Comparison of toxicity experienced by older versus younger patients enrolled in breast cancer clinical trials

Abstract

Background: Elderly patients form a large proportion of patients with breast cancer but are underrepresented in clinical trials. We examined whether elderly patients experience more toxicity than younger patients within breast cancer clinical trials.

Materials and methods: All breast cancer trials open from 1999 to 2012 at BCCA, Vancouver Center, were reviewed. The primary endpoint was meaningful toxicity (MTOX), defined as any grade 3 or 4 adverse event (AE), any AE leading to dose delay or reduction, or premature discontinuation of therapy.

Results: In the 46 trials enrolling 799 patients, the therapy given was chemotherapy to 18% of the patients, hormonal therapy to 40%, skeletal therapy to 14%, and targeted therapy and a combination of chemotherapy and targeted therapy to 14%. Elderly patients were more likely to enroll in hormonal and skeletal therapy trials, and younger patients were evenly distributed among the therapy types. Toxicity data were available for 778 patients (97%). Elderly patients and younger patients experienced a similar number and frequency of MTOX. The therapy type was the strongest predictor of toxicity on multivariate analysis. In non-chemotherapy-containing trials, elderly and younger patients had a similar frequency and number of toxicities. Few elderly patients were enrolled in cytotoxic chemotherapy trials, but they experienced no more toxicity than did the younger patients.

Conclusion: The appropriate selection of elderly patients using eligibility criteria, self selection, and/or clinician assessment will allow safe participation of elderly patients in breast cancer trials.

Keywords: Chemotherapy; Elderly; Geriatric; Side effects; Toxicity.