Chemotherapy courses after surgery could be cut in half for some colon cancer patients, according to a new global study.

Patients with colon cancer that has spread to the lymph nodes (stage 3) usually get 6 months of chemotherapy after surgery.

But researchers found that shortening treatment to 3 months did not affect the chance of cancer returning for many patients. The shorter treatment time also significantly reduced side effects.

Reducing side effects

Chemotherapy after surgery can help stop colon cancer returning, but it “comes at a price,” said Professor Matthew Seymour, a Cancer Research UK-funded gastrointestinal cancer expert. “It’s a tough treatment to go through and leaves a significant number of patients with nerve damage,” he added. This damage can cause persistent pain, numbness, or tingling in people’s fingers and toes.

“Thanks to this research, we can now confidently offer patients a shorter course of chemotherapy, which will greatly reduce the side effects of the treatment,” said Seymour.

The study involved 12,834 patients in 12 countries and was published in the New England Journal of Medicine.

“This study has shown that when there’s a really important question that matters to patients it’s possible to get clinicians from around the world to come together and answer it,” said Seymour. “It’s a huge achievement.”

Personalizing treatment

Patients in the trial had either 3 or 6 months of chemotherapy after surgery to remove their cancer.

Researchers found that while a 3-month course worked for many patients, those who were deemed at a higher risk of their cancer coming back benefited more from the standard, 6-month course. The risk of the disease returning was assessed by examining how deep the tumor was in the colon wall and how many lymph nodes the cancer had spread to.

Dr. Jeffery Mayerhardt, from Harvard Medical School in the US and who was involved in the study, said the results show there isn’t a “one size fits all answer” for chemotherapy after surgery. “Personalization based on the cancer characterization and treatment choice is important,” he added.