Holmberg E, Holm L E, Lundell M, Mattsson A, Wallgren A, Karlsson P
The Oncological Centre, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden.
Br J Cancer. 2001 Aug 3;85(3):362-6. doi: 10.1054/bjoc.2001.1868.
Exposure to ionizing radiation is a known risk factor for breast cancer and the fertility pattern is a recognized modifier of breast cancer risk. The aim of this study was to elucidate the interaction between these 2 factors. This study is based on a Swedish cohort of 17 202 women who had been irradiated for skin haemangiomas in infancy between 1920 and 1965. The mean age at treatment was 6 months and the median breast dose was 0.05 Gy (range 0-35.8 Gy). Follow-up information on vital status, parity, age at first childbirth and breast cancer incidence was retrieved through record linkage with national population registers for the period 1958-1995. Analyses of excess relative risk (ERR) models were performed using Poisson regression methods. In this cohort, the fertility pattern differed from that in the Swedish population, with significantly fewer childbirths overall and before 25 years of age but more childbirth after that age. There were 307 breast cancers in the cohort and the standardized incidence ratio (SIR) was 1.22 (95% CI 1.09-1.36). A linear dose-response model with stratification for fertility pattern and menopausal status resulted in the best fit of the data. ERR/Gy was 0.33 (95% CI 0.17-0.53). In absolute terms this means an excess of 2.1 and 5.4 cases per Gy per 10(4) breast-years in the age groups 40-49 and 50-59 years respectively. The fertility pattern influenced the breast cancer risk in this irradiated population in a similar way to that observed in other studies. SIR at dose = 0 was highest, 2.31, among postmenopausal nulliparous women (95% CI 1.48-3.40, n = 62). SIR at dose = 0 was lowest in pre- or postmenopausal women with a first childbirth before 25 years of age; 0.89 (0.71-1.09) and 0.88 (0.58-1.25) respectively. Thus, in addition to the dose-effect response in the cohort, part of the breast cancer excess could be explained by a different fertility pattern. The estimates of ERR/Gy for the various categories of age at first childbirth, number of children, menopausal status and ovarian dose were very similar, contradicting any interaction effects on the scale of relative risk.
暴露于电离辐射是已知的乳腺癌风险因素，而生育模式是公认的乳腺癌风险调节因素。本研究的目的是阐明这两个因素之间的相互作用。本研究基于瑞典的一个队列，该队列由1920年至1965年间婴儿期因皮肤血管瘤接受过放射治疗的17202名女性组成。治疗时的平均年龄为6个月，乳腺中位剂量为0.05 Gy（范围0 - 35.8 Gy）。通过与1958 - 1995年期间的国家人口登记册进行记录链接，获取了关于生命状态、产次、初育年龄和乳腺癌发病率的随访信息。使用泊松回归方法对超额相对风险（ERR）模型进行分析。在这个队列中，生育模式与瑞典人群不同，总体上以及25岁之前的分娩次数显著减少，但25岁之后的分娩次数更多。该队列中有307例乳腺癌，标准化发病比（SIR）为1.22（95%可信区间1.09 - 1.36）。一个对生育模式和绝经状态进行分层的线性剂量反应模型对数据拟合最佳。ERR/Gy为0.33（95%可信区间0.17 - 0.53）。就绝对值而言，这意味着在40 - 49岁和50 - 59岁年龄组中，每Gy每10⁴乳腺年分别额外增加2.1例和5.4例。生育模式对这个接受过放射治疗的人群的乳腺癌风险的影响与其他研究中观察到的类似。在绝经后未生育女性中，剂量 = 时的SIR最高，为2.31（95%可信区间1.48 - 3.40，n = 62）。在25岁之前生育第一胎的绝经前或绝经后女性中，剂量 = 0时的SIR最低；分别为0.89（0.71 - 1.09）和0.88（0.58 - 1.25）。因此，除了队列中的剂量效应反应外，部分乳腺癌超额病例可以用不同的生育模式来解释。对于初育年龄、子女数量绝经状态和卵巢剂量的各类别，ERR/Gy的估计值非常相似，这与相对风险尺度上的任何相互作用效应相矛盾。
