Background Anal intraepithelial neoplasia (AIN), a human papillomavirus (HPV)-associated potential precursor lesion of anal cancer, is frequent among human immunodeficiency virus (HIV)-positive men who have sex with men (MSM). There is a paucity of data published on the progression of high-grade AIN to invasive cancer as well as on clinical and virological characteristics comparing anal margin and anal canal carcinoma.
Objectives To search for anal carcinoma and AIN in a large series of HIV-positive MSM, to assess treatment response of anal carcinoma, and to analyse lesional HPV spectrum of anal cancers.
Methods Detection of anal carcinoma and AIN was performed using cytology, high-resolution anoscopy, and histology in case of abnormal findings. Additionally, HPV analyses for 36 high- and low-risk α-HPV types were performed in patients with anal carcinoma.
Results In total, 446 German HIV-positive MSM were examined within an observation period of 5 years and 10 months. Of these, 116 (26·0%) patients had normal findings, 163 (36·5%) had low-grade AIN, 156 (35·0%) had high-grade AIN, and 11 (2·5%) had anal carcinoma as evidenced by the highest grade of cytology/histology. Five patients with anal cancer, who had refused treatment of their precancerous lesions, had progressed from high-grade AIN to invasive cancer within a median time of 8·6 months. All anal cancers carried high-risk α-HPV types. All five squamous cell carcinomas (SCCs) of the anal canal were HPV16 positive. In contrast, only one of the four anal margin SCCs were HPV16 positive (HPV31, HPV33 and HPV33 + HPV68 were found in the other three anal margin SCCs). HPV59 was found in two adenocarcinomas, one of which additionally carried HPV33. In contrast to the cancer biopsies, a broad spectrum of surface high- and low-risk HPV types was found in anal swabs of the patients. Surgical excision resulted in long-term disease control of all anal margin carcinomas, whereas combined chemoradiotherapy in carcinomas of the anal canal was associated with high recurrence rates, high toxicity, and high mortality.
Conclusions Anal carcinoma and AIN are frequent in HIV-positive men, even in patients participating in anal cancer prevention programmes. High-grade dysplasia in these patients can progress to invasive cancer within a short period of time. Anal margin carcinoma and anal canal carcinoma differ substantially in their lesional HPV spectrum, prognosis and treatment response.