When Radiation & Chemotherapy are Part of Colon Cancer Treatment

Abida Taher, MD, PhDNovember 30, 2023

Being aware of the side effects is the first step to dealing with them.

Some patients with early stage disease may also receive chemotherapy after surgery. For patients with localized colon cancer, the five-year survival rate is 90%.

Some patients who have stage 3 or higher colon cancer may need chemotherapy or radiation before surgery (called neoadjuvant treatment) to reduce the size of the tumor before surgery. This allows the surgeon to remove a smaller portion of the colon. Radiation and chemotherapy may also be part of the treatment after surgery. If cancer is found in one or more lymph nodes during surgery or there is cancer in other areas of the body, chemotherapy follows surgery.

Let's talk about radiation therapy first.

Some of the acute or subacute side effects of radiation therapy can include:

Skin irritation at the site where radiation beams were aimed, which can range from redness to blistering and peeling,
Nausea and fatigue
Rectal irritation and/or painful inflammation and rectal bleeding, which can cause diarrhea, painful bowel movements, or blood in the stool,
Bladder irritation, pain, and/or frequent urination
Problems with wound healing if radiation was given before surgery.

You will be closely monitored by your cancer care team for these side effects, and in many cases, a majority of these side effects go away after treatments are completed, but some degree of rectal and/or bladder irritation may be permanent. Radiation therapy can also cause some long-term side effects that may not show up until many months or even years after treatment. It depends on where the radiation was aimed and the dose used. These can be more serious, so you should watch for them and talk with your cancer care team about what to expect.

Long-term side effects can include:

Worsening Bowel or Bladder Irritation: This may result in a frequent need to urinate or have bowel movements, along with some pain with urination or bowel movements. Sometimes you may see blood in your urine or stool. Be sure to let your cancer care team know of these problems so that they can be addressed.
Hormonal Problems: Radiation treatment can result in premature menopause or infertility. Fertility counseling prior to treatment is recommended for women for whom this is a concern.
Vaginal Dryness: Women may have vaginal dryness and narrowing due to radiation-induced fibrosis. This can lead to pain or bleeding during sex.
Lower Sperm Count: Men may produce less semen, or their semen may have a lower sperm count, which can lower fertility. If you plan on having children, you may want to discuss saving sperm before starting radiation treatments.
Erectile Dysfunction: Radiation in the pelvic area can cause men to have trouble getting or keeping erections. There are medications or a penile pump that can help.
Bone Loss: Radiation can increase the risk of fractures in the sacral bone at the base of the spine. Your cancer care team will keep an eye on your bone density via scans to make sure you do not have fractures.

If chemotherapy will be part of your treatment it usually begins 2-4 weeks following surgery.

The chemotherapy drugs most often used in the treatment of colorectal cancer are 5-fluorouracil (5-FU), capecitabine, oxaliplatin, and irinotecan. Side effects depend on the type and dosage of drugs, the length of treatment, and individual patient characteristics. Some of the side effects are specific to certain drugs. Ask your cancer care team about the possible side effects of the specific drugs you are taking.

Some of the common expected side effects from chemotherapy for colon cancer include:

Tiredness and fatigue: It is important to take it slow during your recovery and plan to take frequent breaks as needed until you have regained some strength. Listen to your body, take naps, and rest whenever you need. Sometimes light exercises, such as going for a walk, can help raise your energy levels. Notice patterns in your chemo cycle, and try to plan activities that require a lot of energy on the days you normally feel best.

Hand-foot Syndrome: This can develop during treatment with capecitabine or 5-FU (when given as an infusion). It may present initially as redness in the hands and feet and then progress to pain and sensitivity in the palms and soles. If it worsens, the skin may blister or peel,sometimes leading to painful sores. It’s important to tell your cancer care team right away about any early symptoms, such as redness or sensitivity, so that steps can be taken to keep things from getting worse.

Cold Sensitivity and Peripheral Neuropathy: This is a common side effect of oxaliplatin. Symptoms include numbness, tingling, and pain in the hands and feet. It can also cause intense sensitivity to cold in your throat, esophagus, and palms of your hands. This can result in pain when swallowing cold liquids or holding a cold glass. If getting oxaliplatin is part of your treatment protocol, talk with your cancer care team about side effects beforehand and let them know right away if you develop numbness and tingling in your extremities.

There are some ways to lessen the severity of peripheral neuropathy. Anecdotal evidence suggests that icing can help prevent cold sensitivity caused by chemotherapy. Wearing ice-filled gloves or mittens or soaking your hands and feet in an ice bath is one way. You may be told to keep ice chips in your mouth while chemo is being given to lower the chances of getting mouth sores. It’s probably a good idea to email your cancer care team about icing beforehand to let them know about your plans.

Allergic or Sensitivity Reactions: These can happen in some people while getting the drug oxaliplatin. Symptoms can include skin rash; chest tightness and trouble breathing; back pain; or feeling dizzy, lightheaded, or weak. Be sure to tell your nurse right away if you notice any of these symptoms while you're getting chemotherapy.

Diarrhea: This is a common side effect with many of these chemo drugs but can be particularly bad with irinotecan. It needs to be treated right away—at the first loose stool—to prevent severe dehydration. Make sure you are well hydrated and eat appropriately to maintain your energy. Stay away from alcohol and caffeine. Your cancer care team will give you instructions on what medications to take and how often to take them to nip this issue as quickly as possible.

Heartburn: Many patients on capecitabine experience heartburn. Some ways to combat this are to start with small meals. If you feel fine afterwards, you can try eating a bit more. Avoid trigger foods, such as spicy foods and caffeine. Take your capecitabine pills within 30 minutes of a meal. Avoid lying down within 30 minutes of a meal. Your cancer doctor might suggest medications that can help with heartburn as well. Do not take over-the-counter antacids without consulting your cancer care team, especially Prilosec and Protonix, and Nexium should not be taken along with capecitabine.

In a majority of these cases, these side effects tend to go away over time after treatment ends.

Report any side effects or changes you notice while getting chemo so that they can be treated right away. In some cases, the doses of the chemotherapy drugs may need to be reduced, or treatment may need to be delayed or stopped to help keep the side effects from getting worse.

The most exciting change in colon cancer treatment in recent years has been immunotherapy.

Immunotherapy refers to drugs that stimulate your immune system to attack and kill cancer cells. There are several different types of immunotherapy. The most important types for advanced colorectal cancer are immune checkpoint inhibitors. They have important benefits for a small number of patients whose tumors have specific genetic alterations.

Immunotherapy-related side effects are not uncommon with immune checkpoint inhibitors. Although relatively well tolerated, common side effects include rash, colitis, liver toxicity, and lung inflammation (pneumonitis), as well as hormonal changes such as adrenal insufficiency and thyroid dysfunction. The most common side effect experienced is skin rash, which is seen in up to 30% of patients. The rash can occur anywhere on the body, even in the mucus membranes. Treatment may include moisturizing skin creams, antihistamine medications, and/or steroids. Depending on the severity of the side effect, your doctor may pause or permanently stop treatment.

The standard of care for colon cancer can be tough on your body, so having a good support system and being prepared for the common expected side effects can go a long way in easing your treatment journey.