Clinicopathological and biological features of DNA tetraploid colorectal cancers

Most studies of colorectal cancers focus on a comparison of DNA diploid to non-diploid tumors consisting of tetraploid and aneuploid tumors. Tetraploid tumors alone have not been well studied. In the present study, clinicopathological and biological features of tetraploid colorectal cancers in contrast to those of diploid and aneuploid ones were investigated.

DNA ploidy in 278 primary colorectal adenocarcinomas was determined by flow cytometry.

Among 278 cases, 8% of the cases were tetraploidy, 44% were aneuploidy, and 48% were diploidy. Compared to diploid tumors, tetraploid tumors were more frequent in advanced stage, high index of S-phase fraction and apoptosis, higher expression of Cox-2, c-erbB-2 and heat shock protein, but had decreased inflammatory infiltration (P<0.05). Compared to aneuploid tumors, tetraploid tumors had a high frequency of microsatellite instability, high expression of Cox-2 and heat shock protein (P<0.05). Unlike tetraploid tumors, aneuploid tumors had increased p53 expression but did not have microsatellite instability (P<0.05). Tetraploidy and aneploidy predicted a worse prognosis in the subgroups of stages A-C, proximal colon, p53 negative expression and higher S-phase fraction (P<0.05).

DNA tetraploid tumors seem, to some extent, to exhibit distinct characteristics of clinicopathology and biology compared with aneuploid or diploid colorectal cancers.