Malignant anal tumours in the Chinese population in Hong Kong.

Malignant anal tumours are rare cancers but are particularly common in Switzerland, Poland and Brazil. Very little is known about this condition in the Chinese population. A retrospective study, covering an 11-year period, was performed. A total of 18 patients were treated at the Prince of Wales Hospital, Hong Kong. There were eight squamous cell carcinomas, seven adenocarcinomas and one each of adenosquamous carcinoma, malignant melanoma and leiomyosarcoma. Bleeding per rectum, with or without perianal pain, was the main presenting symptom. Abdominoperineal resection was the treatment modality used in most cases. Adenocarcinomas, seen mainly in males, accounted for about 39% of cases, a figure much higher than that published elsewhere. Another 44% of patients, predominantly females, had squamous cell carcinoma. None had a positive past history of sexually transmitted disease. The local prevalence of HPV infection is much lower than in the Western world, and the role of HPV in the oncogenesis of anal tumours in the Chinese population awaits elucidation.