Fluorescence in situ hybridization analysis of c-myc amplification in stage TNM prostate cancer in Japanese patients.

OBJECTIVE

Genetic aberration such as the amplification of c-myc has been commonly found in advanced prostate cancer. The aim of this study was to elucidate chromosome 8 alteration, including a gain and amplification of 8q24 (c-myc gene), related to the progression and survival in advanced (Stage C) prostate cancer.

MATERIALS AND METHODS

We used dual-probe fluorescence in situ hybridization with a centromere-specific probe for chromosome 8 (8cen), and with a region-specific probe for c-myc (8q24) to evaluate genetic changes in tumor samples from 50 patients who had undergone radical retropubic prostatectomy from 1986 to 2001.

RESULTS

We classified the 8cen and c-myc copy numbers as normal, gain and amplification. The carcinoma foci with extra copies of c-myc, which was defined in 35 cases (70%), were divided into two groups: (a) a simple gain of the whole chromosome 8 (no increase in the c-myc copy number relative to the chromosome 8 centromere), which was identified in 15 cases (30%); and (b) a substantial amplification of c-myc (additional increases [AI] in the c-myc copy number relative to the chromosome 8 centromere), which was detected in 20 cases (40%). AI-c-myc was strongly associated with higher histopathological grades and Gleason's scores (P = 0.0330, 0.0190, respectively). Patients with the AI-c-myc had earlier disease progression (P = 0.0029) and earlier cancer death (P = 0.0087) than did patients with normal patterns.

CONCLUSION

Identification of an AI-c-myc may serve as a potential marker of prostate cancer progression.