[Prostate cancer screening (III): risk factors, natural history, course without treatment. Characteristics of detected cancers].

The Oncology Committee of the Association Française d'Urologie has up-dated the knowledge concerning prostatic cancer screening since the 1989 Consensus Conference. The results are published in the form of a series of articles referring to the criteria used as prerequisites for cancer screening programmes. This article reports the data of the literature concerning risk factors, natural history, course without treatment and histological characteristics of the cancer detected. 1) Certain populations have an increased risk due to genetic factors. A family history (first degree relative) is associated with a 2- to 3-fold higher risk of prostatic cancer. This familial aggregation can be used to define a high-risk group constituting a primary target for screening. 2) The natural history of the disease, especially the progression from the asymptomatic stage to the clinical stage and the natural history of the disease at the clinical stage are now sufficiently well known. The concept of latent cancer has not been confirmed as the disease inevitably progresses. Cancers of insignificant volume, less than 0.5 cc (discovered at autopsy) are classically distinguished from cancers of significant volume, greater than 0.5 cc, but asymptomatic (risk of progression with mortality within 15 years), and local and/or metastatic symptomatic cancers. The histological prevalence of prostatic cancer is 43% in a group of men with a mean age of 64 years and increases with age. 92% of histological cancers have a volume less than 0.5 cc. It takes an estimated 12 years (3 doubling times) for a 0.5 cc cancer to reach a volume of 4 cc, the volume beyond which there is a risk of distant metastases. In the absence of curative treatment, a cancer diagnosed at the localized stage before the age of 65 years is associated with a specific survival of less than 30%. The median survival of metastatic prostatic cancer is 2 to 3 years. 3) The disease can be detected at an early stage. Cancers diagnosed by an isolated elevation of PSA in a screening setting have a significant volume in more than 3 out of 4 cases, can be entirely removed by prostatectomy in more than 3 out of 4 cases and have a less advanced pathological stage than cancers diagnosed on the basis of classical criteria.