Smoking and obesity in relation to the etiology and disease progression of prostate cancer in Japan.

BACKGROUND: Various risk factors have been investigated concerning the etiology of prostate carcinoma, but many questions about the significance of the risk factors remain unanswered. To evaluate the relationship between smoking and obesity in prostate cancer, a case-control study was performed.
METHODS: Between 1986 and 1995, 329 patients with untreated prostate cancer and 188 patients with benign prostate hyperplasia (control patients) were evaluated according to their smoking habits and the degree of obesity. Also, the progression of prostate cancer in relationship to smoking and obesity was examined.
RESULTS: Smoking and obesity were not risk factors for the development of prostate cancer (odds ratio, 0.986, 0.836; 95% confidence interval, 0.69-1.41, 0.57-1.24, respectively). Nor were smoking or obesity a risk factor for survival in stage D2 patients, however, in stage B1-D1 patients, obese men had a tendency for disease progression.
CONCLUSION: This study demonstrated that neither smoking nor obesity increase the risk of developing prostate cancer, or the risk of disease progression in prostate cancer patients. However, obese men have a tendency for progression of stage B1-D1 prostate cancer although further studies are necessary to confirm this finding.