Correlation of AgNOR count with biological behavior of N-Nitroso-N-Methylurea (NMU)-induced squamous cell carcinoma in Wistar rats

Gastric squamous cell carcinoma is one of the most common malignancies in human beings throughout the world. Assessment of proliferative aggressiveness of squamous cell carcinoma plays an important role in diagnostic, prognostic and therapeutic decisions on them. It is determined by both proliferative fraction and speed of neoplastic cells. AgNOR count is an important easily feasible histochemical technique to assess both proliferative fraction and speed of tumour growth. The present study was aimed at evaluating the ability of AgNOR count to assess proliferative speed of a tumour by correlating with pathomorphological parameters of tumour growths (grading, tumour volume, multinodularity, total number of neoplastic cells and survival period) induced in seven Wistar rats by intraperitoneal administration of N-Nitroso-N-Methylurea (NMU) at the dose rate of 50mg/kg b.wt. once per week for four weeks. Tumours were harvested on necropsy after the natural death of experimental rats. Out of total seven cases of gastric squamous cell carcinoma, four tumours were grade II and other three were of grade III. The t-test showed significantly higher mean values of mAgNOR count, mitotic figure count and different pathomorphological parameters of biological behavior i.e., tumour volume, multinodularity and total cell count in Grade-III compared to Grade-II gastric squamous cell carcinomas, indicating their biologically more aggressive growth. It was observed that mAgNOR count may be helpful in predicting real proliferative nature of a tumour and may help in taking diagnostic, prognostic and therapeutic decisions on gastric squamous cell carcinomas.