Survival Associated with 5-Fluorouracil–Based Adjuvant Chemotherapy among Elderly Patients with Node-Positive Colon Cancer

Survival Associated with 5-Fluorouracil–Based Adjuvant Chemotherapy among Elderly Patients with Node-Positive Colon Cancer

From Joseph L. Mailman School of Public Health, the Herbert Irving Comprehensive Cancer Center, and College of Physicians and Surgeons, Columbia University, New York, New York.

Abstract

Background: Randomized clinical trials have demonstrated the efficacy of adjuvant 5-fluorouracil (5-FU)-based chemotherapy after surgical resection of node-positive colon cancer. Although this treatment became the standard in 1990 following a National Institutes of Health Consensus Conference, among those at least 65 years of age it is less likely to be offered to older or nonwhite patients.

Objective: To determine the association between 5-fu–based chemotherapy and survival in older patients.

Design: Retrospective cohort study.

Setting: Combined database of the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program and Medicare.

Patients: 4768 patients 65 years of age or older who received a diagnosis of node-positive colon cancer from 1992 to 1996, were covered by Medicare Parts A and B, and resided in the population covered by the SEER program.

Measurements: Propensity scores to control for known predictors of receiving treatment, Cox proportional-hazards models to assess the association of 5-FU therapy with survival, and sensitivity analyses to estimate the possible effects of unknown confounders.

Results: Fifty-two percent of patients received 5-FU therapy. For this sample, the hazard ratio for death associated with 5-FU therapy was 0.66 (95% CI, 0.60 to 0.73). Confounding could have accounted for this association only if an unmeasured confounder were extremely unequally distributed between the treated and untreated groups or increased mortality by at least 50%.

Conclusions: 5-Fluorouracil adjuvant therapy is significantly associated with reduced mortality in older patients, similar to the association found in randomized, controlled trials among younger patients. More frequent use of 5-FU therapy in older patients would probably reduce death from colon cancer.

Article and Author Information

Disclaimer: Although this study used the linked seer–medicare database, the interpretation and reporting of these data are solely the authors' responsibility.
Acknowledgments: The authors acknowledge the efforts of the Applied Research Branch, Division of Cancer Prevention and Population Science, National Cancer Institute; the Office of Information Services and the Office of Strategic Planning, Health Care Financing Administration; Information Management Services, Inc; and the SEER Program tumor registries in the creation of the seer–medicare database.
Grant Support: By a grant from the American Cancer Society (RSGHP-01-024-01-CCE). Dr. Grann is the recipient of an American Cancer Society Award (CRTG-98-260-01). Dr. Mitra was supported by a predoctoral fellowship from the National Cancer Institute (T32 CA09529). Dr. Neugut is the recipient of a K05 award from the National Cancer Institute (CA89155). Drs. Heitjan and Neugut were supported in part by NCI P30 CA13696.
Requests for Single Reprints: Alfred I. Neugut, MD, PhD, Division of Medical Oncology, New York Presbyterian Hospital, PH 18-127, 630 West 168th Street, New York, NY 10032; e-mail, ain1{at}columbia.edu.
Current Author Addresses: Dr. Sundararajan: Department of Epidemiology and Preventive Medicine, 553 Kilda Street, Alfred Hospital, Monash Medical School, Melbourne, Victoria 3181, Australia.
Drs. Mitra and Heitjan: Department of Biostatistics, Joseph L. Mailman School of Public Health, Columbia University, 600 West 168th Street, New York, NY 10032.
Dr. Jacobson: Department of Epidemiology, Joseph L. Mailman School of Public Health, Columbia University, 600 West 168th Street, New York, NY 10032.
Drs. Grann and Neugut: Division of Medical Oncology, Columbia University College of Physicians and Surgeons, 630 West 168th Street, New York, NY 10032.
Author Contributions: Conception and design: V. Sundararajan, J.S. Jacobson, V.R. Grann, A.I. Neugut.
Analysis and interpretation of the data: V. Sundararajan, N. Mitra, V.R. Grann, D.F. Heitjan, A.I. Neugut.
Drafting of the article: V. Sundararajan, N. Mitra, V.R. Grann, A.I. Neugut.
Critical revision of the article for important intellectual content: V. Sundararajan, N. Mitra, J.S. Jacobson, V.R. Grann, D.F. Heitjan, A.I. Neugut.
Final approval of the article: V. Sundararajan, N. Mitra, J.S. Jacobson, V.R. Grann, D.F. Heitjan, A.I. Neugut.
Provision of study materials or patients: A.I. Neugut.
Statistical expertise: N. Mitra, D.F. Heitjan.
Obtaining of funding: V. Sundararajan, A.I. Neugut.
Collection and assembly of data: V. Sundararajan.