JAMA:最新研究发现22种癌症属于遗传疾病
全球肿瘤医生 · 2016/01/18
哈佛大学科学家与丹麦和芬兰研究员合作进行的研究发现,至少有22种癌症属于遗传疾病,会在家族之间世代相传。根据这项大型研究的结果,大约三分之一的癌症是遗传的。家族遗传风险最高的包括前列腺癌、乳腺癌、肺癌和肠癌。


哈佛大学科学家与丹麦和芬兰研究员合作进行的研究发现,至少有22种癌症属于遗传疾病,会在家族之间世代相传。

根据这项大型研究的结果,大约三分之一的癌症是遗传的。家族遗传风险最高的包括前列腺癌、乳癌、肺癌和肠癌。科学家发现,如有同胞手足得这些癌症,其他兄弟姊妹得同样癌症的风险会提高33%。这是有史以来规模最大的历时最长的研究遗传与癌症之间关系的研究。研究发现不同的癌症, 遗传风险也不同。其中黑色素瘤和睾丸癌与遗传的关系最为密切。

总体的研究结果并不令人惊讶,而是进一步证实了早先的研究结果,即约1/3的癌症病例是由于基因缺陷引起的,其余的大多数归咎于所谓的生活方式因素,如吸烟、饮食和运动。

不同类型的癌症,遗传风险不同

由哈佛公共卫生学院Lorelei Mucci领导的研究小组在美国医学协会杂志上报道,目前发现约38%的肾脏癌、31%的乳腺癌、27%的子宫癌、58%的黑色素瘤、57%的前列腺癌和39%的卵巢癌与遗传有关。

研究人员表示,超过8%的儿童癌症患者家族中存在意料之外的的基因突变。这些突变不仅使孩子们在未来存在癌症的风险,也可能意味着他们的父母、兄弟姐妹也有一个非常高的患癌风险。Jude儿童研究医院的孟菲斯认为,研究结果不仅用新的方法来检测孩子和他们的家属存在的癌症风险,也可能会找到更好的方法来治疗他们。

这项研究从1943到2010年,对瑞典、挪威、丹麦和芬兰的20多万对双胞胎进行追踪调查,对每个人平均追踪32年。这种大规模双胞胎研究,使科学家得以评估遗传因素对癌症的重要性,并借着衡量同卵和异卵双胞胎的基因异同,评估家族罹癌风险。同卵双胞胎的基因是完全相同的,而异卵双胞胎的基因只是相似,所以这两者中患癌风险的差异明确指向为遗传因素。

Mucci的研究小组还发现,有38%的同卵双胞胎和26%的异卵双胞胎被诊断为癌症。当双胞胎中的其中一人确诊患癌后,另一人患癌的风险会显著增加,异卵双胞胎的风险为37%,而同卵双胞胎的风险则高达46%。南丹麦大学的Jacob Hjelmborg说:“由于本次研究规模庞大,跟踪时间长,我们可以看到关键基因对多种类型癌症的影响。”

睾丸癌的遗传风险很高。如果一个人的异卵双胞胎兄弟患有睾丸癌,那么他患睾丸癌的风险会增加12倍。而对同卵双胞胎来说,一人患睾丸癌,另一人患睾丸癌的风险则会增加28倍。

调查小组还发现:大约1%的人得到了黑色素瘤,这是皮肤癌的最致命的形式。如果异卵双胞胎中一人患有黑色素瘤,另一人患黑色素瘤的风险为6%,而对同卵双胞胎来说,另一人患黑色素瘤的风险为20%。

患前列腺癌和乳腺癌的风险可能是由于他们小时候共处在一个子宫内,两者都强烈地受到激素的影响,包括那些影响胎儿生长的激素。肺癌受环境影响较大,可能是由于双胞胎的吸烟习惯大多相同。

需要注意的是,在参加了该项研究的北欧国家中,癌症是引起死亡的第一大原因。在美国及其他发达国家中,癌症是引起死亡的第二大原因,仅次于心脏病。

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  • Familial Risk and Heritability of Cancer Among Twins in Nordic Countries

    Importance Estimates of familial cancer risk from population-based studies are essential components of cancer risk prediction. Objective To estimate familial risk and heritability of cancer types in a large twin cohort. Design, Setting, and Participants Prospective study of 80 309 monozygotic and 123 382 same-sex dizygotic twin individuals (N = 203 691) within the population-based registers of Denmark, Finland, Norway, and Sweden. Twins were followed up a median of 32 years between 1943 and 2010. There were 50 990 individuals who died of any cause, and 3804 who emigrated and were lost to follow-up. Exposures Shared environmental and heritable risk factors among pairs of twins. Main Outcomes and Measures The main outcome was incident cancer. Time-to-event analyses were used to estimate familial risk (risk of cancer in an individual given a twin’s development of cancer) and heritability (proportion of variance in cancer risk due to interindividual genetic differences) with follow-up via cancer registries. Statistical models adjusted for age and follow-up time, and accounted for censoring and competing risk of death. Results A total of 27 156 incident cancers were diagnosed in 23 980 individuals, translating to a cumulative incidence of 32%. Cancer was diagnosed in both twins among 1383 monozygotic (2766 individuals) and 1933 dizygotic (2866 individuals) pairs. Of these, 38% of monozygotic and 26% of dizygotic pairs were diagnosed with the same cancer type. There was an excess cancer risk in twins whose co-twin was diagnosed with cancer, with estimated cumulative risks that were an absolute 5% (95% CI, 4%-6%) higher in dizygotic (37%; 95% CI, 36%-38%) and an absolute 14% (95% CI, 12%-16%) higher in monozygotic twins (46%; 95% CI, 44%-48%) whose twin also developed cancer compared with the cumulative risk in the overall cohort (32%). For most cancer types, there were significant familial risks and the cumulative risks were higher in monozygotic than dizygotic twins. Heritability of cancer overall was 33% (95% CI, 30%-37%). Significant heritability was observed for the cancer types of skin melanoma (58%; 95% CI, 43%-73%), prostate (57%; 95% CI, 51%-63%), nonmelanoma skin (43%; 95% CI, 26%-59%), ovary (39%; 95% CI, 23%-55%), kidney (38%; 95% CI, 21%-55%), breast (31%; 95% CI, 11%-51%), and corpus uteri (27%; 95% CI, 11%-43%). Conclusions and Relevance In this long-term follow-up study among Nordic twins, there was significant excess familial risk for cancer overall and for specific types of cancer, including prostate, melanoma, breast, ovary, and uterus. This information about hereditary risks of cancers may be helpful in patient education and cancer risk counseling.

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