Does vasectomy cause XXXX ?

@entity1 @entity263 @entity5
Vasectomy is the process in which a @entity1 's vas deferens are severed, with the cut ends folded back and tied off to prevent the release of sperm from his testicles to the urethra and out of the penis. The procedure may be conducted in a doctor's office under local anesthesia, is almost 100% effective in preventing pregnancy, and leaves sexual function fully intact. Since sperm comprise less than 5% of semen, even the amount of ejaculated fluid does not change noticeably. 20% of American @entity1 over age 35 years have had a vasectomy. Despite vasectomy's simplicity and effectiveness, debate exists over whether vasectomy may increase the risk of @entity263 , the most common @entity5 in @entity1 . Two large, well-designed Harvard studies were published in 1993 in the Journal of the American Medical Association which suggest that such a relationship may exist. The two studies compared the number of @entity263 diagnoses in almost 25,000 @entity1 who had undergone vasectomy with nearly 50,000 @entity1 who had not. @entity1 who had undergone vasectomy more than 20 years earlier were almost twice as likely as their unsterilized counterparts to have been diagnosed with @entity263 . Overall, the rate of such diagnoses was about 60% higher among the @entity1 who had been sterilized. These widely-reported studies rekindled earlier fears of a possible @entity263 risk and no doubt convinced some @entity1 to avoid the operation or to have it reversed if they had already gone through with it. Four earlier studies also suggested a link between @entity263 and vasectomy. Seven other reports, however, have found no connection. Several studies even indicate that @entity1 who undergo vasectomy live longer than other @entity1 . Many researchers believe that the Harvard studies' findings are simply the result of earlier and better diagnosis of @entity263 among sterilized @entity1 rather than due to an actual increased risk of the @entity5 .
