Fraction of normal remaining life span: a new method for expressing survival in cancer.

Conventionally, the time between diagnosis and date of last follow up or death is used to plot survival curves for patients with cancer. This ignores the patient's expected life span had the patient been healthy at the time of diagnosis. In human terms the impact of a projected prognosis of 10 year survival on a woman diagnosed as having breast cancer, for example, may be different depending on whether she is aged 30 or 70. Furthermore, oncologists have no answer to the question: "What is my chance of cure?" For this reason, we believe that survival is better expressed as a fraction of normal remaining life span expected at the time of diagnosis. We propose a new method which takes account of age at diagnosis in calculating survival.