Usefulness of medical oncologists’ estimates of survival time in people with advanced cancer.

Abstract

9087 Background: We sought to determine the calibration, precision, prognostic significance and suitability of estimated survival time (EST) as a basis for estimating and explaining prognosis in advanced cancer. Methods: Medical oncologists recorded their EST as the “median survival of a group of identical patients” in patients with advanced cancer and a life expectancy >3 months recruited to a randomized trial of sertraline (Lancet Oncol 2007; 8: 603). Calibration, precision and suitability were defined by the proportions of patients whose observed survival times (OST) were bounded by simple multiples of their EST (based on our previous studies), i.e. 50% expected to live longer (or shorter) than their EST; 30% expected to live from 0.75 to 1.33 times their EST (arbitrary criterion for precision); 50% expected to live from half to double their EST (range for typical scenario); 10% expected to live >3 times their EST (best case scenario), or <¼ of their EST (worst case scenario). Results: Characteristics of the 114 patients were: median age 63 years, Karnofsky performance status (KPS) ≤70 in 25%, and a median of 8.5 months since diagnosis of advanced cancer. Primary cancer sites included breast (18%), colorectal (16%), lung (15%), prostate (12%) and ovary (10%). Median survival was 10.6 months after a median follow-up of 14 months and 68 deaths. EST were well-calibrated: 54% of patients lived longer than their EST and 46% lived shorter than their EST. EST were imprecise (21% within 0.75 to 1.33 times OST) but equally likely to be over-optimistic (34% >1.33 x OST) or over-pessimistic (39% <0.75 x OST). 6% of patients lived <¼ of their EST; 62% lived from half to double their EST and 9% lived >3 times their EST. Independently significant predictors of OST in a multivariable Cox model included EST (HR=0.92, p=0.004), dry mouth (HR=5.07, p<0.0001), alkaline phosphatase >101U/L (HR=2.80, p=0.0002), KPS ≤70 (HR=2.30, p=0.007), prostate primary (HR=0.23, p=0.002), and steroid use (HR=2.35, p=0.02). Conclusions: Medicaloncologists’ EST were well-calibrated, imprecise, independently associated with OST, and useful for estimating and explaining best case, worse case, and typical scenarios for survival time in patients with advanced cancer.