BACKGROUND:In a large number of studies a positive family history is documented as one of the main risk factors for the development of prostate cancer. In a US population an association between early-onset prostate cancer among familial patients and a more differentiated tumour was shown. The aim of this study was to compare clinical parameters between sporadic and familial or hereditary patients with an age at diagnosis < or =55 years. MATERIAL AND METHODS:The clinical data of prostate cancer patients with an age at diagnosis < or =55 years and who were recruited between July 1999 and the end of June 2004 to the database "familial prostate cancer in Germany" were analysed. The following data were documented for all patients: PSA at diagnosis, histopathological stage, grading, Gleason score and progression-free survival. RESULTS:The clinical data of 685 patients could be completed: 222 (32.4%) had one first-degree relative with prostate cancer, 48 of whom (7.0%) were hereditary; 463 (67.6%) were sporadic. The median age at diagnosis in the hereditary patients was 51.6 (41-55) years, in the familial patients 51.1 (35-55) years and in the sporadic patients 52.0 (38-55) years. The median follow-up was 24 months in hereditary, 36 months in familial and 35 months in sporadic patients. An initial curative therapy with radical prostatectomy or radiotherapy/brachytherapy was planned in 657/685 (95.9%) of the patients. There were no clear differences regarding PSA at diagnosis, the postoperative parameters (organ-confined disease, lymph node involvement, Gleason score, grading) and the progression-free survival in sporadic and familial or hereditary patients. CONCLUSIONS:Patients with an age at diagnosis < or =55 years have a positive family history more often than all prostate cancer patients in Germany. No association could be shown between pathohistological stage or clinical course and a positive family history in patients with an age at diagnosis < or =55 years.