Yuen J, Ekbom A, Trichopoulos D, Hsieh C C, Adami H O
Cancer Epidemiology Unit, Uppsala University Hospital, Sweden.
Br J Cancer. 1994 Sep;70(3):564-8. doi: 10.1038/bjc.1994.346.
Recent research suggests that intrauterine exposures, perhaps factors that influence birth weight and other indicators of fetal growth, may affect future breast cancer risk. Because birth weight shows seasonal variation in Sweden, we assessed whether risk for breast cancer is associated with month of birth. The analyses included all 115,670 women, born between 1858 and 1968, who were reported to the Swedish Cancer Registry in 1958-89 as having breast cancer. Poisson regression models were used to examine the data. After adjustment for seasonality of number of live births in the population at risk, a significant seasonal pattern was identified for women born between 1880 and 1920. Women born in June had a 5% higher risk of breast cancer than those born in December. By contrast, there was no evidence of birth seasonality among 440,948 women with cancer at other sites. Exposures relevant to breast cancer risk later in life are unlikely to be related to month of birth. Thus, prenatal or early post-natal factors influence breast carcinogenesis, but the seasonal variation in these factors must have decreased over time.
近期研究表明，子宫内暴露，或许是那些影响出生体重及其他胎儿生长指标的因素，可能会影响未来患乳腺癌的风险。由于瑞典的出生体重呈现季节性变化，我们评估了患乳腺癌的风险是否与出生月份有关。分析纳入了1858年至1968年间出生、于1958年至1989年向瑞典癌症登记处报告患有乳腺癌的所有115670名女性。采用泊松回归模型对数据进行分析。在对处于风险中的人群活产数的季节性进行调整后，确定了1880年至1920年间出生的女性存在显著的季节性模式。6月出生的女性患乳腺癌的风险比12月出生的女性高5%。相比之下，在440948名患有其他部位癌症的女性中，没有出生季节性的证据。与生命后期患乳腺癌风险相关的暴露不太可能与出生月份有关。因此，产前或产后早期因素会影响乳腺癌的发生，但这些因素的季节性变化肯定随着时间的推移而减少了。
