Rectal cancer patients who underwent radiation therapy prior to total mesorectal excision surgery experienced half the recurrence rate of patients undergoing the same surgery without radiotherapy, according to a study being presented Nov. 1 at the annual meeting of the American Society for Radiation Oncology (ASTRO) in San Diego.
Previous studies have shown radiotherapy to be an effective pre-surgical treatment for reducing local recurrence in conventional rectal cancer surgery, but no study has examined the effects of radiation treatment on patients undergoing total mesorectal excision (TME), in which the entire mesorectum and lymph nodes are removed from the end of the patient's large intestine.
The study, conducted by Corrie Marijnen, MD, of Leiden University Medical Center in the Netherlands, and colleagues, included 1,861 patients with rectal cancer who were eligible for TME. Patients were randomly chosen to undergo either one week of 5 x 5 Gy radiotherapy and TME or TME alone. Median follow-up time was 11 years.
The researchers found that 6.4 percent of patients who underwent radiotherapy as well as TME experienced local recurrences during follow-up, while 13.3 percent of patients without radiation had local recurrences. Overall recurrence of rectal cancer (local or non-local) was also significantly lower for the radiotherapy group (28.8 percent) compared with the TME-only group (33.6 percent). No significant difference in overall survival was observed.
In sub-group analysis, the authors found that radiotherapy was only effective in reducing recurrences in patients when tumors were located more than 1 mm from the circumferential resection margins (negative CMR), in patients with TNM stage III and when tumor heights were above 5 cm.
"We believe that this short course of radiation will open a new window of opportunities in the treatment of rectal cancer," Marijnen concluded.