Epidemiologic study for occupational bladder cancer in Japan.

本研究的目的是估计联苯胺和-萘胺的潜在致癌期。此外，本研究重新考虑了对从事这些化学品制造过程的染料工人进行持续密切监测的重要性。在这项研究的第一年，我们调查了一组在1962年至1996年期间接触这些染料的236名染料厂工人膀胱癌的发病率。19名工人（8.1%）发现膀胱癌。这19例肿瘤的暴露期为82.0(S)。D: 50.2个月。从受试者最初和最终接触到肿瘤发生的潜伏期为29.5(S)。博士：8.2年，博士：20.1年: 1 o。6)年。值得注意的是，暴露期与从暴露结束到癌症发病的潜伏期之间呈负相关（Pearson） （R=-0.544, p< 0.05）。这些化学物质的潜伏期比预期的要长，因此，接触这些物质的工人必须继续接受密切检查。此外，尿细胞学被认为是有价值的检测和监测膀胱肿瘤。第二年，我们使用接触染料的3109名男性的数据估计潜伏期。首先，我们用Kaplan-Meier方法计算膀胱癌的累积发病率，并绘制其与潜伏期的关系图。其次，我们通过改变上界，将logistic曲线反复拟合到散点图中（即累积发病率与潜伏期之间的关系）。我们决定logistic曲线的上界，相关系数显示最大值的地方表示潜伏期最长。接触BZ引起的膀胱癌的最长潜伏期估计为51.3年。根据比例风险模型分析，确认暴露时间和初次暴露年龄会增加膀胱癌的风险。

The purpose of this study is to estimate the latent carcinogenic period of benzidine and beta-naphthylamine. Furthermore, this study reconsiders the importance of continuous close surveillance for the dyestuff workers who engaged in the manufacturing process of these chemicals.In the first year of this study, we surveyed the incidence of bladder cancers in a group of 236 dyestuff plant workers who had been exposed to these dyestuffs from 1962 to 1996. Nineteen workers (8.1%) were found to have bladder cancers. The exposure period for these 19 tumor developments was 82.0(S.D : 50.2) months. The latent period from the subjects' initial and final exposure until tumor development was 29.5(S.D : 8.2) years and 20.1(S.D. : 1O.6) years respectively. Significantly, a negative correlation (Pearson) was observed between the exposure period and the latent period from the end of exposure to cancers' onset (R=-0.544, p<O.O5). Latent periods of these chemicals were longer than expected, and therefore, exposed workers must continue to be closely examined. Also, urine cytology is thought to be valuable for detecting and monitoring bladder tumors.In the second year, we estimated the latent period using the data of 3109 men exposed to the dyestuffs. Firstly, we computed the cumulative incidence of the bladder cancer using Kaplan-Meier method, and plotted it against latency period. Secondly, we fitted the logistic curves to the scatter plot (i.e., to the relationship between cumulative incidence and latency period) repeatedly by varying the upper bounds. We decided that the upper bound of logistic curve where the correlation coefficient showed the highest value indicated the longest latency period. The longest latent period of bladder cancer caused by exposure to BZ was estimated at 51.3 years.According to proportional hazards model analysis, exposure period and age at the initial exposure were confirmed to raise the risk of bladder cancer.