Cellular DNA content and prognosis in surgically treated squamous carcinoma of the larynx

Real-time PCR hTERT mRNA pattern in tumor core, edge, resection margin, and lymph nodes in laryngeal tumors: relation to proliferative index and impact on prognosis

BACKGROUND

The immortalizing enzyme, telomerase, has been linked to carcinogenesis and is being targeted as a novel molecular marker. This study investigated the pattern of human telomerase reverse transcriptase (hTERT) mRNA by real-time polymerase chain reaction (PCR) in tumor core, edge, and safety margin of laryngeal tumors and related lymph nodes, as well as their relation to the proliferative index (PI) and their impact on prognosis.

MATERIAL AND METHODS

This prospective study included 35 patients with laryngeal carcinoma who were surgically treated by total or partial laryngectomy. Collected tissues from tumor core, edge, resection margin, and lymph nodes were examined by flow cytometry and real-time PCR quantification of hTERT mRNA.

RESULTS

The PI showed a statistically significant difference between the contrasted parts (P = 0.04). The highest median for PI was found in the tumor edge samples (31.3), followed by the tumor core (27.5), the resection margin (21.4), and finally the lymph nodes (10.3). There was no significant difference with regard to the ploidy patterns or the synthetic phase fraction (SPF) among the different tissue parts. Real-time PCR hTERT mRNA patterns showed that the highest median for hTERT mRNA level (copies/mug RNA) was in the tumor core (70.5), followed by the tumor edge (36.5), the resection margin (17.3), and finally the lymph nodes (4.4). There was a statistically significant difference with regard to the hTERT mRNA patterns among the different tissue parts (P = 0.04). Tumor differentiation, tumor edge ploidy, and tumor edge hTERT levels were significantly different between survivors and non-survivors, while tumor core S-phase fraction and tumor core PI significantly altered the disease-free survival rate.

CONCLUSION

hTERT mRNA may potentially be used for molecular reevaluation of the safety margin for conservational laryngeal surgery, and as a prognostic factor for overall survival especially if determined in samples taken from the growing edge of tumors.

Prognostic factors in carcinoma of the larynx: relevance of DNA ploidy, S-fractions and localization of the tumour

The influence of the cell cycle profile and the site of the primary tumour on the overall survival were examined in 36 patients with squamous cell carcinoma of the larynx. DNA ploidy (p = 0.0091), the overall proliferative activity (p = 0.0001), the overall proliferative activity of diploid tumour cells (p = 0.0017) and primary tumour site (p = 0.0008) were found to be significant single prognostic factors of the overall survival. Multivariate analysis showed that only the overall proliferative activity was prognostically significant (p = 0.013). The results of the study show that the supraglottic site of the tumours correlates significantly with DNA ploidy (p = 0.0334) and the overall proliferative activity of tumour cells (p = 0.0159), whereas the correlation with proliferative activity of diploid tumour cells (p = 0.1416) has not been confirmed by this study. Glottic tumours showed a prognostically significant correlation with the overall proliferative activity (p = 0.0037) and proliferative activity of diploid tumour (p = 0.0054). Such a prognostic correlation was not found for DNA ploidy (p = 0.6542).

Role of DNA measurements of head and neck tumors

The measurement of DNA ploidy has been used as a tool to try to determine the prognosis of many neoplasms. DNA ploidy can be determined by flow cytometry or image analysis of a tumor. In squamous carcinomas of the head and neck, a poorer prognosis has been associated with nondiploid tumors. Similar results have been obtained from studies of salivary gland neoplasms. The role of DNA ploidy as a provider of independent information has yet to be determined. With rarer head and neck tumors, measurement of tumor ploidy has yet to be established as a valuable adjunct to routine light microscopic study.

Cervical lymph node status and survival in laryngeal carcinoma: prognostic factors

Elective cervical lymphadenectomy often is performed for laryngeal carcinoma to eliminate metastatic disease that escapes clinical and radiographic detection. We investigated characteristics of the primary tumor that might predict cervical lymph node status. We obtained archival tissue from 88 laryngectomies--65 with concurrent cervical lymphadenectomies. Of the 40 clinically negative necks that were dissected, 17% showed lymph node metastasis by pathologic examination. The primary tumors were examined immunohistochemically for expression of epidermal growth factor receptor (EGFR), p53, cathepsin D, proliferating cell nuclear antigen (PCNA), and Ki-67-specific antigen, and by flow cytometry for DNA ploidy-cell cycle analysis. Seventy-seven percent of the cases showed aberrant p53 staining, 99% expressed EGFR, 40% produced cathepsin D, 29% were aneuploid, and 54% had a moderate or high synthesis phase fraction (SPF). High grade, aneuploidy, and tumor vascular invasion independently predicted cervical node metastasis (p < .04 each). Supraglottic locale (p < .16) and a raggedly infiltrating invading margin (p < .13) were weakly associated with node positivity. Advanced clinical T status, the expression of EGFR, p53, and cathepsin D, the PCNA and Ki-67 indices, and SPF did not correlate with node metastasis. The presence of cervical node metastasis predicted poor disease-free (p < .005) and overall survival (p < .04). Advanced clinical T status correlated with brief overall survival (p < .02). Tumor site, histopathologic parameters, ploidy, SPF, PCNA and Ki-67 indices, and the expression of p53, EGFR, and cathepsin D did not affect survival. The presence of vascular invasion, high grade, and aneuploidy may help identify which patients would benefit from elective cervical lymphadenectomy. The correlation of cervical lymph node status and clinical T category with survival confirms the results of previous studies.

Proliferating cell nuclear antigen (PCNA) expression and nuclear DNA content in predicting recurrence after radiotherapy of early glottic cancer

Proliferating cell nuclear antigen (PCNA) is a DNA replication protein maximally elevated in late G1 and S phases of the cell cycle. By using monoclonal antibodies, the expression of PCNA can be quantified and the rate of tumour cell proliferation estimated. The degree of DNA aberration in a tumour cell population reflects its genetic instability and has been implicated as a prognostic factor in an increasing number of solid tumours. The nuclear DNA content can be assessed by densitometric image cytometry DNA analysis. Both PCNA and DNA analysis can be performed on histological sections from paraffin embedded biopsies. In search of efficient and reproducible methods to identify early glottic cancers with increased risk for recurrence after radiotherapy, the PCNA expression as well as the DNA content of the diagnostic biopsies from 28 T1N0M0 glottic cancers were assessed. The group of tumours which recurred locally after radiotherapy displayed lower PCNA expression and higher DNA aberration than the group of tumours which were cured. Moreover, a combination of both parameters improved the possibility to discriminate the two groups. For T1 glottic cancer displaying high grade of genetic instability or low grade of proliferation, treatment regimes other than radiotherapy and closer follow-ups could be considered.