Results from a large multi-institutional clinical trial reported in the New England Journal of Medicine provide confirmatory evidence that treatment with pre-operative radiation significantly decreases local cancer recurrences in patients with rectal cancer that has not spread to distant sites and should be considered the standard of care for this disease.
The rectum comprises approximately the last 10 inches of the colon, or large intestine. Patients with rectal cancer that has not spread to distant sites in the body may be cured through the complete surgical removal (resection) of their cancer. Recently, results from previous clinical trials have demonstrated that radiation prior to surgery decreases cancer recurrences compared to treatment with surgery alone in rectal cancer. A decrease in cancer recurrences often correlates to improved long-term survival.
The concept behind the use of pre-operative radiation is to shrink cancer and kill undetectable cancer cells that may exist directly outside the site of cancer origin. Current detection methods are not able to find or measure small amounts of cancer cells that exist, therefore increasing the chance that they may be left behind following surgery. These cancer cells are responsible for cancer recurrences. In theory, through shrinking the site of cancer and killing nearby cancer cells, more complete surgical removal of the cancer may be obtained, resulting in fewer recurrences and improving chances for a cure.
A recent, large multi-institutional clinical trial was recently conducted which directly compared treatment of pre-operative radiation plus surgery to surgery alone in over 1800 patients with rectal cancer that had not spread to distant sites. Surgery consisted of total mesorectal excision, which is the removal of the lymphatic and vascular tissue surrounding the portion of the rectum removed. Two years following treatment, there was no difference in survival between the two groups of patients. However, local cancer recurrences had occurred in only 2.4% of patients treated with radiation plus surgery compared to 8.2% of patients treated with surgery alone.
These results confirm previous studies, indicating that preoperative radiation reduces the risk of local cancer recurrences in patients with rectal cancer that has not spread to distant sites. Although survival rates were equal at two years following therapy, longer follow-up is needed to truly determine survival advantages. Patients with rectal cancer may wish to speak with their physician regarding the risks and benefits of preoperative radiation and total mesorectal excision for optimal treatment. (New England Journal of Medicine, Vol 345, No. 9, pp 638-646, 2001)
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