June 25, 2007 — Postoperative adjuvant chemotherapy for patients with stage 2 colon cancer remains controversial, but it can be considered in patients with poor prognostic features. According to the results of a study presented at the annual meeting of the American Society of Colon and Rectal Surgeons, the presence of certain high-risk factors can significantly affect disease-specific survival, and postoperative chemotherapy should be considered in these patients.
Although the overall prognosis after a curative resection is generally excellent, about 20% of patients with respectable stage 2 colon cancer will experience a recurrence and die from the disease, explained senior author Martin Weiser, MD, a surgical oncologist at Memorial Sloan-Kettering Cancer Center (MSKCC), New York, New York. "Our study was designed to identify that 20% so that we could potentially treat them."
The prognosis for patients with stage 3 disease is less favorable, with a 50% to 60% chance of developing recurrent disease after a complete surgical resection. Data from clinical trials found that postoperative chemotherapy could reduce the risk for mortality by approximately 30% (relative risk reduction), which translates to a greater than 10% absolute improvement in 5-year survival (J Clin Oncol. 2004;22:3408-19). Since a benefit was derived for patients with stage 3 disease, it was believed that a similar benefit might be possible for those with stage 2 colon cancer.
Data from both randomized controlled trials and meta-analyses of randomized controlled trials, however, have not identified a survival benefit for patients with stage 2 colon cancer who received adjuvant chemotherapy. Guidelines from the American Society of Clinical Oncology do not recommend the routine use of adjuvant chemotherapy in this population, although a large number of patients with stage 2 disease do receive postoperative adjuvant chemotherapy, despite the fact that evidence for a survival benefit is lacking (J Clin Oncol. 2004;22:3408-19). Data from the Surveillance, Epidemiology, and End Results-Medicare linked database showed that more than a quarter of patients with resected stage 2 colon cancer and no adverse prognostic features received chemotherapy during the first 3 months following their surgery (J Clin Oncol. 2002:3999-4005).
"The purpose of our study was to identify high-risk factors in patients with stage 2 disease," Dr. Weiser told Medscape. "This was a retrospective study, so we had data on early recurrence and death from cancer. If we can identify who is at risk for recurrence, then we can target them for chemotherapy.
Dr. Weiser and colleagues reviewed a database at MSKCC and identified 443 patients with stage 2 colon cancer who were treated with curative resection alone between 1990 and 2001. The patients were followed for a median of 53 months, and the 5-year disease-specific survival was 90%.
The researchers were able to identify 3 high-risk factors that were associated with a poor outcome. These were tumor stage T4, a preoperative carcinoembryonic antigen above 5.0 ng/mL, and the presence of lymphovascular or perineural invasion.
Dr. Weiser pointed out that survival appeared to be significantly influenced by the presence of a number of prognostic factors. "We found that patients without any of these 3 risk factors had a 5-year survival rate that was greater than 95%. But patients with 2 or more risk factors had a 5-year survival of less than 60%."
"These factors can be used by clinicians to identify patients who should receive postoperative chemotherapy," said Dr. Weiser. "These clinical pathological factors can identify patients with stage 2 disease who are at the highest risk of recurrence, and who might benefit from adjuvant therapy."
American Society of Colon and Rectal Surgeons: Abstract S11. Presented on Monday June 4, 2007.
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