Grand multiparity and the risk of breast cancer:: population-based study in Finland
Grand multiparity and the risk of breast cancer:: population-based study in Finland
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DOI：
10.1023/a:1011253527605
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发表时间：
2001-08-01
影响因子：
2.3
通讯作者：
Kauppila, A
中科院分区：
文献类型：
--
作者：
Hinkula, M;Pukkala, E;Kauppila, A
目的：到目前为止，生殖因素对乳腺癌风险的重要性一直被描述为具有最高胎次的5胎的人群。我们通过评估胎次、初产年龄和平均生育间隔对乳腺癌风险的重要性，将这些研究扩展到全国范围内至少有五个孩子的女性(大经产妇=GM)。方法：研究队列来自芬兰人口登记处，包括86,978名GM女性；癌症病例的发病率来自以人口为基础的芬兰癌症登记处。在大约200万人年的随访中，共获得1508例乳腺癌。结果：GM队列中乳腺癌发病率较低(SIR为0.55，95%可信区间为0.52-0.58)。相对风险从5-PARS(SIR 0.60，经其他研究变量调整)显著降低至8-PARS(SIR 0.40)。初次生育年龄从不到20岁增加到30岁以上，风险几乎翻了一番(SIR从0.40增加到0.73)。只有在导管癌中，产次才是一个重要的风险决定因素，而缩短出生间隔只在小叶癌中有保护作用。转基因妇女晚期乳腺癌的发病率高于绝经前妇女和30岁以上首次生育妇女的发病率。结论：首次生育年龄小和生育次数增加是从第五个孩子开始的独立和强大的保护因素，而出生间隔在这方面较弱。肿瘤形态和恶性肿瘤的临床进展改变了乳腺癌风险对生殖变量的依赖。
Objectives: The significance of reproductive factors on breast cancer risk has so far been characterized in populations with 5-paras as the highest category of parity. We extended these studies to a nationwide cohort of women with at least five births (grand multiparas = GM) by assessing the significance of parity, age at first birth, and average birth interval to the risk of breast cancer.Methods: The study cohort obtained from the Population Register of Finland comprised 86,978 GM-women; the incidence of cancer cases was obtained from the populated-based Finnish Cancer Registry. During a follow-up of about 2 million person-years, 1508 breast cancers were obtained. Standardized incidence ratios (SIRs) were calculated by dividing the number of observed cases by the number expected on the basis of national rates.Results: In the GM cohort the incidence of breast cancer was low (SIR 0.55, 95% confidence interval 0.52-0.58). The relative risk decreased significantly from 5-paras (SIR 0.60, adjusted for the other study variables) to 8-paras (SIR 0.40). The increase in the age at first birth from less than 20 years to 30+ years nearly doubled the risk (SIR from 0.40 to 0.73). Parity was a significant risk determinant only in ductal cancer, while shortening the birth interval was protective only in lobular cancer. The incidence of advanced breast cancer among GM-women exceeded the population rate in premenopausal women and in women with first birth at the age of 30 years or more.Conclusions: Our study demonstrated that young age at first birth and increasing number of births were independent and powerful protective factors from the fifth child onwards, while birth interval was weak in this respect. The tumor morphology and the clinical advancement of malignancy modified the dependence of breast cancer risk on reproductive variables.