Katayama Kayoko, Yokoyama Kazuhito, Yako-Suketomo Hiroko, Okamoto Naoyuki, Tango Toshiro, Inaba Yutaka
Cancer Prevention and Cancer Control Division, Kanagawa Cancer Center Research Institute, Japan E-mail :
Asian Pac J Cancer Prev. 2014;15(1):455-60. doi: 10.7314/apjcp.2014.15.1.455.
The purpose of the present study was to determine geographic clustering of breast cancer incidence in Kanagawa Prefecture, using cancer registry data. The study also aimed at examining the association between socio-economic factors and any identified cluster.
Incidence data were collected for women who were first diagnosed with breast cancer during the period from January to December 2006 in Kanagawa. The data consisted of 2,326 incidence cases extracted from the total of 34,323 Kanagawa Cancer Registration data issued in 2011. To adjust for differences in age distribution, the standardized mortality ratio (SMR) and the standardized incidence ratio (SIR) of breast cancer were calculated for each of 56 municipalities (e.g., city, special ward, town, and village) in Kanagawa by an indirect method using Kanagawa female population data. Spatial scan statistics were used to detect any area of elevated risk as a cluster for breast cancer deaths and/ or incidences. The Student t-test was performed to examine differences in socio-economic variables, viz, persons per household, total fertility rate, age at first marriage for women, and marriage rate, between cluster and other regions.
There was a statistically significant cluster of breast cancer incidence (p=0.001) composed of 11 municipalities in southeastern area of Kanagawa Prefecture, whose SIR was 35 percent higher than that of the remainder of Kanagawa Prefecture. In this cluster, average value of age at first-marriage for women was significantly higher than in the rest of Kanagawa (p=0.017). No statistically significant clusters of breast cancer deaths were detected (p=0.53).
There was a statistically significant cluster of high breast cancer incidence in southeastern area of Kanagawa Prefecture. It was suggested that the cluster region was related to the tendency to marry later. This study methodology will be helpful in the analysis of geographical disparities in cancer deaths and incidence.
本研究旨在利用癌症登记数据确定神奈川县乳腺癌发病率的地理聚集情况。该研究还旨在探讨社会经济因素与任何已确定的聚集区之间的关联。
收集了2006年1月至12月期间在神奈川县首次被诊断为乳腺癌的女性的发病数据。数据包括从2011年发布的34323例神奈川县癌症登记数据中提取的2326例发病病例。为了调整年龄分布差异，采用间接方法，利用神奈川县女性人口数据，计算了神奈川县56个市（如市、特别区、镇和村）中每个市的乳腺癌标准化死亡率（SMR）和标准化发病率（SIR）。空间扫描统计用于检测乳腺癌死亡和/或发病率升高风险的区域作为聚集区。采用学生t检验来检验聚集区与其他地区在社会经济变量（即每户人数、总生育率、女性初婚年龄和结婚率）方面的差异。
在神奈川县东南部地区，由11个市组成了一个具有统计学意义的乳腺癌发病聚集区（p = 0.001），其标准化发病率比神奈川县其他地区高35%。在这个聚集区中，女性初婚年龄的平均值显著高于神奈川县其他地区（p = 0.017）。未检测到具有统计学意义的乳腺癌死亡聚集区（p = 0.53）。
在神奈川县东南部地区存在一个具有统计学意义的高乳腺癌发病率聚集区。表明该聚集区与晚婚倾向有关。本研究方法将有助于分析癌症死亡和发病率的地理差异。
