[Molecular classification of colorectal carcinoma based on integration of gene expression profile and copy number variation].

OBJECTIVE: To classify colorectal carcinoma (CRC) by TNM staging integrated with the gene expression profile and copy number variation (CNV). METHODS: Profile data of gene expression and CNV of CRC were downloaded from public database and processed with batch bias adjustment, quartile normalization, missing value estimation and feature filtration. The processed profiles of mRNA and CNV were introduced into the codes of Bayesian consensus clustering (BCC) method and were used to calculate the subclasses of CRC. With the follow-up information of disease free survival of CRC patients, the prognostic values of the subclasses was investigated and the software of function enrichment analysis was employed to discover the major pathway signaling to each interesting subclass. All statistic analyses were performed under R-3.0.1 environment or by using SPSS 16.0 software. RESULTS: Profile data of gene expression and corresponding CNV from 335 CRC patients with TNM stage Ⅱ-Ⅲ and followed-up information were obtained. After feature filtering, the profiles contained 1578 probes of mRNA and 345 location of CNV. Four CRC subclasses were identified by the integrative analysis with BCC, and the concordances of BCC subclasses and each of gene-based subclasses (Cramer's V=0.49), CNV-based subclasses (Cramer's V=0.51) and Marisa's subclasses (Cramer's V=0.32) were statistically significant (Ps<0.001). Among BCC subclasses, BCC-I had a favorable prognosis, while BCC-Ⅳ had more unfavorable prognosis. The differences of prognosis were significant among BCC-I, BCC-(Ⅱ+Ⅲ) and BCC-Ⅳ with an overall log-rank P<0.001. The top enriched function was DNA damage and repair signaling when BCC-I compared to BCC-Ⅳ, and the new subgroups classified by the genes associated with enriched signaling had the better prognostic value than BCC subclasses but both of them were significantly correlated (Cramer's V=0.39, P<0.001). CONCLUSION: BCC method is effective to integrate multi-type genomic data for molecular classification of colorectal carcinoma, and the BCC-Ⅳ subclass has poor prognosis, which may be associated with the decreased repairing function of DNA damage.

[Gene methylation in stool for the screening of colorectal cancer and pre-malignant lesions].

OBJECTIVE: To evaluate association between DNA methylation of MAL, CDKN2A, and MGMT in stool and development of colorectal cancer, and to evaluate the screening value of these biomarkers in colorectal cancer and pre-malignant lesions. METHODS: Morning stool specimens were collected from 69 patients with colorectal cancer, 24 with colon adenoma, 19 with hyperplastic polyps, and 26 healthy controls. DNA was extracted and treated with bisulfite. Methylation-specific PCR(MSP) was performed for methylation analysis of MAL, CDKN2A and MGMT in DNA samples. Associations between clinicopathological features and gene methylation were analyzed. The sensitivity of diagnosis by combining three methylation markers was compared with fecal occult blood test(FOBT). RESULTS: The methylation frequencies of MAL, CDKN2A and MGMT were 78.3%, 52.5% and 55.1% in colorectal cancer, 58.3%, 41.7% and 37.5% in colon adenomas, 26.3%, 15.8% and 10.5% in hyperplastic polyps, and 3.8%, 0 and 3.8% in healthy controls, respectively. Significant differences in three genes were found between colorectal cancer and hyperplastic polyp, colorectal cancer and healthy control, colon adenoma and hyperplastic polyp, colon adenoma and healthy control(all P<0.05). The diagnostic sensitivity by combining three methylation markers was 92.8% in colorectal cancer, 70.8% in colon adenomas, significantly higher than FOBT examination (29.0% in colorectal cancer and 25.0% in colon adenomas, all P<0.05). No significant associations existed between three genes methylation of the three genes and clinical characteristic including sex, age, tumor location, lymph node metastases and TNM stage (all P>0.05). CONCLUSION: DNA methylations levels of MAL, CDKN2A, and MGMT in stools are significantly higher in colorectal cancer and colon adenoma, which may serve as an noninvasive approach for the screening of colorectal cancer and pre-malignant lesions.

Could tumor characteristics identified by colonoscopy predict the locally advanced rectal carcinoma?

BACKGROUND: Neoadjuvant chemoradiation is now considered the standard care for locally advanced rectal carcinoma (T3-4 or/and N1-2 lesions), but the accuracy of staging examinations including endorectal ultrasonography (ERUS) and MRI is far from excellent. In addition, the above staging equipment or professionals who perform the examinations may not be available in some hospitals, while preoperative colonoscopy and biopsy are usually obtainable in most hospitals. The objective of the present study was to investigate the clinical and pathological characteristics of locally advanced rectal carcinoma and identify candidates for neoadjuvant chemoradiation. METHODS: This was a retrospective study. Patients who were treated for rectal cancer at Changhai Hospital from January 1999 to July 2008 were identified from our prospectively collected database. Statistical analysis was performed using SPSS Software System (version 15.0). The Mann-Whitney test, chi-square test and multivariate Logistic regression analysis were performed. RESULTS: A total of 1005 cases were included in this research, of which 761 cases were identified as locally advanced rectal carcinoma depending on postoperative TNM staging. The results of multivariate Logistic regression analysis indicated seven independent risk factors that could be used to predict a locally advanced rectal carcinoma independently: a high grade (including poor differentiation and undifferentiation) (OR: 3.856; 95% CI: 2.064 to 7.204; P = 0.000); large tumor size (OR: 2.455; 95% CI: 1.755 to 3.436; P = 0.000); elevated preoperative serum CEA level (OR: 1.823; 95% CI: 1.309 to 2.537; P = 0.000); non-polypoid tumor type (OR: 1.758; 95% CI: 1.273 to 2.427; P = 0.001); the absence of synchronous polyps (OR: 1.602; 95% CI: 1.103 to 2.327; P = 0.013); the absence of blood in stool (OR: 1.659; 95% CI: 1.049 to 2.624; P = 0.030); and a greater circumferential tumor extent (OR: 1.813; 95% CI: 1.055 to 3.113; P = 0.031). Based on these findings, a Logistic equation was established, the accuracy of which was 64% according to the information of the additional 50 cases. CONCLUSIONS: Some independent risk factors related with locally advanced rectal carcinoma were identified, based on which it is possible to establish a Logistic equation as a tool to predict candidates of neoadjuvant chemoradiation. Further research about optimization of the equation is warranted.

