Holm N V, Hauge M, Harvald B
J Natl Cancer Inst. 1980 Aug;65(2):285-98.
The Danish Twin Register consists of the total population of twin pairs born in Denmark during a certain period. Within this population were found 50 monozygotic (MZ) female twins belonging to 45 MZ pairs and 81 dizygotic (DZ) twins belonging to 77 DZ female pairs, of which at least 1 twin had breast cancer (BC) and both twins were alive at the time of the first BC diagnosis. In 5 MZ and 4 DZ pairs, both partners had BC. Pairwise concordance rates were not significantly different between the 2 groups of twins but were of the same magnitude as in a previous study. The heritability, evaluated by genetic determination, was estimated to be 0.30-0.40. The observed number of BC cases developing in the co-twins after the first BC diagnosis in the twin pairs was increased by a factor of nearly 6 in MZ co-twins and by a factor of about 2 in DZ co-twins. For cancer of other sites, the observed and expected numbers were nearly identical in both MZ and DZ co-twins. In 8 of 9 pairs concordant for BC, the lesion was found on the same side. The mean age at diagnosis showed no significant difference between the concordant and discordant pairs. In the 40 MZ pairs with only 1 twin affected, she was more often unmarried and/or nulliparous than her unaffected, genetically identical co-twin, but this finding was not significant. A general tendency for the twin with BC to have the first child at a later age than her unaffected twin sister could not be demonstrated.
丹麦双胞胎登记册涵盖了某一时期在丹麦出生的所有双胞胎。在这一群体中，发现了属于45对同卵双胞胎的50名同卵（MZ）女性双胞胎，以及属于77对异卵双胞胎的81名异卵（DZ）双胞胎，其中至少有1名双胞胎患有乳腺癌（BC），且在首次BC诊断时，两名双胞胎均在世。在5对MZ和4对DZ双胞胎中，双方均患有BC。两组双胞胎的成对一致性率无显著差异，但与之前的一项研究结果相当。通过基因测定评估的遗传度估计为0.30 - 0.40。在双胞胎对中，首例BC诊断后，同卵双胞胎中共同患BC的观察病例数增加了近6倍，异卵双胞胎中增加了约2倍。对于其他部位的癌症，同卵和异卵双胞胎的观察病例数与预期病例数几乎相同。在9对BC一致的双胞胎中，有8对病变位于同一侧。诊断时的平均年龄在一致和不一致的双胞胎对之间无显著差异。在仅1名双胞胎患病的40对MZ双胞胎中，患病的双胞胎比未患病的、基因相同的同胞双胞胎更常未婚和/或未育，但这一发现并不显著。未发现患BC的双胞胎比未患病的双胞胎姐妹生育头胎的年龄普遍偏大的趋势。
