Anatomic site distribution and clinic pathologic characteristics of colorectal cancer in young Chinese

Clinical characteristics of colorectal neoplasms: A retrospective analysis of 260 cases

AIM: To investigate the clinical characteristics of colorectal neoplasms so as to provide the basis for clinical diagnosis and treatment.

METHODS: The clinical data for 260 patients with primary colorectal neoplasms diagnosed surgically and pathologically in 2010 at our hospital were analyzed retrospectively. The clinical features for colorectal neoplasms and the association of smoking, drinking and past medical history with tumor progression were analyzed.

RESULTS: Male/female ratio was 1.24:1, and the average age was 61.73 ± 11.56 years. The incidences by tumor site ranked in descending order were the rectum, the sigmoid colon, the ascending, transverse and descending colons. Synchronized carcinomas of the colon and rectum were found in 8 cases. Approximately 64.23% of rectal neoplasms were located within 8 cm to the anus. The average length was significantly longer in male cases than in female cases (8.22 cm ±3.35 cm vs 7.08 cm ± 2.09 cm, t = 2.20, P = 0.03). Bloody stools was the main symptom of left-sided colonic and rectal neoplasms, while abdominal pain and abdominal distension were main symptoms of right-sided colonic neoplasms. The positive rate of fecal occult blood test (OBT) was 80.43%. The ratio of cases in Dukes stage A was 18.85%. Tumor differentiation degree was negatively correlated with age (r = -0.145, P = 0.019). The incidence rate of right-sided colonic neoplasms among cholecystectomy patients was higher than left-sided ones but the difference was not statistically significant (P > 0.05). The incidences of metastasis and infiltration among essential hypertension patients were lower (both P < 0.05).

CONCLUSION: Digital rectal examination (DRE) and OBT are two important methods for finding colorectal neoplasms. Bloody stools and abdominal pain, abdominal distension are the main symptoms of right- and left-sided colonic neoplasms, respectively. There is an increased trend in early diagnosis. Age, cholecystectomy and essential hypertension may relate to pathogenesis and development of colorectal neoplasms.

Analysis on clinicopathological characteristics and prognosis of 576 patients with primary colorectal cancer

AIM: To analyze the clinicopathological characteristics of primary colorectal cancer and explore the influencing factors on the prognosis of patients.

METHODS: The clinical data of 576 patients with colorectal cancer diagnosed by colonoscopy during the past five years in the second affiliated hospital of Sun Yat-Sen University were analyzed retrospectively.

RESULTS: The occurrence rate of colorectal cancer was not significantly different between patients of different ages. The frequency of abdominal pain (χ² = 7.20, P < 0.05), the proportion of mucinous adenocarcinoma (χ² = 43.71, P < 0.05) and the rate of lymph node metastasis (χ² = 4.47, P < 0.05) in adolescent group were significantly higher than those in the mid-aged and aged one. The number of thin individuals was markedly higher in the aged group than that in the adolescent and mid-aged group (χ² = 9.64, P < 0.05). High differentiation was also observed in the aged patients (χ² = 8.06, P < 0.05). The overall 5-year survival rate was 61.79% (43.64%, 87.16% and 53.79% in the adolescent, mid-aged, and aged patients, respectively). The prognosis of colorectal cancer was associated with the age, tumor cell differentiation, lymph node metastasis, Dukes stages and the radical operation.

CONCLUSION: The frequency of abdominal pain, the malignant degree and the proportion of lymph node metastasis are the highest in the young patients. Age and Dukes staging are the independent factors correlated with the prognosis.

Expression of HLA molecule in colorectal cancer tissue

AIM: To study the relationship between the expression of HLA class I and clinicopathological significance in colorectal cancers.

METHODS: Expression of HLA class I and associated proteins was studied by immunohistochemistry in colorectal cancer, histologically normal mucosa adjacent to cancer (<3 cm), and histologically normal mucosa distant from cancer. Several monoclonal antibodies (mAbs) were used in this study: HC10 and HCA2 reacted with the nonmorphic determinant of heavy chain of HLA class I antigen; L368 reacted with ₂ microglobulin; SY1 reacted with LMP2 antigen, and TO-5 reacted with calnexin.

RESULTS: In colorectal cancer tissues, the expression of HLA -A,B/C, ₂M, LMP2 and calnexin were reduced compared to that of both in histologically normal mucosa adjacent to cancer and histologically normal mucosa distant from cancer (P = 0.001).The expression of calnexin in cancer was also reduced compared to that of both in histologically normal mucosa adjacent to cancer and histologically normal mucosa distant from cancer (P = 0.004). The expression of HLA-B/C antigen in cancer was associated with diverse groups of pathological stage. With increase in Dukes staging of the cancer, the expression of HLA-B/C downregulated, in which that in Dukes A was higher than that in Dukes D (P = 0.0262).

CONCLUSION: The expression of HLA class I and associated protein is downregulated in the colorectal cancer tissue. It may be one important mechanism by which colorectal cancer cell escapes immune surveillance.

Effects of tumor suppressor gene NGX6 on growth of human colon cancer cell line HT-29

AIM: NGX6 is a novel tumor suppressor gene candidate, and the expression of NGX6 decreased in colon cancer specimen, which suggested that the down-regulation of NGX6 was closely related to tumorigenesis of colon cancer. This study was designed to explore effects of NGX6 on the cytobiological characteristics of human colon cancer cell line HT-29 and to elucidate the role of NGX6 in the colon cancer.

METHODS: The mammal expression vector of pcDNA3.1(+)/NGX6 was transfected into human colon cancer cell line HT-29 cells by liposome.The integration of the exogenous vector DNA and the expression of NGX6 were detected by dot blot and RT-PCR. Finally, the cytobiological characteristics of positive clone were analyzed by growth curves of cells, MTT, soft agar assay, FCM and xenograft.

RESULTS: pcDNA3.1(+)/NGX6/HT-29 cells grew slower than pcDNA3.1(+)/HT-29 and HT-29 cells (P < 0.05), and the PDT of pcDNA3.1(+)/NGX6/HT-29 cell was 34.5 hours, which was significantly longer than that of pcDNA3.1(+)/HT-29 cells (27.1 h) and HT-29 cells (23.0 h). FCM data showed that the overexpression of NGX6 blocked the progression of G1→S phase in cell cycle, and it also presented decreased clonogenicity in soft agar assay and tumor formation in nude mice.

CONCLUSION: The re-expression of NGX6 can reverse the malignant phenotype of human colon cancer cell line HT-29. Therefore, NGX6 gene may be a good candidate of tumor suppressor gene associated with colon cancer.