to battle infection.
  • Fatigue. Most patients on adjuvant chemotherapy for colon cancer feel exhausted. The therapy taxes the body in many ways, so fatigue is a natural reaction.  
  • Hair loss.  Not all colon cancer chemotherapy drugs cause hair loss, but most do.
  • Bruising and bleeding. Together with cancer cells, colon cancer chemotherapy also kills the cells that help make blood in your bone marrow. A lack of blood platelets makes you more likely to bleed and bruise. 
Chemotherapy side effects listed
The side effects of colon cancer chemotherapy are numerous

Early Detection is the Key to Avoiding Adjuvant Chemotherapy for Colon Cancer

Doctors agree that keeping your adjuvant chemotherapy for colon cancer as short as possible is desirable for a better quality of life. With early detection, you may be able to avoid chemo and its side effects altogether. 

Colorectal cancer screening can help you identify the problem in time and get adequate treatment that does not involve adjuvant chemotherapy.

eDrugstore Can Help

The key to the best outcome for colorectal cancer is early detection. For low- to average-risk patients, home testing is as safe and accurate as colonoscopy.

At eDrugstore, we carry at-home colorectal cancer screening kits that allow you to take a sample in five minutes, pain-free, in the comfort of your home. If your results are positive, we’ll include a free consultation with a U.S.-licensed physician to discuss next steps.

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