Adenocarcinoma of the prostate in Iceland: a population-based study of stage, Gleason grade, treatment and long-term survival in males diagnosed between 1983 and 1987.

OBJECTIVE: To investigate adenocarcinoma of the prostate in a single population with an extended follow-up period.
MATERIAL AND METHODS: Using the Icelandic Cancer Registry, we identified all Icelandic men diagnosed with prostate cancer between 1983 and 1987. Disease stage, initial treatment and follow-up information were obtained from hospital records and death certificates. A critical evaluation was made of the accuracy of the death certificates regarding prostate cancer. All available histology information was reviewed and graded according to the Gleason grading system.
RESULTS: A total of 414 men were diagnosed with adenocarcinoma of the prostate. Of these, 370 were alive at the time of diagnosis and stage could be determined. Four stage groups were defined: focal incidental (n=50); localized (n=164); local advanced (n=32); and metastatic disease (n=124). The mean age at diagnosis was 74.4 years (range 53-94 years). The combined Gleason score was 2-5 in 89, 6-7 in 117, 8-10 in 117 and unknown in 47 cases. The median follow-up period for the group was 6.15 years (range 0.3-19.8 years). Thirty men received treatment with curative intent: radiation therapy, n=20; and radical prostatectomy, n=10. A total of 334 patients died during the follow-up period, of whom 168 (50%) died of prostate cancer. Prostate cancer-specific survival at 10 and 15 years was 100% and 90.6%, respectively for focal incidental cancer; 73.1% and 60.8% for men with localized disease; 23.4% and 11.7% for local advanced disease; and 6.81% and 5.45% for metastatic disease. A Cox multivariate analysis showed age, stage and Gleason score to be independent predictors of prostate cancer death. A total of 104 patients with localized disease and a Gleason score of <or=7 received deferred treatment. The cause-specific survival for this group was 95.6%, 86.5% and 79.2% at 5, 10 and 15 years, respectively. Death certificates were judged to be accurate with regard to prostate cancer in nearly all instances (96%).
CONCLUSIONS: During an extended follow-up period, half of all patients with prostate cancer died from the disease. Males with localized disease and a favorable tumor grade fared well with deferred treatment. However, a higher stage and grade were associated with substantial prostate cancer mortality. Death certificates were accurate as far as prostate cancer was concerned.