Risk factors for unplanned discontinuation of scheduled treatment in elderly patients with castration-resistant prostate cancer: results of the IBuTu study.

Purpose: To gain knowledge about the factors associated with discontinuation of scheduled treatment in elderly men with castration-resistant prostate cancer (CRPC).

Methods: Patients ≥ 70 years with CRPC starting a new line of treatment were included in a prospective cohort study. A geriatric assessment (CGA) was performed at baseline, including comorbidity, mobility, functional/mental/nutritional status, as well as depression. Furthermore, pain intensity, quality of life, ECOG-performance status, and physicians' and patients' perception of health were documented. Reasons for and factors associated with discontinuation of scheduled treatment were analysed by univariate and multivariate analysis.

Results: After inclusion of 177 of 300 planned patients, the study was closed due to slow recruitment. 160 patients were eligible for final analysis. Median age was 77.5 years. 46% received chemotherapy, and 54% hormonal treatment. Discontinuation of scheduled treatment occurred in 91 patients (57.6%). The main reasons were progressive disease/death in 63%, adverse events/toxicity in 22%, and withdrawal of consent in 8%. In bivariate analyses, factors associated with discontinuation of treatment were age ≥ 80 years, ECOG PS ≥ 2, compromised/poor health status (physicians'/patients' assessment), and compromised functional or nutritional status. In multivariate analysis, the only remaining factor independently associated with discontinuation of scheduled treatment was impairment of activities of daily living (ADL < 100 points) (OR = 4.2 for discontinuation; p < 0.05).

Conclusion: Despite limitations due to early termination of the study, our results demonstrate that discontinuation of scheduled treatment was common, and that compromised ADL seems to be a significant risk factor for treatment failure in elderly patients with CRPC.