[Lymph node metastasis and its risk factors in T1-2 staging invasive rectal carcinoma].

OBJECTIVE: To investigate the lymph node metastasis and its risk factors in T1-2 staging invasive rectal carcinoma. METHODS: The data of 1116 patients with rectal cancer treated with total mesorectal excision (TME) technique from January 2000 to April 2009 was analyzed retrospectively. The clinicopathological factors analyzed included gender, age, primary symptom type, number of symptoms, duration of symptom, synchronous polyps, preoperative serum carcino-embryonic antigen level, preoperative serum CA19-9 level, the distance of tumor from the anal verge, tumor size, tumor morphological type, tumor circumferential extent, tumor differentiation and tumor T staging. Statistical analysis was performed by using Logistic regression analysis and Chi-square test. RESULTS: A total of 1116 patients were enrolled, and 358 cases (32.1%) were classified as with T1-2 staging tumor. Two cases (5.6%, 2/36) in patients with a T1 staging tumor were found with lymph node metastasis, and 75 cases (23.3%, 75/322) in patients with a T2 staging tumor, respectively. Compared with patients with T3-4 staging tumor, lymph node metastasis rate of the patients with T1-2 staging tumor was significantly lower [21.5% (77/358) vs. 51.6% (391/758), P < 0.05]. Only the tumor T staging was found as the independent risk factor for the lymph node metastasis in patients with T1-2 staging tumor on multivariate Logistic regression analysis (odds ratio: 5.162; 95%CI: 1.212 to 21.991; P = 0.026). CONCLUSIONS: A substantial proportion of T1-2 staging rectal cancers harbor metastatic lymph nodes and the clinicopathological features except for T staging fail to predict the lymph node metastasis. Further research is warranted to identify the risk factors and guide the clinical practice in patient with T1-2 staging tumor.

Patterns of lymph node metastasis are different in colon and rectal carcinomas.

AIM: To describe patterns of lymph node metastasis in invasive colon and rectal carcinomas. METHODS: Clinical data of 2340 patients with colorectal carcinoma (stage I to III) who received radical resection, was retrospectively reviewed. Of the 2340 patients, 1314 patients suffered from rectal carcinoma and 1026 from colon carcinoma. Patients with rectal cancer who received neoadjuvant chemoradiation therapy were excluded. Statistical analysis was performed using Mann-Whitney, χ(2) and Cochran's and Mantel-Haenszel tests (SPSS 15.0). A two-tailed P < 0.05 was considered statistically significant. RESULTS: Lymph node retrieval in the rectal carcinoma group was significantly lower than that in the colon carcinoma group (P < 0.001), while positive lymph node retrieval in the rectal carcinoma group was significantly higher than that in the colon carcinoma group (P < 0.001). The proportion of lymph node positive (N+) cases was higher (patients with one or more positive lymph nodes) in the rectal carcinoma group (P = 0.004). The number of N+ cases was compared at different T stages (T1-T4) to eliminate background bias and the results were confirmed (P < 0.001). In addition, the lymph node ratio (the ratio of number of positive lymph nodes over the number of lymph nodes examined) of stage III cases in the rectal carcinoma group was significantly higher than that in the colon carcinoma group (P < 0.001). CONCLUSION: Rectal carcinomas seem more prone to metastasize to the lymph nodes than colon carcinomas, which may be of potential clinical significance.

[Analysis on misdiagnosis of 271 patients with rectal cancer].

OBJECTIVE: To investigate the common reasons for the misdiagnosis of rectal cancer. METHODS: A retrospective study was performed in 568 cases of rectal cancer in the Changhai Hospital from January 2007 to December 2008. Age at diagnosis, gender distribution, symptom, delay in diagnosis, TNM stage, and grade of differentiation were recorded and analyzed. The importance of digital examination and colonoscopy were addressed. RESULTS: Two hundred and seventy-one(47.7%) out of 568 patients were misdiagnosed for iatrogenic reasons. Rectal cancer patients who presented hematochezia were more likely to be misdiagnosed. There were 110 cases of stage III(40.6%) and 68 cases of stage IV(12.5%) in patients who were misdiagnosed, which was significantly higher than those who were diagnosed correctly(P<0.05). Patients under 40 years old were more likely to be misdiagnosed, and their correct diagnosis was often delayed longer and the tumors were in more advanced stage as compared to the older groups(P<0.05). CONCLUSIONS: The misdiagnosis rate of rectal cancer is high. Tumor stage of patients misdiagnosed is significantly more advanced than those who are correctly diagnosed. Digital examination and colonoscopy should be emphasized, especially for patients under the age of 40.