Overall survival was best and resection of residual locally advanced rectal tumors most successful when surgery occurred at precisely 8 weeks, or 56 days, after completion of chemoradiotherapy. This analysis of data from the National Cancer Data Base (NCDB) was a 6-year study including almost 12 000 patients, published in the Journal of the American College of Surgeons (doi:10.1016/j.jamcollsurg.2015.12.017).

The study may bring clarity to the long debate about the ideal waiting time between combination chemotherapy/radiation treatment for rectal cancer and surgical resection of the cancer.

The Centers for Disease Control and Prevention (CDC) estimate 135 000 new cancer cases and 51 000 deaths per year are due to colon and rectal cancers. This makes colon and rectal cancers the third most common cancers in the United States. (CDC data does not separate out colon and rectal cancers.)

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The size of the study population is a key component of this study, as previous studies were typically smaller and involved single institutions.

“Due to its size, we thought NCDB was a perfect resource to answer the question about the timing of surgery after chemoradiotherapy for rectal cancer. The data set represented all types of hospitals,” said study leader Christopher R. Mantyh, MD, FACS, of the Duke University Department of Surgery in Durham, North Carolina. NCDB captures an estimated 70% of newly diagnosed cancer cases in the United States.

The median time between chemoradiotherapy and surgery was found to be 53 days, with actual time ranging from 43 to 63 days.

Patients were divided into 2 groups: short-interval (operations performed within 55 days of chemoradiotherapy) and long-interval (operation performed 56 days or more after radiotherapy). In the analysis, the long-interval group was slightly older (59 years vs 58 years), more likely to be black (9.5% vs. 8%), treated at an academic hospital, and less likely to have private insurance (50.2% vs. 55.4%) and stage III disease (51.4% vs. 54.2%).

A delay extended beyond 56 days was associated with a higher likelihood of positive resection margins and compromised long-term survival. This suggests longer waiting times are associated with risk of tumor regrowth. In addition, patients in the long-interval group had a lower risk of returning to the hospital within 30 days after surgery with no difference in death rates in that period; however, but long-term survival was worse.