Survival benefit of adjuvant chemotherapy for colon cancer limited
Last Updated: August 04, 2004



NEW YORK (Reuters Health) - In 1988 the results from the National
Surgical Adjuvant Breast and Bowel Project (NSABP) protocol C-01
showed that for patients with Duke's stage B and C colon cancer,
chemotherapy after surgery led to a statistically significant
increase in 5-year disease-free and overall survival than surgery
alone.


At 10 years, however, the survival benefit of adjuvant chemotherapy
had disappeared, the investigators now report in the August 4th
Journal of the National Cancer Institute.

The 10-year follow up data included 375 patients treated with surgery
alone, 349 treated postoperatively with MOF chemotherapy (MeCCNU or
semustine, plus vincristine, and 5-FU), and 372 treated with adjuvant
bacillus Calmette-Guerin (BCG) immunotherapy after resection.

According to Dr. Roy E. Smith of the NSABP in Pittsburgh and
colleagues, there were no differences in the chemotherapy and surgery-
alone group in 10-year disease-free or overall survival curves.

Nonetheless, chemotherapy probably did attenuate the course of colon
cancer, according to the team, noting that a statistically
significant disease-free survival benefit was evident "from as early
as 1 year after randomization for as long as 8 years of follow up."

"Although the mechanism responsible for this early disease-free
survival advantage remains speculative, analysis of relapse-free
survival indicates that there was an early delay in recurrence," they
add.

The investigators also point out that MOF chemotherapy is no longer a
recommended regimen for colon cancer based on subsequent trials of
more effective regimens. "Thus, it is possible that the newer
chemotherapy regimens would be better than surgery alone," they write.

BCG immunotherapy appeared to have a beneficial effect on overall but
not disease-free survival at 10 years, although this may be a "chance
finding because it was an unanticipated effect," the team notes.

In contrast to chemotherapy, immunotherapy does not appear to
favorably alter the natural course of the primary malignancy. Rather
the survival benefit appears to result from a reduction in deaths
associated with comorbid conditions in this elderly population.

Noting in an editorial that MOF is outdated, Dr. Jean Grem from the
University of Nebraska Medical Center in Omaha favors adopting 3-year
disease-free survival as a surrogate end point for 5-year overall
survival in adjuvant colon cancer trials. This would allow "more
timely completion of trials, and more rapid implementation of new
trials testing promising new therapies."





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