医生的腺瘤检出率可预测间期结直肠癌风险

奥兰多——据消化疾病周(DDW)上报告的一项大型观察性研究，医生在结肠镜检过程中对腺瘤的检出率是其患者在阴性结肠镜检后发生结直肠癌的一项独立危险因素。医生的腺瘤检出率每降低1%，结直肠癌风险就增加约3%，结直肠癌病死风险就增加约4%。这些结果提示腺瘤检出率（医生检出至少1枚腺瘤的结肠镜筛查所占的比例）可能是一个有意义的质量评测指标。

Douglas Corley医生

由加州奥克兰凯撒医疗集团研究部的Douglas Corley医生及其合作者进行的这项研究所纳入的患者年龄≥50岁，已参加凯撒医疗集团北加州健康计划至少2年，并曾在1998~2010年间因任何适应证接受结肠镜检得出阴性结果。结肠镜检均由有经验(做过300余例结肠镜检并且在研究期内进行了75例以上筛查的内镜医生)的内镜医生进行操作。研究者对患者随访了10年或直至再进行1次阴性结肠镜检，健康计划会员资格终止，或诊断为结直肠癌，或是到2011年1月31日，以先到者为准。

研究中涉及314,872例结肠镜检，其中8,708例检出结直肠癌，在这部分患者中，有712例发生间期结直肠癌，即在指定的结肠镜检后至少6个月检查诊断出癌症。大多数（60%）间期癌症发生在近端。总体上，有34%为晚期癌症，20%左右导致直结肠癌相关死亡；1/3左右在间期早期被诊断出，即6个月至3年间。余下2/3在初次结肠镜筛检阴性后3~10年确立诊断。医生的腺瘤检出率为7%~52%不等，与既往文献中的报道一致。医生腺瘤检出率的五分位数与随后患者发生结直肠癌的风险间存在线性相关，但没有阈值效应。在校正结肠镜检适应证和患者年龄、性别、种族、结直肠癌家族史以及Charlson合并症评分等因素后，医生腺瘤检出率在第一、二五分位数的患者的风险比在最高五分位数者高出大约80%~90%。晚期结直肠癌的情况与之相近，不过相关性更强：医生腺瘤检出率在最低两个五分位数的患者的风险比在最高五分位数者高2倍以上。结直肠癌死亡风险的关系模式也同样如此：医生处于第一和第二五分位数的患者结直肠癌死亡风险比处于最高五分位数者增加2.5倍，风险不因患者状态或癌症位置而异。

Corley医生收到了由辉瑞制药提供的基金或研究赞助。

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By: SHARON WORCESTER, Internal Medicine News Digital Network

ORLANDO – The rate at which physicians detect adenomas during colonoscopy is an independent risk factor for their patients’ risk of developing colorectal cancer following a negative colonoscopy, according to findings from a large observational study.

Physicians with low rates of adenoma detection during screening colonoscopies were more likely to have patients who developed interval colorectal cancers. For every 1% decline in the physician adenoma detection rate, colorectal cancer risk increased by about 3%, and the risk of death related to colorectal cancer increased by about 4%, Dr. Douglas A. Corley reported at the annual Digestive Disease Week.

The findings suggest that adenoma detection rates – the proportion of screening colonoscopies in which a physician detects at least one adenoma – could be a useful quality metric, he said.

The findings were noted in a study of 314,872 colonoscopy exams in which 8,708 colorectal cancers were detected. Interval colorectal cancers – cancers diagnosed at examinations that took place at least 6 months after the index colonoscopy – were seen in 712 patients, said Dr. Corley, of the Kaiser Permanente Division of Research, Oakland, Calif.

Most (60%) interval cancers were proximal. In total, 34% were advanced cancers, and about 20% led to colorectal cancer–related deaths. About one-third were diagnosed in the early interval period, between 6 months and 3 years. The remaining two-thirds were diagnosed 3-10 years after an initial negative screening colonoscopy, Dr. Corley said.

Physician adenoma detection rates ranged from 7% to 52%, which are rates consistent with prior reports in the literature. There was a linear association across five quintiles of physician adenoma detection rates and subsequent patient colorectal cancer risk. "There’s no threshold effect above which increases in adenoma detection rate were without benefit," Dr. Corley said.

After adjusting for colonoscopy indication and patient age, sex, race/ethnicity, family history of colorectal cancer, and Charlson comorbidity score, the risk was about 80%-90% higher among patients of physicians whose adenoma detection rates were in the first or second quintile, as compared with patients of physicians with detection rates in the highest quintile.

A similar pattern was seen for advanced colorectal cancers, and the correlation was even stronger. The risk was increased more than twofold among patients of physicians in the bottom two quintiles of adenoma detection rates, compared with patients whose physicians were in the top quintile, he said.

Risk of death from colorectal cancer followed a similar pattern. Patients of physicians in the first and second quintiles had more than a 2.5-fold increased risk of colorectal cancer death compared with patients of physicians in the top quintile. Risk did not differ by patient status or by cancer location, Dr. Corley said.

Patients included in the study were aged 50 years or older, had been members of the Kaiser Permanente Northern California health plan for at least 2 years, and had a negative colonoscopy for any indication between 1998 and 2010. Only those colonoscopies performed by experienced endoscopists – those who had performed more than 300 colonoscopies and more than 75 screening exams during the study period – were included in the study.

Patients were followed for 10 years or until another negative colonoscopy was performed, health plan membership was terminated, a diagnosis of colorectal cancer was made, or Jan. 31, 2011 – whichever came first.

Dr. Corley has received grant or research support from Pfizer Pharmaceuticals.