Adjuvant Chemotherapy May Offer Survival Benefit in Older Patients With Colon Cancer

Patients 75 years of age or older with stage III colon cancer may expect a survival benefit from adjuvant chemotherapy that rivals that previously reported in younger patients, according to a recent study.

“From the perspective of a practicing clinician, these results suggest that consideration of adjuvant systemic therapy is absolutely warranted for patients older than 75,” Hanna K. Sanoff, MD, assistant professor in the Division of Hematology and Oncology at the Lineberger Comprehensive Cancer Center in Chapel Hill, North Carolina, and her co-authors wrote.

The researchers evaluated the effectiveness of any adjuvant chemotherapy for patients aged ≥75 years with stage III colon cancer using information from four data sets: the SEER cancer registry linked to Medicare claims (SEER-Medicare), the New York State Cancer Registry linked to Medicare claims, the NCCN Outcomes Database, and the Cancer Care Outcomes Research & Surveillance Consortium.

Overall, 5489 patients with resected stage III colon cancer who were diagnosed between 2004 and 2007 were included in the analysis.

While individuals aged ≥75 years account for 40% of the colorectal cancer population in the United States and about 50% of colorectal cancer deaths, they are underrepresented in clinical studies of colorectal cancer chemotherapy, Sanoff et al noted. As a result, there are limited efficacy data for this group of patients, which means that their oncologists have no “clear standards to guide treatment decisions.”

The present study, which was undertaken to examine actual practice patterns and outcomes, found that the use of adjuvant therapy was inversely associated with increasing age and greater comorbidity.

Chemotherapy receipt was associated with a survival benefit across the four cohorts. The significant 40% reduction in mortality risk associated with chemotherapy use in the SEER-Medicare cohort (hazard ratio = 0.60; 95% CI, 0.53-0.68) is comparable to the survival benefit found in clinical trials.

Sanoff et al also examined whether the addition of oxaliplatin provided an additional survival benefit. Oxaliplatin has been shown to increase cure rates for resectable stage III cancer in clinical trials, but very few patients in the pivotal trials were aged ≥75 years, which means that the benefit shown in those studies had not been documented in the older population.

The researchers’ analysis found, however, that oxaliplatin offered no more than a small incremental benefit.

The authors emphasized that their study was not able to measure quality of life. Thus, the effect of adjuvant therapy on quality of life in older patients with cancer remains an important unknown.

Sanoff HK, Carpenter WR, Stürmer T, et al. Effect of adjuvant chemotherapy on survival of patients with stage III colon cancer diagnosed after age 75 years. J Clin Oncol. 2012;30(21):2624-2634.