OBJECTIVETo investigate the clinicopathological features and prognosis of colorectal synchronous multiple primary cancer(SMPC).

METHODSFrom January 2008 to June 2011, 51 patients diagnosed with colorectal SMPC underwent surgery at Department of General Surgery of Peking University First Hospital. Their clinicopathological features, diagnosis, treatment and prognosis were summarized and analyzed. SMPC was diagnosed according to the following criteria: each tumor must have a definite pathologic picture of malignancy; metastasis or recurrence from another colorectal cancer was excluded; tumors must be distinctly separated by at least 5 cm of all intact bowel wall from each other; SMPC has abnormal cells between tumor and normal mucosa and abnormal gland of transitional zone; each cancer is infiltrating carcinoma except the carcinoma in situ; all the cancers are detected at the same time or within 6 months. Multiple primary colorectal cancer originated from familial colonic polyposis or ulcerative colitis was excluded.

RESULTSThese 51 colorectal SMPC patients accounted for 3.5% of 1 452 colorectal cancer patients in the same period at our hospital, with 32 males and 19 females, and mean age of (63±13)(29 to 82) years. Of 51 cases, 46(90.2%) had 2 original carcinoma, 3(5.9%) had 3 original carcinoma and 2(3.9%) had 4 carcinoma; 23(45.1%) complicated with colon polyps, 4(7.8%) complicated with malignancy outside the colorectum. In TNM staging, 7(13.7%), 15(29.4%), 24(47.1%) and 5(9.8%) patients were stage I(, II(, III( and IIII( respectively. Among 51 patients undergoing surgery by different procedures, 16 were subtotal colon resection, 8 were extended right colon resection, 5 were extended left hemicolon resection, 8 were right hemicolon resection plus Dixon procedure, 10 were Dixon, and 4 were right hemicolon resection plus sigmoid colon resection. Adjuvant chemotherapy and support treatment were given according to the condition after operation. A total of 105 tumors were found, including 25(23.8%) tumors in sigmoid colon, 24(22.9%) in rectum, 22(21.0%) in ascending colon and 4 in organs outside the colorectum. Tubular adenocarcinoma (86/105, 81.9%) was the main pathological type in these colorectal SMPC patients. During the follow-up of median 43.5 months, 10 cases presented local recurrence and 6 cases had liver metastasis. Multivariable analysis showed that ≤65 years old (OR=22.757, 95%CI: 1.562-331.543, P=0.002),undifferentiated carcinoma or mucous adenocarcinoma (OR=27.174, 95%CI: 2.834-260.512, P=0.004), stage III(-IIII( (OR=29.626, 95%CI: 3.216-272.884, P=0.003) were independent risk factors of postoperative 5-year recurrence and metastasis, but the number of SMPC lesions and the surgical method were not associated with postoperative 5-year recurrence and metastasis (P=0.564, P=0.513). The 3-year and 5-year survival rates of colorectal SMPC patients were 76.5% and 64.7%.

CONCLUSIONTwo-original carcinoma is the most common in colorectal SMPC patients, which mainly distributes in sigmoid colon and rectum. Postoperative monitoring should be strengthened for those patients with younger age, poor pathological types and advanced staging to prevent recurrence and metastasis.