#1 – Does Vasectomy Cause Prostate Cancer?
No! In the June 1999 issue of the Journal of Urology, Dr. Samuel Lesko and associates from the Boston University School of Medicine report the results of their epidemiologic studies which once again failed to demonstrate an association between previous vasectomy and subsequent development of prostate cancer. Both in this scientific article and in the accompanying editorial comment by Professor Stuart Howards from the Department of Urology of the University of Virginia School of Medicine, a detailed review is provided for the reader of what is now an extensive body of published scientific data which convincingly shows that vasectomy does not cause prostate cancer.#2 – News – Efficacy of Viagra to treat Impotence after prostate brachytherapy.A scientific study by Dr. Gregory Merrick and associates using the drug sildenafil citrate (commonly known as Viagra) to treat erectile impotence in men who had previously undergone prostatic brachytherapy for localized prostate cancer has been reported.
They note that erectile dysfunction may occur in up to 50 percent of men undergoing this form of radiation treatment for prostate cancer.
In their study, they treated 62 men who were impotent after brachytherapy, and found that 50 of these individuals (81 percent) were able to have successful erections using Viagra at a dose of either 50 or 100 milligrams. These results are equivalent to the results reported for use of Viagra by men with erectile dysfunction who have not had prostate cancer or brachytherapy. In other words, they found that Viagra is an effective treatment which works just as well for men who are impotent after prostaticbrachytherapy as it does for all other impotent men. #3 – News – New Help for Hot Flashes following Hormonal Therapy A group of researchers from the Mayo Clinic reported their results using a new drug to relieve hot flashes in men undergoing androgen ablation hormonal therapy for prostate cancer. The new drug, Venlafaxine (also known by the brand name Effexor), produced significant relief of hot flash symptoms. Very low doses of this medication were used to achieve this effect–12.5 mg taken orally twice a day. Both the frequency of hot flashes and the severity of hot flash symptoms were decreased in men taking Venlafaxine. The most common side effect of the medication was nausea, which prompted 2 of 21 men in the study (9.5 percent) to stop taking the medicine. Venlafaxine compares favorably with other drugs which are usedto treat hot flashes, including Clonidine (Catapres) and Megestrol Acetate (Megace).
Vitamin EThere was a study reported in the Journal of the National Cancer Institute in 1996 about Alpha-Tocopherol (prevalent form of Vitamin E) in which approximately 30,000 men who smoked five or more cigarettes per daily were randomly assigned to receive Vitamin E, Carotene, a combination of the two or a placebo. This study found an increase in lung cancer risk among men who took beta-carotene. HOWEVER, this study also found that lung cancer risk was not decreased with Vitamin E administration. Here is the interesting part of this study by Albanes et al. there was a substantial 33% reduction in prostate cancer risk in this same group of men.Hormonal Prevention of Prostate Cancer The 5 alpha reductase inhibitor, finasteride, or PROSCAR, is being tested in the US National Cancer Institute clinical cooperative groups in the Prostate Cancer Prevention Trial (hereby referred to as the PCPT) which began in 1993. Importantly it has been demonstrated that stimulation of androgens (testosterone and dihydrotestosterone in particular) is very important in the development of prostate cancer. In fact, it is the dihydro form of testosterone or DHT, which is the principal androgen responsible for prostatic growth. DHT is 10 times more powerful than testosterone as an androgen. Studies by Trachtenberg (European Urology 1996), and Bologna (Urology 1995) have shown that suppression of DHT synthesis activity, may inhibit carcinogenic transformation of prostate cells!Several animal studies have demonstrated that finasteride, or PROSCAR, can prevent or slow the growth of prostate cancer. These results were published by Tsukamoto, et al in the Journal of the National Cancer Institute in 1995, and by Homma et al, in the same journal in 1997.
Finasteride, or PROSCAR inhibits the enzyme that converts testosterone to DHT.
It has a very good safety profile. It has been approved by the FDA for treatment of benign enlargement of the prostate, (BPH), and for the treatment of male pattern baldness. At a dose of 5mg/day of finasteride or PROSCAR, serum DHT is reduced by 75% and intraprostatic DHT is reduced by 80%.The Division of Cancer Prevention and Control of the National Cancer Institute developed a randomized trial to determine if finasteride could prevent the development of prostate cancer. Men over age 55 were enrolled. All men were felt to be free of disease at the time of enrollment. These men all had normal digital rectal examinations and total PSA’s less than 3. Following patient consent, a three-month placebo run in was begun to make sure that patients had no toxicity. As long as no side effects were encountered, randomization was done in which a man took either finasteride at 5mg/day or a placebo.On an annual basis, PSA and digital rectal exam were done. If a man in the placebo group had a PSA that rose to over the high limit normal value above 4, he had a prostate biopsy. In the finasteride group, any man that had an “indexed” PSA had a prostate biopsy, so that AN EQUAL PROPORTION OF PARTICIPANTS in both groups underwent prostate biopsy.After SEVEN years of involvement in this study, every man will undergo prostate biopsies. The goal simply is to determine the number of cumulative positive prostate biopsies over 7 years, and to see if this so called PERIOD PREVALENCE, is reduced by finasteride. This Prostate Cancer Prevention Trial was begun in October of 1994. By October of 1997, 18,000 men had enrolled in the study. Final results will be available in 2004. By many accounts, this study will provide researchers with a great amount of information for future studies for many years to come. This study is both important and tremendously exciting.