Trends in Prostate Cancer Incidence and Mortality in New Mexico are Consistent With an Increase in Effective Screening

The increasing occurrence of prostate cancer in the United States has led to recommendations for routine prostate cancer screening in men aged 50 years and older. Although present methods of prostate cancer screening have not been shown to reduce mortality, screening using digital rectal examination or prostate-specific antigen does detect tumors at earlier stages. To assess whether trends in incidence and mortality rates are consistent with an increase in effective screening in New Mexico, we examined prostate cancer incidence rates calculated from data collected by the New Mexico Tumor Registry for the years 1969-1991, and mortality rates calculated from data collected by the New Mexico Bureau of Vital Statistics for the years 1958-1991. Population-based measures of prostate cancer screening frequency in New Mexico are not available for the period of this study; however, the proportion of prostate cancers detected by screening, as documented by a review of records from a random sample of prostate cancer cases, increased fold, from 13% during the 1969-1972 period to 41% in the 1988-1991 period. During the period of study, age-adjusted incidence rates increased from 66.3 to 122.3/100,000 men. Stage migration from distant to earlier stages was apparent in the increase in the proportion of early stage cancers from 77.5 to 85.5%, and the decrease of distant stage cancers from 21.2 to 9.8%. Stage-specific incidence rates increased for local (87.3%) and regional stage cancers (283.0%), and decreased for distant stage cancers (16.0%). Average annual age-adjusted mortality rates for prostate cancer decreased from 23.0/100,000 in the 1978-1982 period to 21.6/100,000 (6.1%) in the 1988-1991 period. Mortality peaked at 26.8/100,000 in 1980 and decreased to 21.2/100,000 by 1991. The decrease in mortality rates is consistent with stage migration from distant to earlier stages of disease and may reflect an increase in effective prostate cancer screening.