Outcomes when cancer treatment is delivered on, or off, a clinical trial: implications for generalizability of study results

Contraindicated use of bevacizumab and toxicity in elderly patients with cancer

PURPOSE

Drugs are approved on the basis of randomized trials conducted in selected populations. However, once approved, these treatments are usually expanded to patients ineligible for the trial.

PATIENTS AND METHODS

We used the SEER-Medicare database to identify subjects older than 65 years with metastatic breast, lung, and colon cancer, diagnosed between 2004 and 2007 and undergoing follow-up to 2009, who received bevacizumab. We defined a contraindication as having at least two billing claims before bevacizumab for thrombosis, cardiac disease, stroke, hemorrhage, hemoptysis, or GI perforation. We defined toxicity as first development of one of these conditions after therapy.

RESULTS

Among 16,085 metastatic patients identified, 3,039 (18.9%) received bevacizumab. Receipt of bevacizumab was associated with white race, later year of diagnosis, tumor type, and decreased comorbid conditions. Of patients who received bevacizumab, 1,082 (35.5%) had a contraindication. In multivariate analysis, receipt of bevacizumab with a contraindication was associated with black race (odds ratio [OR] = 2.6; 95% CI, 1.4 to 4.9), increased age, comorbidity, later year of diagnosis, and lower socioeconomic status. Patients with lung (OR = 1.7; 95% CI, 1.1 to 2.4) and colon cancer (OR = 1.4; 95% CI, 1.1 to 1.9) were more likely to have a contraindication. In the group with no contraindication, 30% had a complication after bevacizumab; black patients were more likely to have a complication than were white patients (OR = 1.9; 95% CI, 1.21 to 2.93).

CONCLUSION

Our study demonstrates widespread use of bevacizumab among patients who had contraindications. Black patients were less likely to receive the drug, but those who did were more likely to have a contraindication. Efforts to understand toxicity and efficacy in populations excluded from clinical trials are needed.