Fish detected p53 deletion and N-MYC amplification in colorectal cancer

Data about p53 condition in sporadic colorectal cancer and its impact on clinical features is controversial, and studies regarding N-myc gene in colorectal cancer are limited in number. Our aim was to determine the frequency of p53 deletion and N-myc amplification by fluorescence in situ hybridization method in colorectal cancer and their relationship with clinical parameters.

The study was prospectively derived from 40 patients who were diagnosed as having colorectal cancer (Dukes' stages: 11 B, 18 C, 11 D) and went to surgery. Fresh tumor samples from all patients and adjacent normal tissue from 16 patients as control specimens were obtained. Locus specific fluorescence in situ hybridization probes was used for p53 and N-myc gene. For each sample, hundred interphase nuclei were analyzed based on their fluorescence phenotype.

Both p53 allelic loss and N-myc amplification were found in 21 cancer tissues, while p53 allelic loss was not observed in any of control tissue, and N-myc amplification only in 1 (p<0.001, p<0.01). Mutations were significantly related with metastasis.

Our study indicates that p53 and N-myc mutations are frequently found in tumor tissue of colorectal cancer and both gene alterations are correlated with the more aggressive tumor phenotype.