PROSTATE CANCER IN RELATION TO VASECTOMY

尽管前列腺癌（PC）是第二常见的 癌症是美国男性的第三大癌症原因 死亡率，相对较少的流行病学研究，这种疾病有 其病因学知之甚少。最近的一个案例- 对照研究表明输精管结扎术可能与AS有关 患前列腺癌的风险会增加两到四倍。病例对照 将在70岁以下男性中进行与输精管切除术相关PC研究， 在马萨诸塞州进行：1128名最近诊断为PC的男性将 相比之下，年龄匹配的邻居对照组的人数是对照组的两倍。信息 输精管切除术和潜在混杂变量将通过以下方式获得 个人访谈和自我管理的食物频率问卷。 因为很少有男性选择输精管结扎术作为避孕方法之前， 1960年，第一批输精管切除的男性直到现在才被发现。 达到PC高发年龄。这项研究将提供重要的 关于日益普遍和可改变的接触的信息， 输精管结扎术，这可能会增加PC的发病率。 本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、既往药物使用、其他 医疗条件和职业对PC的风险。 为了评估选择偏差的可能性，将分析病例 根据诊断时的临床分期（疾病限于 前列腺、延伸到前列腺以外的疾病）。例局部 广泛性或转移性疾病对选择偏倚不太敏感 因为症状会让他们去就医， 既往病史。既往有PC病史或症状的男性 可能是由于未诊断的PC（例如，夜间活动频繁， 未诊断的腰痛）将从对照系列中排除， 实际上保证了一组没有晚期前列腺疾病。因为 PC在老年男性中的高患病率，仍然有可能， 对照组中的一些男性会有未确诊的无症状的 然而，他们将没有晚期的、有症状的肿瘤。到 对照系列包括患有小的，未诊断的PC的男性 病变，晚期PC与输精管切除术的正相关性将 表明输精管切除术至少与以下风险增加有关： 晚期或侵袭性PC，但输精管结扎术对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.