Familial risks for testicular cancer (TC) are among the highest of all cancers. However, data are limited for histological types of TC and for possible familial associations of TC with other cancers. We used the nationwide Swedish Family-Cancer Database for years 1958 to 2015 to analyse familial relative risks (RR) for 11,138 TC patients when first-degree relatives were diagnosed with TC or other cancer in reference to those without a family history. A total of 191 familial TCs were found, which accounted for 2.0% of all TC. The RR was 5.06 when one family member was diagnosed with TC with no significant difference between seminoma and nonseminoma. However, the risk for nonseminoma was 33.59 when two family members were affected. Internally consistent familial associations of TC, particularly of seminoma, were found with breast and nervous system cancers and melanoma. Individual significant associations were found for a number of sites, including ovarian, endometrial and prostate cancers. Our results suggest that nonseminoma may have a stronger genetic background than seminoma but seminoma shares more familial associations with discordant cancers. Clustering of TC with hormone-dependent cancers of the breast, ovary, endometrium and prostate may suggest mechanistic links and possibly gene-environment interactions.

中文翻译：

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睾丸癌与其他癌症的家族关系。

睾丸癌（TC）的家族风险是所有癌症中最高的。但是，关于TC的组织学类型以及TC与其他癌症的家族联系的数据有限。我们使用了1958年至2015年的全国瑞典家庭癌症数据库，对没有亲属史的一级亲属被诊断为患有TC或其他癌症的11138名TC患者进行了家庭相对风险（RR）分析。共发现191个家族性TC，占所有TC的2.0％。当一名家庭成员被诊断为TC时，精原细胞瘤和非精原细胞瘤的RR为5.06。但是，当两名家庭成员受到影响时，非精原细胞瘤的风险为33.59。TC（特别是精原细胞瘤）的内部一致家族关联，被发现患有乳腺癌和神经系统癌症以及黑色素瘤。在许多部位发现了个体显着的关联，包括卵巢癌，子宫内膜癌和前列腺癌。我们的研究结果表明，非精原细胞瘤的遗传背景可能比精原细胞瘤更强，但精原细胞瘤与不和谐癌症有着更多的家族联系。TC与乳腺癌，卵巢癌，子宫内膜癌和前列腺癌的激素依赖性癌症有关，可能提示机制相关，也可能与基因-环境相互作用有关。