Patient-Perceived Overall Side Effect Bother at and After Cancer Treatment Discontinuation: An Analysis Using Commercial Cancer Trial Data

INTRODUCTION: There is widespread interest among patients, clinicians, regulators and other constituents in post-treatment patient-reported cancer data. Side effect bother is a patient-reported outcome (PRO) that can capture an important aspect of tolerability. In this study, we examined side effect bother at cancer treatment discontinuation and post-discontinuation in commercial cancer trials. We sought to understand completion rates, the extent of bother and its association with other PROs. MATERIALS AND METHODS: Data were evaluated from three trials in patients with solid tumours (renal cell carcinoma and breast cancer). Side effect bother was measured with the Functional Assessment of Chronic Illness Therapy (FACIT) GP5 item. Symptom items were drawn from FACIT and function items were drawn from the EQ-5D-3L. FACIT items, including the GP5, are on a 0-4 scale (higher = worse symptoms/bother), and were dichotomised as 0-1 ("low") vs 2-4 ("moderate"). EQ-5D-3L items were characterised as no problems (1) and some problems (2-3). Descriptive and correlation analyses were conducted separately for each trial. RESULTS: Among patients who received treatment, completion rates at discontinuation for most items were at least 70%, and 52% to 78% at follow up. More than 20% of patients had high side effect bother at and after discontinuation, and similar percentages were seen for symptom items and functioning problems. GP5 and most items were at least somewhat correlated (≥ 0.2 in nearly all evaluations). DISCUSSION AND CONCLUSIONS: Persistent side effect bother and symptomatic and functional detriments at and after discontinuation suggest capturing this information post-treatment can inform understanding of tolerability, particularly with improved PRO completion.