Tumori. 1995 May-Jun;81(3):157-63. doi: 10.1177/030089169508100301.
The Multicenter Study of Colorectal Adenomas (SMAC) is a retrospective-prospective cohort study involving four Gastrointestinal Endoscopy Units in Italy. The main aim of the study is to evaluate the relationship between clinical and pathologic information at index colonoscopy and subsequent incidence of adenoma and colorectal carcinoma. We report the rationale, objectives and methods of the study, including patient characteristics at initial presentation.
All patients were consecutively identified from the endoscopy registries of the four Centres from January 1, 1985 to December 31, 1992. Inclusion criteria were: age 18-69 years, endoscopy performed with adequate toilette at least up to the rectosigmoid junction, and removal of all detectable polyps. Exclusion criteria were: familial adenomatous polyposis, inflammatory bowel diseases, adenocarcinoma in adenoma with infiltrated margins, previous invasive cancer at any site, colon resection and geographic inaccessibility.
Out of 20,071 patients who underwent endoscopy at the four Centres, 11,959 fulfilled the eligibility criteria (5,892 males and 6,067 females, mean age = 51.1 +/- 11.6 years). The main reasons for exclusion were age (n = 4,020) and previous or present colorectal cancer (n = 2,389). Symptoms were the most common reason for referral (72.3%), while post-polypectomy follow-up and positive fecal occult blood accounted for most of the remaining cases. A pancolonoscopy was performed in 3,088 patients (25.8%), while a left-sided endoscopy was performed in 7,887 (66%). A total number of 4,810 polyps were removed from 2,699 patients (2,994 adenomas, 1,580 hyperplastic polyps and 236 polyps lost after resection). A significant association (p < 0.001) between age and the endoscopic findings was observed. The subjects without polyps (n = 9,198) had the lowest age (mean = 49.9; 95%CL = 49.6-50.1) followed by the patients with hyperplastic polyps (n = 661; mean age = 52.3; 95%CL = 51.5-53.1), and the patients with adenomas (n = 1,732; mean age = 56.2; 95%CL = 55.8-56.6), and the patients with hyperplastic polyps and adenomas (n = 306; mean age = 57.2; 95%CL = 56.3-58.2). Polyps were diagnosed more frequently in males than in females (28.6% versus 17.0%; p < 0.0001).
This study provides some insights in the natural history of colorectal cancer and stresses the need to develop adequate strategies in the follow-up of subjects after either positive or negative colonoscopy.
结直肠腺瘤多中心研究（SMAC）是一项回顾性-前瞻性队列研究，涉及意大利的四个胃肠内镜检查单位。该研究的主要目的是评估首次结肠镜检查时的临床和病理信息与随后腺瘤和结直肠癌发病率之间的关系。我们报告该研究的基本原理、目标和方法，包括初次就诊时的患者特征。
从1985年1月1日至1992年12月31日，在四个中心的内镜检查登记处连续识别所有患者。纳入标准为：年龄18 - 69岁，至少在直肠乙状结肠交界处进行充分肠道准备的内镜检查，以及切除所有可检测到的息肉。排除标准为：家族性腺瘤性息肉病、炎症性肠病、边缘浸润性腺瘤中的腺癌、既往任何部位的浸润性癌、结肠切除术以及地理位置不便。
在四个中心接受内镜检查的20,071名患者中，11,959名符合入选标准（男性5,892名，女性6,067名，平均年龄 = 51.1 ± 11.6岁）。排除的主要原因是年龄（n = 4,020）和既往或当前的结直肠癌（n = 2,389）。症状是转诊的最常见原因（72.3%），而息肉切除术后随访和粪便潜血阳性占其余病例的大部分。3,088名患者（25.8%）进行了全结肠镜检查，7,887名患者（66%）进行了左侧内镜检查。共从2,699名患者中切除了4,810个息肉（2,994个腺瘤、1,580个增生性息肉和236个切除后丢失的息肉）。观察到年龄与内镜检查结果之间存在显著关联（p < 0.001）。无息肉的受试者（n = 9,198）年龄最小（平均 = 49.9；95%置信区间 = 49.6 - 50.1），其次是增生性息肉患者（n = 661；平均年龄 = 52.3；95%置信区间 = 51.5 - 53.1）、腺瘤患者（n = 1,732；平均年龄 = 56.2；95%置信区间 = 55.8 - 56.6）以及增生性息肉和腺瘤患者（n = 306；平均年龄 = 57.2；95%置信区间 = 56.3 - 58.2）。息肉在男性中的诊断频率高于女性（28.6%对17.0%；p < 0.0001）。
本研究为结直肠癌的自然史提供了一些见解，并强调在结肠镜检查结果为阳性或阴性的受试者随访中制定适当策略的必要性。
