Background: Colorectal cancer (CRC) mortality has declined in the United States, in part because of advances in treatment. Few studies have evaluated the adoption of therapies and temporal changes in patterns of care.
Methods: Patients age 20 years and older diagnosed with stages II/III CRC were randomly sampled from the population-based Surveillance, Epidemiology, and End Results (SEER) program in 1990-1991, 1995, 2000, 2005, and 2010 (n = 7057). Therapy was obtained from medical records and physician verification. We described the receipt of chemotherapy and radiation therapy. Log-binomial regression was used to examine factors associated with therapy. All statistical tests were two-sided.
Results: Chemotherapy receipt among colon cancer patients increased from 1990 (stage II: 22.5%; stage III: 56.3%) to 2005 (stage II: 32.1%; stage III: 72.4%) and declined slightly in 2010 (stage II: 29.3%; stage III: 66.4%). Stage III colon cancer patients who were older (vs <55 years, 75-79 years: risk ratio [RR] 0.81, 95% confidence interval [CI] = 0.71 to 0.91; ≥80 years: RR = 0.37, 95% CI = 0.28 to 0.47) or had a comorbidity score of 2 or higher (vs 0, RR = 0.56, 95% CI = 0.35 to 0.87) received chemotherapy less often. Receipt of radiation therapy by rectal cancer patients increased across all years from 45.5% to 66.1%. Increasing age (vs <55 years, 75-79 years: RR = 0.59, 95% CI = 0.47 to 0.74; ≥80 years: RR = 0.33, 95% CI = 0.25 to 0.45) was associated with lower chemoradiation use among stage II/III rectal cancer patients.
Conclusion: Our findings demonstrate increased adoption of chemotherapy and radiation therapy for colon and rectal cancer patients and differences in therapy by age, comorbidity, and diagnosis year. Increased receipt of these therapies in the community may further reduce CRC mortality.
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