ASCO 2013：输精管结扎术可增加前列腺癌患者死亡风险

　　美国学者的一项研究显示，输精管结扎术与前列腺癌高度病变发生、疾病致死或骨转移的增加相关。

　　该前瞻性研究在1986年纳入49,432名男性进行随访，直到2010年，了解其癌症发生率和死亡率；发现其中6,398例被诊断为前列腺癌，包括734例高度病变(Gleason评分为8-10) 和813例癌症致死或骨转移（致命）。我们用cox 回归模型计算输精管结扎术与高度病变发生、前列腺癌致死之间的关系。

　　结果显示，初始22%男性做过输精管结扎术，这部分人群发生高度病变的风险（HR 1.23, 95% CI:1.04-1.47）和前列腺癌骨转移（HR 1.20, 95% CI: 1.01-1.43）均增加。与38岁以后做输精管结扎术的男性比较， 38岁前做过输精管结扎术的男性导致前列腺癌致死的风险更高。且该风险的增加可能不能通过荷尔蒙水平差异、性传播疾病的发生或癌症治疗来解释。

Vasectomy and risk of lethal prostate cancer: A 24-year prospective study.
Background
In the United States, 10 to 15 percent of adult men have undergone a vasectomy. There is conflicting evidence whether vasectomy is associated with increased prostate cancer risk.
Methods
We undertook a prospective study among 49,432 men in the US Health Professionals Follow-up Study. The men were age 40 to 75 years at baseline in 1986 and were followed prospectively for cancer incidence and mortality through 2010; 6,398 incident cases of prostate cancer were diagnosed, including 734 with high grade (Gleason 8 – 10) and 813 with cancer causing death or bony metastasis (lethal). We used cox regression models to calculate hazard ratios (HR, 95% confidence intervals) of the association between vasectomy and incidence of high grade and lethal prostate cancer, adjusting for potential confounders. We examined associations in the total cohort, and in a subset of 12,371 men highly screened by PSA in order to disentangle potential diagnostic bias.
Results
At baseline, 22 percent of men reported having had a vasectomy. Men who had undergone vasectomy were at increased risk of high-grade (HR 1.23, 95% CI: 1.04-1.47) and lethal (HR 1.20, 95% CI: 1.01-1.43) prostate cancer. In the highly screened cohort, the association was similar for high-grade cancer, and even stronger for lethal disease (HR 1.56, 1.03-2.36). The risk of lethal prostate cancer was higher among men who had a vasectomy before age 38 years compared to at older ages. The increased risks with vasectomy could not be explained by differences in hormone levels, prevalence of sexually transmitted infections, or cancer treatments.
Conclusions
Data from this study support the hypothesis that vasectomy is associated with a small increased incidence of aggressive prostate cancer defined as high grade cancer and disease causing death or bony metastasis. Differences in diagnostic intensity or confounding bias do not explain this elevated risk.