Quantitative analysis of numerical chromosome aberrations in various morphological types of colorectal carcinomas

Comparison of the expression of ABH/Lewis-related antigens in polypoid and non-polypoid growth types of colorectal carcinoma

BACKGROUND AND AIMS

Colorectal tumors can be classified based on their growth pattern into the polypoid growth-type (PG-type) and non-polypoid growth-type (NPG-type). To ascertain whether there is any relationship between the expression of particular blood group-related antigens (A, B, H, Lewis (Le)a, sialyl Le(a), Le(x), sialyl Le(x)) in a colorectal tumor, and a tumor having polypoid or non-polypoid growth, we examined 78 PG-type and NPG-type colorectal cancers.

METHODS

Fourteen PG-type and 64 NPG-type colorectal carcinomas were subjected to immunohistochemical analyses by using monoclonal antibodies against A, B, H, Le(a), sialyl Le(a), Le(x) and sialyl Le(x).

RESULTS

The patients with NPG-type carcinomas had a significantly younger age of onset, significantly smaller maximal tumor diameter, significantly higher rate of lymph node metastasis and significantly worse prognosis than those with PG-type carcinomas. Among the 32 tumors of patients with blood type A or AB, isoantigen A was expressed in a significantly larger percentage of NPG-type carcinomas than PG-type carcinomas (95.8 vs 62.5%, respectively; P=0.014). Among all 78 tumors, sialyl Le(x) antigen was expressed in a significantly larger percentage of NPG-type than PG-type carcinomas (90.6 vs 64.3%, respectively; P=0.010). Multivariate analysis using the logistic regression model revealed that isoantigen A and sialyl Le(x) expression were independent predictive risk factors for the development of NPG-type colorectal carcinoma.

CONCLUSIONS

These data suggest that the expression of isoantigen A and sialyl Le(x) in a colorectal carcinoma partially determines whether the tumor will have polypoid or non-polypoid growth.

Increased expression of sialyl Le(x) antigen in non-polypoid growth type of colorectal carcinoma

Colorectal carcinoma can be morphologically divided into two different categories, namely polypoid growth (PG-type) and non-polypoid growth (NPG-type). To ascertain whether the expression of sialyl Le(x) antigen correlates with biologically and clinically important differences, an immunohistochemical assay was performed in 30 PG-type and 119 NPG-type cancers. In contrast to PG-type, the characteristics of the NPG-type include (1) an increased expression of sialyl Le(x); (2) a high rate of lymph node metastasis; (3) a high proportion of moderately differentiated adenocarcinoma cells; (4) young age of onset. It is concluded that differences in sialyl Le(x) expression between the PG-type and NPG-type cancers may be at least partly responsible for different tumor progression behavior.

Different expressions of sialyl Tn antigen between polypoid and flat-type early colorectal cancers

PURPOSE

Sialyl Tn (STn) antigen is a cancer-associated carbohydrate antigen expressed in cancers of the digestive tract. We compared the proportion of specimens of flat-type colorectal cancers expressing STn with that of polypoid cancers, by examining the immunohistochemical reactivity of STn in various morphologic types of early and advanced colorectal cancers.

METHODS

A total of 111 biopsies from the colorectal area were examined for STn expression, including 11 adenomas, 58 early cancers, and 42 advanced cancers. Each section was stained immunohistochemically for STn antigen. In each section, we examined STn expression in the cancer area, adjacent mucosa, and normal epithelium.

RESULTS

STn expression was detected in 90.9 percent of adenomas, 36.2 percent of early cancers (T1), 64.3 percent of advanced cancers (>T1), and 52 percent of mucosa adjacent to cancer. The morphology of cancer tissue did not influence the number of specimens exhibiting STn antigen expression in mucosa adjacent to cancer cells. STn antigen was rarely expressed in flat or depressed-type early cancers (T1; 7.1 percent), and the expression was higher in moderately than in well-differentiated adenocarcinomas. In advanced cancers (>T1), a similar proportion of protruding and small ulcerative cancers expressed STn.

CONCLUSION

Our results suggest that the low expression of STn antigen in flat-type cancers may be the result of different mechanisms of cellular transformation during carcinogenesis from the usual adenoma-carcinoma sequence in colorectal neoplasms.

Aneusomy of chromosome 18 is associated with the development of colorectal carcinoma

Specific loss of heterozygosity of chromosome 18 has been observed frequently in advanced colorectal carcinoma and is closely associated with its development. We investigated the prevalence of numerical aberrations of chromosome 18 in 44 specimens of colorectal carcinomas, using fluorescence in situ hybridization. We also examined the relationship between aneusomy of chromosome 18 and the clinicopathological features of these tumors. Aneusomy of the specimens (monosomy and polysomy) was determined when the same aneusomic population was detected in more than 15% of the nuclei. The frequency of monosomy and polysomy of chromosome 18 in colorectal carcinomas was 43% (19/44) and 29% (12/44), respectively. The prevalence of monosomy and polysomy 18 was significantly higher in cancers with invasion exceeding category T2 compared with T1 (P < 0.01), and with tumor size exceeding 20 mm in diameter compared with tumors less than 20 mm (P < 0.05). However, the prevalence of aneusomy 18 was not associated with other clinico-pathological features. The mean survival period and the 5-year survival rate after operation in patients with aneusomy 18 was not different from findings for those with disomy 18. Our results indicate that aneusomy of chromosome 18 is associated with the development of colorectal carcinoma; however, it is not a useful indicator of postoperative prognosis.