Patterns of Colorectal Cancer Care in the United States: 1990-2010

Abstract

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.

Figure 1.

Proportion of stage III colon cancer patients diagnosed between 1990 and 2010 who received adjuvant chemotherapy by comorbidity score and age at diagnosis (n = 1849). Proportions weighted by sampling fraction. Figure excludes patients who did not undergo cancer-directed surgery (n = 9) or with missing or unknown chemotherapy agents (n = 82). Comorbidity score (CS) greater than 2 not shown for ages <55 and ≥80 years because of small number of observations (n < 5).

Figure 2.

Proportion of stages II and III rectal cancer patients who received preoperative or postoperative radiation therapy by year of diagnosis (n = 3016). Proportions weighted by sampling fraction. Figure excludes patients who did not undergo cancer-directed surgery (n = 145), received intraoperative radiation (n = 1), received both preoperative and postoperative radiation (n = 15), and those in whom a radiation sequence could not be determined (n = 13). XRT = radiation therapy.