Estimating survival time in older adults receiving chemotherapy for advanced cancer.

Abstract

e23017 Background: Best-case, worst-case, and typical scenarios for survival time, based on an oncologist’s estimate of expected survival time (EST), have proven accurate in a range of advanced cancers. We sought the accuracy and prognostic significance of such estimates, and of a simple, pragmatic rating of frailty, in older adults starting chemotherapy. Methods: Participants (pts) were aged 65 or older and starting a new line of chemotherapy for advanced cancer. For each pt at baseline, their treating oncologist recorded an individualised estimate of EST (median survival in a group of similar patients), ECOG performance status (PS), and rating of frailty with the single-item, Clinical Frailty Scale from the Canadian Study of Health and Aging. We hypothesised that estimates of EST would be unbiased (approximately 50% of pts would live longer than their EST); imprecise ( < 33% would live for 0.67 to 1.33 times their EST); and, that simple multiples of the EST would provide accurate individualised scenarios for survival time, i.e. approximately 10% of pts would die within ¼ of their EST, 10% would live longer than 3 times their EST, and 50% would live from half to double their EST. We identified independent predictors of observed survival time (OST) with multivariable Cox regression. Results: Baseline characteristics of the 102 pts were: median age 74 (range 65-86), 1st line chemotherapy in 67%, colorectal cancer in 33%, PS 0 or 1 in 80%, and frailty rating of vulnerable to frail in 35%. The median EST was 15 months (range 4-60), median follow-up time was 19 months (range 0-27), and median OST was 15 months (range 0.5-27+). As hypothesized, 54% of pts lived longer than their EST, 30% lived within 0.67 to 1.33 times their EST, 56% lived half to double their EST, and 9% lived ≤1/4 of their EST. Follow-up was too short to observe those who will live ≥3 times their EST. Independent predictors of OST were frailty (HR 2.8, 95%CI 1.6-4.9, p = 0.0004) and EST (HR 0.96, 95%CI 0.93-0.99, p = 0.03). Conclusions: Oncologists’ estimates of EST were unbiased, imprecise, and accurate for formulating scenarios for survival time. A simple, pragmatic rating of frailty by the treating oncologist was a strong predictor of OST even after accounting for their estimate of EST.