Cancer operation after chemo-radiotherapy: When should it be done?20 Jan 2016
Researchers analyzing data from the National Cancer Data Base (NCDB) have found that patients who had a cancer operation at precisely eight weeks--56 days--after the end of combined chemo-radiotherapy had the best overall survival and successful removal of their residual tumors.
The six-year study of almost 12,000 patients may bring clarity to doctors who have long debated the ideal waiting time between combined chemotherapy and radiation for rectal cancer and surgical removal of the cancer.
Patients with many types of cancer typically have a course of combined chemotherapy and radiation treatments before undergoing surgery to remove the tumors. The treatment before the operation helps to treat surrounding tissue and shrink the tumor.
One of the largest studies of its kind
The study investigated outcomes of 11,760 patients with advanced stage localized rectal cancer who had chemo-radiotherapy and surgical treatment from 2006 to 2012. The patients had either stage 2 or 3 localized rectal cancer (stage 4 is the most advanced stage).
Lead study author, Christopher Mantyh, MD, FACS, of Duke University, noted that this study differs from previous studies that evaluated the interval between chemo-radiotherapy and surgery for rectal cancer in its sheer size; previous studies were typically smaller and involved single institutions.
"Due to its size, we thought that the National Cancer Data Base was a perfect resource to answer the question about the timing of surgery after chemo-radiotherapy for rectal cancer. The data-set represented all types of hospitals," Dr Mantyh said.
Key-measures of cancer research treatment
The researchers set out to determine the best timing interval in terms of two key measures of success in cancer treatment:
- Margin positivity, that is, the cancer-free zone in the tissue surrounding the cancerous tumor after it is surgically removed; and
- Tumor down staging, which means the amount of the tumor that is downgraded in terms of its size and penetration into surrounding tissue.
Secondary outcomes the study evaluated were readmission and death rates within 30 days of hospital discharge and overall survival.
The study analysis divided patients into two groups: short-interval, those who underwent operations within 55 days of chemo-radiotherapy; and long-interval, having had an operation 56 days or more after radiotherapy.
The long-interval group was slightly older (age 59 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 3 disease (51.4% vs. 54.2%).
“Longer waiting times may risk tumor regrowth”
The investigators found that the median time between chemo-radiotherapy and surgery was 53 days, with the actual timing ranging from 43 to 63 days. "The odd thing about the study is that when we looked at the best timing for pathological down staging as well as margin positivity, they both arrived at exactly the same time--56 days," Dr Mantyh said.
Moreover, extending the delay beyond 56 days between radiation and surgery did not result in a greater down staging effect, but was associated with a higher likelihood of positive resection margins and compromised long-term survival, suggesting that longer waiting times may risk tumor regrowth.
Long-interval patients also had a lower risk of returning to the hospital within 30 days after surgery with no difference in death rates in that period, but they also had worse long-term survival. "The real significant thing we found was that long-term mortality was significantly higher after 56 days," Dr Mantyh reported.
The study findings can bring some clarity to the debate among oncologists about the timing of an operation after patients complete radiotherapy.Source: eCancer News