Association of DNA pattern of metastatic lymph node with disease free survival in patients with intraoral squamous cell carcinoma.

BACKGROUND AND OBJECTIVE Intraoral squamous cell carcinoma (OSCC) is one of the common tobacco related cancers affecting Indian population. These tumours are slow growing, endophytic and are mostly well differentiated. Cervical lymph node is the common site of metastasis of these tumours. In most of the patients cervical lymph node metastasis rather than the primary tumour, affects prognosis. However, no reports are available on the DNA pattern of the metastatic lymph nodes in patients with intraoral squamous cell carcinoma. Therefore, the present study was undertaken to observe DNA pattern of primary tumours and their corresponding metastatic lymph nodes and its association with the clinicopathological parameters and prognosis. METHODS DNA flow cytometry was successfully carried out on 68 paraffin embedded specimens of the primary tumours and their 22 corresponding metastatic cervical lymph nodes. The findings were evaluated for their possible association with clinicopathological features of the tumour and disease free survival of patients with intraoral carcinoma. RESULTS Analysis of nuclear DNA patterns revealed 32 (47.0%) diploidy and 36 (52.9%) aneuploidy in primary tumours whereas metastatic lymph nodes showed 7 (31.8%) diploidy and 15 (68.1%) aneuploidy. The aneuploidy group in metastatic lymph node had significantly higher S phase fraction (SPF) (P<0.01) and poor histological grade (P<0.002) as compared to their counterparts with diploidy. DNA pattern of metastatic lymph node further showed a significant association with disease free survival in the log rank test. Aneuploidy and high SPF in metastatic lymph node was found to be associated with early recurrence while DNA pattern of the primary tumour did not show significant association with the disease free survival. INTERPRETATION AND CONCLUSION It may be concluded that aneuploidy and high SPF in metastatic lymph node might be considered as an important discriminatory risk factor in patients with similarly staged intraoral squamous cell carcinoma.