GASTROENTEROLOGY：结直肠癌患者的无症状同胞应接受筛查

  香港中文大学威尔士亲王医院的Siew C. Ng博士及其同事报告称，与中国健康成人的同胞相比，中国结直肠癌患者的无症状兄弟姐妹发生晚期结直肠肿瘤的风险增加2倍，发生任何结直肠腺瘤的风险增加1倍。这项研究发表在《胃肠病学》杂志3月刊上(doi:10.1053/j.gastro.2012.11.011)。

　　Ng博士表示，鉴于上述结果，对这一高危人群有必要进行结直肠筛查，并切除筛查发现的任何癌前病变。

　　现行指南建议对结直肠癌患者的近亲属较早、较频繁地进行筛查，但以前并不清楚这样的筛查可产生怎样的成效。Ng博士及其同事对比了结直肠癌患者的同胞和结直肠筛查结果为阴性者的同胞的晚期肿瘤患病率。“选择这样的对照组可以避免家族史带来的偏倚，并且消除后天或环境因素的影响。”

　　10年期间共有374名结直肠癌患者同胞(年龄40~70岁，平均53岁)参加该研究，对照组招募了374名年龄、性别匹配的健康人同胞。两组受试者的肠道准备质量相似。所有筛查均采用常规白光结肠镜，在静脉内注射咪达唑仑和哌替啶清醒麻醉的情况下实施检查。3名参加研究的内镜医生均有丰富经验，且有可比的腺瘤检出率。

　　主要结局为晚期肿瘤(定义为直径≥10 mm、有高级别发育异常或绒毛状/管状组织学特性的癌症或腺瘤)患病率。结果显示，结直肠癌患者同胞的患病率(7.5%)接近健康对照者同胞(2.9%)的3倍，比值比(OR)为3.07。

　　有6名结直肠癌患者同胞被检出腺癌，而对照者中无1例检出腺癌。前者中包括Ⅰ期、Ⅱ期和Ⅲ期癌症各2例。结直肠癌患者同胞的大腺瘤患病率(5.9%)也接近对照者(2.1%)的3倍。前者的小腺瘤患病率(31%)约为后者(18.2%)的2倍。

　　当根据病变部位对数据进行分析时，研究者发现结直肠癌患者同胞的各种腺瘤患病率均高于对照者：远端腺瘤(13.1% vs. 8.3%)、近端腺瘤(12.0% vs. 6.2%)、同时性腺瘤(5.9% vs. 2.7%)。两组的增生性息肉患病率具有可比性(27.3% vs. 21.4%)。

　　当根据受试者年龄进行分析时，研究者发现各个年龄段的结直肠癌患者同胞，结直肠腺瘤的患病率均高于对照者：＜50岁(21.0% vs. 9.8%)、50~60岁(34.4% vs. 23.9%)或＞60岁(41.0% vs. 20.5%)。

　　在2项敏感性分析中，上述结果仍保持鲁棒性。

　　研究者还注意到，假如结直肠癌患者的病灶位于远端结肠而非近端结肠，则其同胞被检出晚期腺瘤的风险更高；假如结直肠癌患者为女性而非男性，则其同胞也有较高的晚期腺瘤风险。不过，由于这些亚组的受试者数量较小，因此对于上述结果需要谨慎解读。

Increased Risk of Advanced Neoplasms Among Asymptomatic Siblings of Patients With Colorectal Cancer 

Background & Aims

Colorectal cancer (CRC) is the second-most common cancer in Hong Kong. Relatives of patients with CRC have an increased risk of colorectal neoplasm. We assessed the prevalence of advanced neoplasms among asymptomatic siblings of patients with CRC.

Methods

Patients with CRC were identified from the Prince of Wales Hospital CRC Surgery Registry from 2001 to 2011. Colonoscopies were performed for 374 siblings of patients (age, 52.6 ± 7.4 y) and 374 age- and sex-matched siblings of healthy subjects who had normal colonoscopies and did not have a family history of CRC (controls, 52.7 ± 7.4 y). We identified individuals with advanced neoplasms (defined as cancers or adenomas of at least 10 mm in diameter, high-grade dysplasia, with villous or tubulovillous characteristics).

Results

The prevalence of advanced neoplasms was 7.5% among siblings of patients and 2.9% among controls (matched odds ratio [mOR], 3.07; 95% confidence interval [CI], 1.5–6.3; P = .002). The prevalence of adenomas larger than 10 mm was higher among siblings of patients than in controls (5.9% vs 2.1%; mOR, 3.34; 95% CI, 1.45–7.66; P = .004), as was the presence of colorectal adenomas (31.0% vs 18.2%; mOR, 2.19; 95% CI, 1.52–3.17; P < .001). Six cancers were detected among siblings of patients; no cancers were detected in controls. The prevalence of advanced neoplasms among siblings of patients was higher when their index case was female (mOR, 4.95; 95% CI, 1.81–13.55) and had distally located CRC (mOR, 3.10; 95% CI, 1.34–7.14).

Conclusions

In Hong Kong, siblings of patients with CRC have a higher prevalence of advanced neoplasms, including CRC, than siblings of healthy individuals. Screening is indicated in this high-risk population. ClinicalTrials.gov number: NCT00164944.