Survival estimates are critical factors in physician and patient decision making in all phases of a serious and/or life-threatening illness. However, prognostic estimates in patients with advanced terminal cancer may have increased importance as they approach the end of life, since this is a natural time to formally reevaluate the goals of treatment, with palliative care becoming more prominent, and disease-directed therapy less so.
However, despite its importance, prognostication in advanced terminal cancer is imperfect. Physicians are typically optimistic in their estimates of patient survival, and the prognostic estimates they communicate to patients may be even more optimistic. In an effort to improve these estimates, investigators are integrating previously established prognostic factors into easy to use models that physicians can use in the clinical care of their patients with advanced terminal cancer. The goal of improved prognostication is to provide patients with a better understanding of their expected survival and thereby allow them to make informed medical and social choices regarding their treatment path at the end of life, whether disease-directed, palliative, or a combination of both [1,2].
Here we discuss general aspects of estimating survival in patients with advanced terminal cancer. Prognostic estimates and the factors that influence outcome in specific cancers are discussed in separate topic reviews that cover individual tumors.
ACCURACY OF SURVIVAL ESTIMATES
Survival estimates that physicians make, guided only by their intuition and clinical experience, are called formulated prognoses. In the clinical setting of advanced terminal cancer, these formulated estimates are usually incorrect and the direction of the error is almost always optimistic [3-10]. That is, physicians tend to believe their patients have longer to live than they actually do. The disparity in actual versus estimated survival varies in different studies (table 1) [3-7,11-17]. In an illustrative study, 343 physicians referring 468 patients to one of five Chicago-area hospices were asked to provide an estimate of their patient's prognosis ("What is your best estimate of how long this patient has to live?), and they compared these prognostic estimates with actual survival . The median observed patient survival was 24 days, and the mean ratio of predicted to observed survival was 5.3.
Nevertheless, formulated prognoses are of value, particularly when integrated with other methods to estimate the length of remaining life [5,6,18,19]. As an example, in one study, multivariate regression models that included physicians' prognostic estimates were more accurate than models without physician input . Thus, while it is true that statistical models can be more accurate than human intuition alone [20-22], it is also true that physicians provide important information that is not captured in the models alone.