Optimal waiting time to surgery after radiation therapy in rectal cancer

This study investigated the appropriate waiting time to surgery after radiation and chemotherapy in rectal cancer patients.

Researchers suggested that 56 days is the optimal waiting time for surgery after completion of radiation or chemotherapy.

Chemotherapy and radiation prior to surgery to remove rectal cancer has been associated with increased tumor control. Prior studies have shown that a longer waiting time between radiation or chemotherapy and surgery is more beneficial. However, the optimal waiting time before surgery is not clear.

The objective of this study was to evaluate the optimal waiting time for surgery after radiation or chemotherapy. This study included information on 11,760 patients with stage 2 (47%) and stage 3 (53%) rectal cancer. All patients were listed in a national cancer database. All patients underwent chemotherapy or radiation therapy prior to surgery. The time between the last treatment and surgery was measured.

There was an increase in the odds of tumor shrinkage over 56 days after the end of treatment. After 56 days, there was no further benefit. Positive margins (cancer cells found in the outer edges of the removed tissue) were 40% more likely if surgery took place after 56 days.

This study determined 56 days (8 weeks) was the optimal time between radiation or chemotherapy and surgery.

This study did not determine why waiting up to 56 days between radiation and/or chemotherapy and surgery improves cancer regression.