New models estimate survival time in advanced cancer
A number of variables can be used to estimate whether a person with advanced cancer who is no longer being treated for the disease will live for days, weeks, or months.
Patrick C. Stone of St. George's University of London, United Kingdom, and colleagues have identified 11 core clinical and laboratory variables that independently predicted both 2-week and 2-month survival in a study of 1,018 patients with locally advanced or metastatic cancer. The participants were no longer undergoing treatment and had been referred to palliative care services.
Using a combination of factors known to predict survival, the investigators created two prognostic scores—one for patients without blood results (PiPS-A), and one for patients with blood results (PiPS-B). These models were then applied to calculate whether patients were likely to survive for “days” (0 to 13 days), “weeks” (14 to 55 days), or “months” (more than 55 days). The model-based predictions were compared with clinician predictions and actual patient survival.
Absolute agreement between actual survival and PiPS predictions was 57.3%, with the models performing as well as, or better than, clinicians' estimates of survival. PiPS-B was significantly more accurate than an individual clinician's prediction, but neither scale was significantly more accurate than a multiprofessional estimate of survival.
“In a clinical context, we believe that PiPS estimates would usually be used to inform and augment clinicians' own subjective estimates (rather than to replace them),” wrote the researchers in their report for BMJ–British Medical Journal (www.bmj.com/content/343/bmj.d4920.full.pdf). “However, our study suggests that the PiPS-B estimate of survival could now act as the ‘benchmark' against which new prognostic tools are assessed.”
The independent predictors of survival were:
- pulse rate
- general health status
- mental test score
- performance status
- presence of anorexia
- presence of any site of metastatic disease
- presence of liver metastases
- C-reactive protein
- white blood count
- platelet count
In addition, four variables had prognostic significance for 2-week survival only (dyspnea, dysphagia, bone metastases, and alanine transaminase), and eight variables for 2-month survival only (primary breast cancer, male genital cancer, tiredness, loss of weight, lymphocyte count, neutrophil count, alkaline phosphatase, and albumin).