Screening for anal intraepithelial neoplasia among men having sex with men attending a designated Sexually Transmitted clinic in South India

Ø Men who have sex with men (MSM), is at greater risk for anal cancer and its precursor lesions when compared to men in the general population.

Ø Incidence of anal cancer in MSM has been reported to be higher than the incidence of cervical cancer in women with the highest rates among HIV positive MSM in whom anal cancer rates are the highest.

Ø Almost upto 20% of patients with anal cancer are asymptomatic and the most common symptom reported is rectal bleeding which would be often attributed to haemorrhoids thereby further delaying the diagnosis. Epidemiologic studies have indicated that a             prolonged preclinical phase often precedes the onset of anal cancer in high-risk groups.

Ø The basic principle behind screening for anal dysplasia is the early identification of these proliferating cell lines that have established irreversible high-grade dysplasia or local invasive disease.

Ø Hence providing screening methods, especially for high-risk individuals, would provide an opportunity for earlier diagnosis and management of HPV and associated cytologic changes. These screening methods include anal Pap smears often combined with digital anorectal examination (DARE), to detect both palpable anatomic lesions as well as cytologic abnormalities followed by HPV detection and high resolution anoscopy and biopsy.

Ø Anal Pap smears have been found to have a sensitivity of 69% to 93%, and  specificity of 32% to 59% and have been reported to be cost-effective in detecting abnormal lesions in high-risk patients.However, the role of HPV detection in anal dysplasia screening remains controversial.

Ø HPV related anal dysplasia and cancer is a public health concern, just like other sexually transmitted infections and currently there are no national recommendations available for their screening. Due to the high rates of anal dysplasia and cancer in MSM, this study is proposed to identify the prevalence of AIN and to implement an effective screening program for this high risk population.

Aim:

To study the usefulness of screening tests and propose a screening strategy for the detection of anal intraepithelial neoplasia (AIN) and its epidemiologic correlates among men having sex with men (MSM) attending a designated sexually transmitted infection (STI) clinic in South India.

Objectives:

Among men having sex with men (homosexual and bisexual) attending a   designated STI clinic in South India,

1.     To study the frequency of anal intraepithelial neoplasia and its epidemiologic correlates.

2.     To study the diagnostic accuracy of anal “Pap†smears with p16 immunostaining, human papilloma virus (HPV) detection, and HRA findings in comparison with HRA guided biopsy findings as gold standard to detect anal intraepithelial neoplasia.