Tulinius H, Sigvaldason H, Hrafnkelsson J, Olafsdóttir G, Tryggvadóttir L, Sigurösson K
Icelandic Cancer Society, Reykjavik.
Int J Cancer. 1990 Dec 15;46(6):972-5. doi: 10.1002/ijc.2910460604.
In a previous prospective study we showed elevated risks for breast cancer in nulliparous women compared to parous women, in those having their first pregnancy at a higher age, and those with few children. This was based on 216 women diagnosed with breast cancer during 1965 to 1975 among 34,525 women having attended the cervix cancer detection clinic in Iceland by the end of 1974, and born between 1906 and 1945. The present investigation on 848 cases, diagnosed among 61,040 women attending the cervix cancer detection clinic during 1964 to 1984 and born between 1901 and 1960, shows the same risk factors to be significant. The relative risks are, however, smaller. The reasons for the difference in relative risks are discussed. We find that the effect of age at first birth is significant for women up to the age of 65 and not for older women. In both cohorts, women older than 55 are underrepresented and more so in the earlier report. In addition, the small number of cases in the reference group with age at first birth below 20 appears to have made the figures of our earlier report unreliable.
在之前的一项前瞻性研究中，我们发现，与经产妇相比，未生育女性、首次怀孕年龄较大的女性以及子女较少的女性患乳腺癌的风险更高。这一结论基于1965年至1975年间在冰岛宫颈癌检测诊所就诊的34525名女性中的216例乳腺癌确诊病例，这些女性出生于1906年至1945年之间，截至1974年底在该诊所就诊。本次调查涉及1964年至1984年间在宫颈癌检测诊所就诊的61040名女性中的848例确诊病例，这些女性出生于1901年至1960年之间，结果显示相同的风险因素具有显著性。然而，相对风险较小。本文讨论了相对风险存在差异的原因。我们发现，首次生育年龄的影响在65岁及以下的女性中具有显著性，而在年龄较大的女性中则不然。在这两个队列中，55岁以上的女性所占比例较低，且在早期报告中更为明显。此外，首次生育年龄低于20岁的参考组病例数量较少，这似乎使得我们早期报告中的数据不可靠。
