Completing Chemotherapy for Colorectal Cancer: Benefits and Challenges
For patients with stage III colorectal cancer, two recent studies confirm the benefit of completing adjuvant chemotherapy, but also highlight some of the difficulties. Both studies focused on individuals over the age of 65.
Colorectal cancer is the second leading cause of cancer-related deaths in the U.S. Stage III colon cancer refers to cancer that has spread from the colon to nearby sites, but not to distant sites in the body. Standard treatment for stage III colon cancer includes the surgical removal of cancer if possible and chemotherapy with or without radiation therapy.
To evaluate the extent to which older patients with stage III colorectal cancer are able to complete chemotherapy, two recent studies evaluated information from a dataset that links Medicare data to a large U.S. cancer registry.
The first study evaluated patients who were diagnosed with stage III colorectal cancer between 1992 and 1996.  Among patients who started chemotherapy following their colorectal cancer diagnosis, 78% of patients completed chemotherapy. As expected, patients who completed chemotherapy had a lower risk of cancer-related death than patients who did not complete chemotherapy.
One of the goals of the study was to determine which patients are at greatest risk of not completing chemotherapy. The researchers found that patients were less likely to complete adjuvant chemotherapy if they were female, widowed, over the age of 75, or required readmission to the hospital in the weeks or months following surgery.
The researchers conclude that frailty, treatment complications, and lack of social support are factors that may contribute to incomplete adjuvant treatment of patients with stage III colon cancer. The researchers note that development of interventions to improve social and physical support throughout treatment may increase treatment completion.
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The second study evaluated patients who were diagnosed with stage III colorectal cancer between 1995 and 1999. Factors that were linked with a decreased likelihood of completing chemotherapy were older age, being unmarried, and having other serious health problems.
As in the previous study, completion of chemotherapy was linked with a lower risk of death. Among patients who survived for at least eight months, risk of death was 40% lower in patients who received five to seven months of chemotherapy compared to patients who received one to four months of chemotherapy.
These studies provide additional evidence that completing the recommended course of chemotherapy improves survival among older patients with stage III colorectal cancer, but also point out that certain subgroups of patients are less able to complete treatment. Efforts to overcome barriers to chemotherapy completion may improve survival among patients at risk of stopping chemotherapy early.
Dobie SA, Baldwin L-M, Dominitz JA et al. Completion of Therapy by Medicare Patients with Stage III Colon Cancer. Journal of the National Cancer Institute. 2006;98:610-19.
 Neugut A, Matasar M, Wang X, et al. Duration of Adjuvant Chemotherapy for Colon Cancer and Survival Among the Elderly. Journal of Clinical Oncology. Early on-line publication April 17, 2006. DOI: 10.1200/JCO.2005.04.5005.