Purpose: The possibility was investigated whether obesity is associated with a favorable prognosis in men with nonstage A prostatic cancer independent of other risk factors.
Materials and methods: A total of 235 men with nonstage A prostatic cancer diagnosed between 1983 and 1990 at a community hospital was evaluated by tumor grade and stage, degree of obesity, smoking habits, age, year of diagnosis and survival.
Results: In comparison to tumors of less obese men those in men who were at least 10% overweight were more often stage B or C than D (odds ratio 2.3, 95% confidence interval 1.4 to 4.9). Smoking abstinence, patient age older than 70 years and low Gleason scores were also independently associated with less advanced tumors. The lower frequency of advanced stage tumors among those of obese men was most prominent for stage D2 disease in nonsmokers, progressively decreasing from 24% of 29 nonsmokers who had been underweight for many years before diagnosis to 8% of 24 who had been greatly overweight for many years (p < 0.05). Tumor specific mortality was also lower in obese men and nonsmokers independent of tumor stage and grade with 5-year tumor specific mortality rates of 10% in obese nonsmokers, 27% in nonobese nonsmokers, 36% in obese smokers and 43% in nonobese smokers. These differences reflected a combination of obesity related differences in stage distribution and a more favorable prognosis for obese men among patients with tumors of similar stages.
Conclusions: These observations suggest inhibition of prostate cancer growth and metastasis by increased endogenous estrogen, decreased endogenous testosterone or other systemic changes characteristic of obesity.