del(1)(q12) in adenocarcinomas of the prostate

Deletion (1)(q12) and double minutes in a metastatic adenocarcinoma of the prostate

Cytogenetic analysis after short-term cultures were performed on an invasive and moderately-differentiated prostatic adenocarcinoma. The results showed a normal male chromosomal complement in most metaphases examined. Furthermore, several abnormalities were found, including del(1)(q12), double minute and ring chromosomes, acentric fragments, triradial figures, and near-tetraploid cells.

Chromosomal basis of adenocarcinoma of the prostate

Prostate cancer is the most frequent malignancy and the second leading cause of cancer deaths among males in the Western world. The clinical course of the disease is highly complex, and genetic factors underlying tumorigenesis are poorly understood. The challenge that lies ahead is to identify the important gene(s) that causes adenocarcinoma of the prostate. Chromosomal findings by cytogenetic and molecular methods, including Southern blotting, microsatellite analysis, fluorescence in situ hybridization, and comparative genomic hybridization, revealed a high frequency of chromosomal aberrations of heterogeneous nature, including: -1, +1, -1q, +4, -6q, -7, +7, -8, -8p, -8q, +i(8q), -9, -9p, -10, +10, +11, -12, -13q, -16, -16q, +16, -17, +17, +17q, -18, +18, -18q, +19p, +20q, +X, -Xq, -Y, and +Y. Specific chromosomal regions of alterations were 1q24-25, 2cen-q31, 5cen-q23.3, 6q14-23.2, 7q22-q31, 8p12-21, 8p22, 8q24-qter, 10q22.1, 10q23-25, 11p11.2, 16q24, 17p13.1, 18q12.2, and Xq11-12. Recently, a predisposing gene for early onset has been localized on 1q42.2-43. The losses of heterozygosity at specific chromosomal loci from chromosomes 5q, 6q, 7q, 8p, 8q, 10q, 13q, 16q, 17p, 17q, and 18q are generally correlated with poor prognosis in advanced tumor stage. In addition, an abnormal function of known tumor suppressor genes from these regions have been observed in prostate cancer. Although, the amplification of the androgen receptor gene at Xq11-13 and HER-2/neu gene at 17q11.2-q12 are novel findings, no single gene has been implicated in harboring prostate cancer. Frequent inactivation of PTEN/MMAC1 tumor suppressor gene at 10q23, MXI-1 at 10q25, KAI-1 at 11p11.2, Rb at 13q14.2, and p53 at 17p13.1 and deregulation of c-myc oncogene at 8q24 have recently been the subject of intense scrutiny and debate.

Is there an increased risk of second primaries following prostate irradiation?

PURPOSE

To assess the risk of developing a second primary cancer following prostate irradiation compared to the underlying risk in patients with prostate cancer.

METHODS AND MATERIALS

The baseline rate of secondary cancers following prostate cancer was obtained from a study of 18,135 patients from the Connecticut Tumor Registry, of whom only 12.5% received radiotherapy. These patients, with a mean age of 72 and a mean follow-up of 3.9 years, were compared to a cohort of 543 patients (median age 70) with similar follow-up (median 3.9 years), all of whom were treated with definitive radiotherapy at Fox Chase Cancer Center. The possible association between various covariates (age, dose, palpation stage, field size, Gleason score, pretreatment PSA) and the development of a secondary cancer was assessed.

RESULTS

1,053 of 18,135 patients (5.8%) in the Connecticut Tumor Registry developed a second primary cancer compared with 31 of 543 (5.7%) patients treated with prostate radiation (p = 0.99). Although this risk increases gradually over time, it is not significantly different, at any time period, between the two groups of patients. Of the 31 secondary primaries in the irradiated group, 82% had a history of tobacco and/or alcohol use. Only melanomas were significantly increased compared to the expected rate in an age-matched population (p < 0.001). Five of the 31 secondary cancers occurred within the radiation field (four bladder, one colon), four within 3 years and only one occurred 9 years after radiotherapy. No association was found between age (<70 vs. > or =70 and as a continuous variable), dose (<74 vs. > or =74 Gy), palpation stage (<T2C vs. > or =T2C), field size (prostate vs. pelvic), radiation technique (conventional vs. conformal), Gleason score (2-6 vs. 7-10), or pretreatment PSA (<15 vs. > or =15 and as a continuous variable) and the risk of developing a second primary. Although a lower radiation dose (as a continuous variable) correlated with an increased risk of developing a secondary cancer (p = 0.04), this phenomenon is likely due to differences in follow-up time.

CONCLUSION

Up to at least 10 years, there is no increased risk of developing a second primary cancer following prostate irradiation compared to the baseline rate from prostate cancer itself. This risk is not higher in younger patients with localized disease (<T2C), who often must choose between surgery and radiation. The vast majority of secondary cancers occurred outside of the radiation field (84%) and/or within 3 years of radiotherapy (97%), suggesting they were not caused by radiation. Most of these patients had lifestyles with predisposing risk factors. Patients with prostate cancer manifested a significantly increased risk of developing melanomas, suggesting that they may benefit from patient education and skin screening examinations.