Adjuvant chemotherapy for colon cancer offers no survival benefit after 10 years


In 1988, a team of researchers reported that, for patients with colon cancer, postoperative chemotherapy was associated with better 5-year disease-free and overall survival than surgery alone. However, this survival benefit disappeared after 10 years, according to an update of that same clinical trial that appears in the August 4 issue of the Journal of the National Cancer Institute.

In 1977, the National Surgical Adjuvant Breast and Bowel Project (NSABP) began a randomized clinical trial, NSABP protocol C-01, to evaluate the efficacy of adjuvant chemotherapy or postoperative immunotherapy after surgery compared with surgery alone in colon cancer patients. More than 1000 patients with Dukes' stage B and C colon cancer who had surgery for their cancer were given either no further treatment, chemotherapy, or immunotherapy. Patients who were given chemotherapy had better 5-year disease-free and overall survival compared with the surgery-only group, whereas patients who were given immunotherapy had only better 5-year overall survival. Neither the three-drug chemotherapy regimen nor the immunotherapy regimen is in common use any longer.

Roy E. Smith, M.D., of the NSABP in Pittsburgh, and colleagues evaluated the follow-up data collected after 10 years. They found that the disease-free and overall survival benefit for patients who received chemotherapy had disappeared after 10 years. The immunotherapy regimen had a beneficial effect on 10-year overall survival but not disease-free survival. This improvement was associated with fewer deaths from conditions other than colon cancer among the older patients in the trial.

It should be noted, however, that because the chemotherapy and immunotherapy used in this trial are no longer recommended for colon cancer, it is possible that the newer chemotherapy regimens would be better than surgery alone, the authors write.

In an editorial, Jean Grem, M.D., of the University of Nebraska Medical Center in Omaha, notes that neither of the regimens tested in this trial are currently in clinical use, so there is a need to find appropriate surrogate end points for colon cancer trials to expedite the clinical testing phase of potential new agents. She suggests the possibility of using 3-year disease-free survival as a surrogate end point for 5-year overall survival, noting that its advantages include "allowing more timely completion of trials, and more rapid implementation of new trials testing promising new therapies."

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Last reviewed: By John M. Grohol, Psy.D. on 21 Feb 2009
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