Health maintenance includes secondary prevention through cancer screening. There are no established guidelines for cancer screening patients with end-stage renal disease (ESRD). Using an established method of estimating life expectancy, published literature on cancer screening, and information from databases on mortality and malignancy (US Renal Data System 1997 Annual Data Report and the SEER Cancer and Statistical Review, 1973-1994), a "real-time life expectancy calculator" was developed to guide the primary help provider in making informed decisions on the benefits of cancer screening in individual patients. Potential days of life saved by each screening method can be calculated using the difference in life expectancy per the DEALE (declining exponential approximation of life expectancy) method with and without cancer screening. Using two sets of assumptions (one to enhance any bias toward support for screening and one to limit this bias), a range of potential days of life saved with screening for breast and colon cancer can be calculated in individual patients with ESRD. In breast cancer, for example, a 50-year-old black woman with ESRD and multiple risk factors would have 41 to 291 potential days of life saved with screening. A 60-year-old white woman with ESRD and diabetes mellitus (DM) would have only 1 to 16 days of life saved. This life expectancy calculator can guide the primary health care provider in making clinical decisions concerning screening in the ESRD population. In addition to assisting in patient education, the calculator can be updated as new information becomes available regarding relative risk, treatment, and mortality.