AgNOR count and its diagnostic significance in cervical intraepithelial neoplasia

The misery of women due to cervical cancer, which is the commonest cancer in women in a developing country like ours is a scourge of humanity. Early detection and management of squamous intraepithelial lesions (SIL) is the best approach to achieve control over cancer cervix. Cytological screening by Pap smear has brought down the incidence of cervical cancer in developed countries 1. Unfortunately cytology fails to identify high risk low grade SIL (LSIL) and high grade SIL (HSIL) which would progress to invasive cancers. Such information can be provided by a molecular tumor marker 2. One such molecular tumor marker is AgNOR which stands for silver stained (Ag) nucleolar organizer regions (NORs). NORs are loops of DNA present in nucleus of cell on acrocentric chromosomes 13, 14, 15, 21 and 22. NORs are associated with argyrophilic proteins (having affinity for silver) like polymerase C23 and B23. Simple silver staining technic can recognize these argyrophil associated proteins. They appear as black dots after silver staining in nucleolar and extranucleolar regions 5. In a normal cell 20 black dots of AgNORs should be seen (2 per arm of chromosome i.e. 2 x 10 = 20) but only one or two dots are seen as the dots are tightly packed 4. As we move from normal cells towards the dysplastic cells and malignant cells, the amount of DNA increases, and the number of AgNOR dots (AgNOR count) also increases. With this knowledge in background, this study was undertaken to determine AgNOR counts in CIN I, CIN II and CIN III lesions and to establish their diagnostic role in preinvasive lesions in the setup of a developing nation like ours.