Karyotypic findings in two cases of moderately differentiated squamous cell carcinomas of the penis

P53 Codon 72 Polymorphism and Risk for Squamous Cell Carcinoma of the Penis: A Caucasian Case-Control Study

Squamous cell carcinoma of the penis is a rare but often aggressive disease. A large proportion of penile cancers are associated with HPV infection, mainly with HPV high-risk subtypes 16 and 18. From other HPV-related malignancies a link between a functional SNP in the p53 gene (rs1042522, p.Arg72Pro) and a higher disease risk in the presence of HPV is documented. The p53 p.Arg72 variant was described as a risk factor for developing a malignancy in combination with the presence of HPV as the p.72Arg variant is more prone to HPV E6 protein-mediated degradation than the p.72Pro variant. For penile carcinoma there are only sparse data available on this topic. We therefore analyzed the distribution of this p53 codon 72 SNP in a cohort of 107 penile cancer patients and a healthy control group (n=194) using Restriction Fragment Length Polymorphism (RFLP) analysis. After DNA isolation a PCR amplicon including the variant nucleotide was generated. Based on the variant nucleotide this amplicon can be cleaved into two parts or remain unaffected by a restriction enzyme. Subsequent electrophoresis allowed the discrimination of SNP alleles in the investigated sample. Comparison of the allelic variants revealed no significant differences in the distribution of this SNP between cases and controls (p=0,622). There was also no difference in SNP distribution between cases with/without HPV infection (p=0,558) or histologic variants (p=0.339). In order to strengthen the impact of our data we performed a combined analysis of all published data on this topic with our results. This ended up in SNP distribution data from 177 cases and 1149 controls. Overall, there were also no significant differences in the allelic distribution of the p53 codon 72 SNP between either cases and controls (p=0,914) or HPV-positive and HPV-negative cases (p=0,486). From this most comprehensive data available to date we conclude that there is no influence of the p53 codon 72 SNP on the risk of development of penile carcinoma in Caucasians even in the presence of HPV.

Molecular prognostic factors in penile cancer

OBJECTIVES

Penile cancer is a rare tumour in developed countries but more common in South America and East Africa. Although pathological prognostic factors have been established, there is great interest in evaluating molecular markers which correlate with prognosis and outcome.

METHODS

We have reviewed the current status of our understanding of the molecular biology of penile cancer in order to identify established and potential prognostic factors in penile cancer. We have conducted an extensive literature search to review the current understanding of the role of prognostic markers in penile cancer.

RESULTS

Although several markers have been evaluated, currently the clinical application of these markers is limited. HPV positive tumours show a variable prognostic outcome. P53 status may correlate with survival in T1 disease but further studies are required to establish the link to lymph node spread.

CONCLUSIONS

Pathological variables are well-established but further work is required to investigate the role of molecular markers. The development of molecular prognostic markers is important for the surveillance of patients and prediction of lymph node involvement as well as a prognostic marker for survival.

Screening of microsatellite markers in penile cancer reveals differences between metastatic and nonmetastatic carcinomas

Penile cancer, observed only rarely in the western world, represents a carcinoma that may be cured by resection of primary lesion and in case of lymph node metastasis by early lymph node dissection. This early inguinal lymphadenectomy bares a significant better survival even in cases of nonpalpable lymph nodes, but carries also a high risk of overtreatment, especially in lower tumor stages. Due to the low incidence, only few data are available on the molecular genetic background of this tumor, especially concerning tumor progression and metastasis. Therefore, we studied 62 microsatellite markers in 28 penile carcinomas searching for markers predicting progression or outcome. LOH in more than 25% of primary tumors was found on six different chromosomes, including 2q, 6p, 8q, 9p, 12q and 17p13. Statistically significant correlations could be established in D6S260 to clinical outcome and in markers from chromosomes 6, 9 and 12 to tumor stage and metastasis. These regions are worthy for further analysis concerning tumor suppressor genes and metastasis suppressor genes.

Genetic imbalances in 26 cases of penile squamous cell carcinoma

To obtain more information on chromosomal changes in the up-to-now poorly studied tumor class of penile squamous cell carcinoma (SCC), we performed a comparative genomic hybridization study of 26 cases of this rare tumor. DNA sequence copy number alterations (CNAs) very similar to those detected in other SCC types, such as oral and esophageal SCC, were noted. The most common copy number gains were found in 8q24, 16p11-12, 20q11-13, 22q, 19q13, and 5p15, and the most common deletions were detected in 13q21-22, 4q21-32, and along the X chromosome. Classifying the patients according to the number of CNAs showed a possible correlation with clinical outcome.