PROSTATE CANCER IN RELATION TO VASECTOMY

尽管前列腺癌(PC)是第二常见的癌症 美国男性中的癌症和第三大致癌原因 死亡率，这种疾病的流行病学研究相对较少。 已经进行了研究，但对其病因知之甚少。最近的一起案件- 对照研究表明，输精管结扎术可能与AS有关 患PC的风险增加了两到四倍。病例对照 70岁以下男性中PC与输精管结扎术的关系的研究将是 在马萨诸塞州进行的一项调查：1128名最近被诊断为PC的男性将被 相比之下，年龄匹配的邻居对照组的数量是对照组的两倍。信息 关于输精管结扎术和潜在的混杂变量将通过 个人访谈和自填式食物频率调查问卷。 因为很少有男性选择输精管结扎术作为避孕方法 1960年，第一批接受输精管结扎术的男性直到现在 达到PC高发年龄。这项研究将提供重要的 关于日益普遍和可修改的暴露的信息， 输精管结扎术，可能会增加PC的发生率。 这项研究的次要目的是评估其他因素的影响 (混杂因素)如性史、饮食、既往吸毒史、其他 医疗条件，以及个人电脑风险的职业。 为了评估选择偏差的可能性，将对案例进行分析 根据诊断时的临床阶段分别进行(仅限于 前列腺，疾病延伸到前列腺以外)。本地感染病例 广泛性或转移性疾病不太容易受到选择偏差的影响 因为症状会让他们去看医生，不管 以前的病史。有PC病史或症状的男性 可能是由于未诊断的PC(例如，夜间频率过高， 未诊断的腰背痛)将被排除在对照系列之外， 几乎确保了一组人没有晚期前列腺病。因为 在老年男性中PC的高流行率中，仍然有可能 对照组中的一些男性会有未确诊的，无症状的 PC；然而，他们将不会有晚期的有症状的肿瘤。发送到 对照系列包括患有小型、未诊断PC的男性的范围 病变，晚期PC与输精管结扎术的正相关将 表明输精管结扎术至少与增加的风险有关 进展期或侵袭性PC但输精管结扎对PC发生率的影响 可能被低估了。

Despite the fact that prostate cancer (PC) is the second most common cancer among American men and the third leading cause of cancer mortality, relatively few epidemiologic studies of this disease have been conducted, and little is known about its etiology. A recent case- control study has suggested that vasectomy may be associated with as much as a two to four fold increase in the risk of PC. A case-control study of PC in relation to vasectomy among men under age 70 will be conducted in Massachusetts: 1128 men with recently diagnosed PC will be compared with twice as many age-matched neighbor controls. Information on vasectomy and potential confounding variables will be obtained by personal interview and a self administered food frequency questionnaire. Because few men chose vasectomy as a method of contraception prior to 1960, the first substantial cohort of vasectomized men is only now reaching the age of high PC incidence. This study will provide important information on an increasingly common and modifiable exposure, vasectomy, that may increase the incidence of PC. Secondary aims of this study are to evaluate the effect of other factors (confounders) such as sexual history, diet, prior drug use, other medical conditions, and occupation on PC risk. To assess the possibility of selection bias, cases will be analyzed separately according to clinical stage at diagnosis (disease limited to the prostate, disease extending beyond the prostate). Cases with locally extensive or metastatic disease are less susceptible to selection bias because symptoms will bring them to medical attention irrespective of prior medical history. Men with a prior history of PC or symptoms possibly due to undiagnosed PC (e.g., excessive nocturnal frequency, undiagnosed low back pain) will be excluded from the control series, virtually assuring a group free of advanced prostatic disease. Because of the high prevalence of PC in elderly men, it remains possible that some of men in the control series will have undiagnosed, asymptomatic PC; they will, however, be free of advanced, symptomatic tumors. To the extent that the control series includes men with small, undiagnosed PC lesions, a positive association of advanced PC with vasectomy will indicate that vasectomy is at least associated with an increased risk of advanced or aggressive PC but the effect of vasectomy on PC incidence may be underestimated.