Expression of p16 INK4a and human papillomavirus 16 with associated risk factors in cervical premalignant and malignant lesions.

Introduction: Human papilloma virus (HPV) which is causative factor for cervical cancer may interact with p16 leading to malignant transformation of cervical epithelial cells. The present study was conducted to assess the immunoexpression of p16 INK4a in premalignant and malignant lesions of cervix and to correlate it with HPV 16 expression. It was also intended to study the various risk factors which may be associated with cervical cancer in this north Himalayan region of India.

Material and Methods: The study included 50 cases of premalignant and malignant cervical lesions and 50 controls diagnosed on histopathology over a period of one year. All the relevant clinical details were noted and both cases and controls were subjected to HPV 16 and p16 INK4a immunohistochemical staining.

Results: 67% of subjects (including cases and controls) and 94% of the cases were positive for HPV 16 expression. p16 INK4a expression was negative in all the controls, positive in 96% of invasive cancer, 66.6% in HSIL and 37.5% in LSIL.

Conclusion: Cervical cancer is associated with low socio economic status, illiteracy, smoking, early age of marriage and conception in north Himalayan region of India. HPV 16 infection is positive in both cases and controls indicating high prevalence of HPV 16 in this region. Neoplastic transformation by HPV is identified by over expression of p16 INK4a in premalignant and malignant cases. The immunopositivity of p16 INK4a increases with the severity of cervical lesions and thus may play an important role in stratification of premalignant and malignant lesions.