Approximately 35% of patients with colorectal cancer (CRC) have a family history of the disease attributed to genetic factors, common exposures, or both. Some families with a history of CRC carry genetic variants that cause CRC with high or moderate penetrance, but these account for only 5% to 10% of CRC cases. Most families with a history of CRC and/or adenomas do not carry genetic variants associated with cancer syndromes; this is called common familial CRC. Our understanding of familial predisposition to CRC and cancer syndromes has increased rapidly due to advances in next-generation sequencing technologies. As a result, there has been a shift from genetic testing for specific inherited cancer syndromes based on clinical criteria alone, to simultaneous testing of multiple genes for cancer-associated variants. We summarize current knowledge of common familial CRC, provide an update on syndromes associated with CRC (including the nonpolyposis and polyposis types), and review current recommendations for CRC screening and surveillance. We also provide an approach to genetic evaluation and testing in clinical practice. Determination of CRC risk based on family cancer history and results of genetic testing can provide a personalized approach to cancer screening and prevention, with optimal use of colonoscopy to effectively decrease CRC incidence and mortality.

中文翻译：

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利用家族病史和基因检测来确定结直肠癌的风险。

大约35％的结肠直肠癌（CRC）患者有家族病史，原因是遗传因素，常见暴露或两者兼而有之。一些具有CRC病史的家庭携带的遗传变异会导致CRC高或中度外显率，但这些仅占CRC病例的5％至10％。大多数有CRC和/或腺瘤病史的家庭不携带与癌症综合症有关的遗传变异。这称为普通家族性CRC。由于下一代测序技术的进步，我们对CRC和癌症综合症的家族易感性的了解迅速增加。结果，已经从仅基于临床标准对特定遗传性癌症综合征进行基因检测，转变为同时检测与癌症相关的变异体的多个基因。我们总结了目前常见的家族性CRC知识，提供了与CRC相关的综合症的最新信息（包括非息肉病和息肉病类型），并回顾了有关CRC筛查和监测的当前建议。我们还提供一种在临床实践中进行基因评估和测试的方法。根据家族癌症史和基因检测结果确定CRC风险，可以提供个性化的癌症筛查和预防方法，并且可以最佳地使用结肠镜检查来有效降低CRC的发生率和死亡率。