Early initiation of shaving and sexual activity as risk factors for prostate cancer

Abstract

Purpose: Prostate cancer is the most common nonskin malignancy and the second leading cause of cancer deaths among men in the United States. Prostate cancer has a complex etiology; presently, age, ethnicity, and family history are the most consistently reported risk factors associated with disease. Other potential risk factors have also been suggested. The aim of this study was to identity a potential relationship between early onset of shaving initiation and first sexual activity in the development of prostate cancer. We also examined the pathologic stage, Gleason sum, and age of prostate cancer diagnosis in relation to early onset of shaving initiation and first sexual activity in the development of prostate cancer. Materials and Methods: This study was designed as a retrospective case-control study. 167 veterans referred for prostate needle biopsy, due to an elevated PSA or abnormal DRE, to evaluate for the presence of prostate cancer, during a 31-month period completed questionnaires. 7 4 cases were identified from the group as having prostate cancer, as evidenced by a positive prostate biopsy. 93 veterans from the group were identified as not having prostate cancer, as evidenced by at least one negative prostate biopsy. Assessment of exposed and non-exposed members of the group was accomplished by their responses to the questionnaire querying their age at initiation of shaving and age they became sexually active. The age responses to the shaving and sexual activity questions were divided into tertiles with the youngest tertile considered the "exposed" population with early onset of hormonal influences. The risk of prostate cancer was modeled using Binary Logistic Regression Analysis. Additional analyses usmg X 2 • two-sample !-tests, Univariate Analysis of Variance, and Log Linear equations were conducted to determine differences in means for individual variables. Variables examined included age of prostate cancer diagnosis, race, PSA levels, DRE findings, Gleason sum, pathologic stage, height, weight, BMI, age of shaving initiation and first sexual activity. Results: Of the 35 early onset of shaving exposed patients 13 (3 7.1%) had prostate cancer, while 22 (23.7%) did not. There was no increased risk of early onset of shaving with cancer in exposed (p = 0.513). Of the 42 early age of first intercourse exposed patients 20 (27%) had prostate cancer, while 22 (52.4%) did not. There was no correlation of early age of first intercourse with cancer in exposed (p = 0.882). PSA levels demonstrated a statistically significant difference between the groups (p = 0.007) by Jt- and two-sample !-tests. There was a significant difference in the mean age of diagnosis of prostate cancer for Caucasians (64.8) and African Americans (59.9). We also found partial associations between age of first sex category by race category (P=0.0233) and age of first sex category by family history category (P=.0493). Conclusions: We found no significant increased risk of prostate cancer in veterans referred for prostate biopsy who reported an early onset of shaving initiation and an early age at first sexual activity.· Rising PSA was found to be the strongest predictor of prostate cancer in our population. We also found no statistically significant differences in mean pathologic stage, Gleason sum, or age of prostate cancer diagnosis for age of first shave and age of first sex. We identified a significant difference in the mean age of diagnosis for Caucasians (64.8) and African Americans (59.9). We also found partial associations between age of first sex category by race category and age of first sex category by family history category in relation to pathologic stage. Although higher or earlier peaks in pubertal androgen levels may contribute to the relation of early onset of shaving, early age of first intercourse and prostate cancer, our data did not support this. Additional research will be required to further evaluate the conflicting results of past research in regards to hormone levels and the incidence of prostate cancer.