Background/Aims: Chemotherapy for advanced (stage III/IV) colon cancer has changed with new drugs and combination regimens. Treatment guidelines for advanced disease are broad thus allowing for treatment variation. We evaluated cases enrolled at 7 HMO Research Network sites through the Comparative Effectiveness in Genomic and Personalized Medicine for Colon Cancer (CERGEN) study to describe characteristics and patterns of chemotherapy treatment by geographic site and patient characteristics.
Methods: Metastatic colon cancer cases diagnosed between 1/1/04 and 12/31/09 were identified. Information on relevant patient characteristics including comorbidities, treatment, KRAS test status, and utilization of acute and palliative care was collected electronically. Chart review was conducted to supplement and/or verify the electronic data. Tumor specimens were obtained for KRAS testing on cases not tested as part of standard care. Analysis included descriptive statistics, incidence rates, and Cox proportional hazards regression models.
Results: A total of 1,220 advanced Colon cancer cases, 422 with Stage III disease prior to progression and 798 with Stage IV disease were enrolled. The proportion of patients who received chemotherapy varied by stage (87%; 256 of 294 with stage III disease and 68%; 630 of 926 with stage IV disease at time of treatment, adjusted p-value=0.0452), geographic site (range 51–83%; adjusted p-value 0.0003; age (rate decreased with increasing age, adjusted p-value < 0.0001), Charlson Score (range score 0, 76%; 147 of 196 to score 6+, 46%; 118 of 257; adjusted p-value < 0.0001), Medicare coverage (yes, 90%; 311 of 346 vs. no, 66%; 577 of 874; adjusted p-value < 0.0001), and positive family history of cancer (family history 82%; 460 of 561 vs. no family history 71%; 258 of 363; adjusted p-value <0.0456), but did not vary by BMI, patient gender, race, level of education, or household income. The median time to treatment varied by geographic site, stage, increasing age, race, Medicare coverage, college education, household income, and other therapy but did not vary by gender, BMI, Charlson Score, or positive family history.
Discussion: Chemotherapy use and median time to treatment in advanced colon cancer varied by disease stage, geographic site, and patient characteristics.