Chemotherapy for colorectal cancer: cycles, timing and side effects

After surgery for colon cancer, chemotherapy is usually given for either three or six months, depending on how far the cancer had spread through the bowel wall and into the glands, and on the medicines chosen. Treatment is given in cycles, commonly every two or three weeks. Some schedules use a drip in hospital followed by a small pump that runs at home for a day or two, while others combine a hospital drip with tablets taken at home. Some people with lower-risk cancer need tablets alone, or no chemotherapy at all. For bowel cancer that has spread, cycles may continue for many months with planned breaks. Your oncologist will explain which schedule fits your reports.

Colon cancer is usually removed first, with chemotherapy after surgery if the tissue report shows it has reached the glands or has other higher-risk features. Occasionally chemotherapy is given first when the tumour is large or has grown into nearby organs. Rectal cancer, low in the bowel near the back passage, is often treated differently. Many people have chemotherapy and radiotherapy before surgery to shrink the tumour, and some receive all their chemotherapy before the operation. When the tumour shrinks a great deal, specialist teams sometimes discuss careful monitoring instead of immediate surgery. When cancer has spread to the liver, chemotherapy may be used to shrink it so the spots can be removed.

Two side effects stand out in bowel cancer chemotherapy. The first is nerve damage causing tingling, numbness or pain in the fingers and toes. With one commonly used medicine this is triggered by cold, so touching cold objects or drinking cold water can cause sharp tingling in the hands, mouth or throat for a few days after each cycle. These symptoms can build up over the course and may last after treatment ends. The second is hand-foot syndrome with tablet chemotherapy, causing red, sore, peeling palms and soles. Loose motions, mouth sores, tiredness and lowered infection resistance are also common, while hair loss is usually mild. Report worsening tingling or sore hands early.

Often three or six months

In cycles every two or three weeks after surgery.

Colon and rectum differ

Rectal cancer is often treated before surgery.

Nerves and hands are the signature effects

Cold-triggered tingling and hand-foot syndrome need early reporting.

It cannot tell you whether you need chemotherapy or which schedule is right. Your tissue report decides that.

It also cannot predict your side effects. Your team will explain what is likely with your medicines.

Higher-risk features after surgery

The tissue report describes how deeply the cancer grew, whether glands were involved, whether it had spread into vessels and whether the bowel was blocked or torn. These features, along with how many glands were examined, help your oncologist decide whether chemotherapy is advised and whether a shorter or longer course fits.

Shorter or longer courses

For some lower-risk colon cancers, a shorter course may be offered, which lowers the chance of lasting nerve damage. For higher-risk cancers, a longer course may be preferred. This is an individual decision balancing benefit and side effects, and it is worth asking your oncologist to explain the reasoning.

A tissue test for repair faults

Bowel cancers are tested for faults in genes that repair damaged DNA. Early cancers with this fault may behave differently and may not need chemotherapy in the same way. Advanced cancers with it may be offered immunotherapy. The result can also suggest an inherited condition affecting relatives.

Protecting against cold tingling

In the days after a cycle, wear gloves when handling cold items, avoid iced drinks and cold foods, cover your mouth and nose in cool air, and take care with air conditioning. These steps reduce discomfort but do not prevent nerve damage from building up over the course.

When nerve damage builds up

If tingling lasts between cycles or makes buttoning, writing or walking difficult, tell your team. They may reduce or pause the medicine responsible while continuing others. Do not change your treatment yourself, but do not hide symptoms either, because early changes can help limit lasting damage.

Caring for hands and feet

With tablet chemotherapy, moisturise hands and feet often, avoid hot water, tight shoes and friction, and rest your feet when possible. Report redness, pain or peeling early. Your team may advise creams or a break from tablets, and they will decide whether any change to the plan is needed.

A blood test before starting

A small number of people have an inherited change that makes certain bowel cancer medicines much harder for the body to clear, leading to severe side effects. A blood test may be offered before treatment begins. Ask your team whether this test is recommended and available for you.

Living with a home pump

Some schedules use a small pump carried in a pouch for a day or two. Keep it dry, avoid pulling the tubing, sleep with it secured and follow the spill instructions you are given. You return to the unit, or a nurse visits, to disconnect it safely.

Chemotherapy with a stoma

Loose motions can increase stoma output quickly and lead to dehydration. Watch for thirst, dizziness and dark urine, and drink plenty of fluids. Your stoma nurse can advise on bags, skin care and diet, and your team should know if output rises sharply or you feel faint when standing up.

When cancer has spread to the liver

For some people, spots of bowel cancer in the liver can be removed with surgery, sometimes after chemotherapy shrinks them. A specialist liver surgeon should review scans before this option is ruled out. Your oncologist can arrange a joint review if it has not yet happened.

Gene tests for advanced cancer

For bowel cancer that has spread, the tumour is tested for gene changes that decide whether certain targeted medicines can be added to chemotherapy. Ask whether these tests have been done, because the results can change which combination is recommended and how the plan is structured.

Costs and planning

Cost depends on the schedule, the number of cycles, home pumps, tablets, targeted medicines and scans. Targeted medicines add significantly to cost. Ask for a written estimate covering the whole course, and ask about insurance and government schemes that may help your family through the months of treatment.

What to do next

Get your tissue sample report, ask how long your course will be and whether it comes before or after surgery, learn the cold precautions, and report tingling or sore hands early.