3-month versus 6-month adjuvant chemotherapy for patients with high-risk stage II and III colorectal cancer: 3-year follow-up of the SCOT non-inferiority RCT.

Patients diagnosed with bowel cancer are likely to have surgery to remove the tumour. Patients diagnosed with a more advanced stage of the disease are then likely to be offered what is known as adjuvant chemotherapy ­ chemotherapy to kill any cancer cells that have already spread but cannot be seen. Adjuvant chemotherapy is usually given over 6 months using two medicines known as oxaliplatin and fluoropyrimidine. This chemotherapy has side effects of diarrhoea, nausea and vomiting, and it reduces the numbers of cells in the blood. It can also damage nerves, which causes discomfort, numbness and tingling; in some cases, this can go on for years. These side effects are more likely to develop with longer treatment. This study looked at whether or not shortening the time over which patients were given oxaliplatin and fluoropyrimidine chemotherapy reduced its effectiveness. In this large study of over 6000 patients, half of the patients were allocated by chance to be treated for 3 months and the other half to be treated for 6 months. Reducing the time that patients had chemotherapy from 6 months to 3 months did not make the treatment less effective. When patients treated with chemotherapy over 3 months were compared with those treated over 6 months, 77% of patients in both groups were well with no detectable disease 3 years after surgery. Patients were less likely to get side effects with 3-month chemotherapy. In particular, the chance of persistent long-term nerve damage was lower, resulting in patients with 3-month chemotherapy having better health-related quality of life. Overall, the study showed that 3-month adjuvant chemotherapy for patients with bowel cancer is as effective as 6-month adjuvant chemotherapy and causes fewer side effects.