The results of a randomised, phase III trial, presented at the American Society of Clinical Oncology (ASCO), have found that adding bevacizumab (Avastin) to standard adjuvant chemotherapy did not improve disease-free survival (the time that patients are free of tumour recurrence) in early stage colon cancer.

This was the first study to report results on the use of bevacizumab as an adjuvant treatment. The antibody, which targets the vascular endothelial growth factor (VEGF) receptor, is currently approved for metastatic colorectal, breast, and lung cancers, and other trials are ongoing to evaluate it as an adjuvant treatment for a variety of solid tumours.

The current study enrolled 2,710 patients who were randomised to receive six months of standard adjuvant chemotherapy or six months of adjuvant chemotherapy combined with bevacizumab plus an additional six months of bevacizumab after the chemotherapy had ended. All patients in the study had stage II or stage III disease and first had surgery to remove their tumors. After a median follow-up of three years, the investigators found that 77.4 per cent of patients in the experimental group (bevacizumab) were alive and free of disease, compared with 75.5 per cent of patients in the control group, a difference that was not statistically significant. There were no unexpected side effects in either arm and the toxicities from bevacizumab were well tolerated.

"One interesting effect was that during the year that patients were receiving bevacizumab we saw a benefit in disease-free survival that subsequently diminished when follow-up was completed," said Dr. Norman Wolmark, chairman of the Department of Human Oncology at Allegheny General Hospital and the study’s lead author. "Our overall conclusion is that bevacizumab was not effective as an adjuvant treatment for early-stage colon cancer, but the transient benefit we saw in patients who received bevacizumab illustrates that we have more to learn about how this reagent works, and we need to design more clinical trials to determine how it can be used most effectively."

The trial was conducted by the National Surgical Adjuvant Breast and Bowel Project (NSABP) group, chaired by Dr. Wolmark, and was funded by the National Cancer Institute.