Diagnosis and Therapy of Anal Carcinoma

Abstract

Diagnosis and Therapy of Anal Carcinoma Summary. The squamous cell carcinoma of the anorectum is rare and subdivided into perianal, anal canal and combined carcinomas. Persistent infection with a high-risk human papillomavirus (HPV) is believed to be the main cause for the development of anal cancer. Therefore, the incidence in high-risk individuals (e.g. immuno-compromised patients or patients living with HIV) is much higher than in the general population. Nevertheless, a nearly three-fold overall increase was observed within the last three decades. The diagnosis is often made by chance as anal carcinoma presents with unspecific symptoms which could be attributed to many other proctological diseases, especially haemorrhoids. The diagnosis is confirmed by histology using biopsies or excisional biopsies. The subsequent staging requires a detailed documentation of the tumor's location and size as well as an overall examination focusing on palpation of the groin. Sphincter involvement in small lesions can be assessed by endoluminal ultrasound or alternatively by an angulated magnetic resonance imaging of the anal canal/pelvis. A computed tomography scan of the thorax and abdomen is usually performed to rule out a metastatic disease. Positron emission tomography-computed tomography is useful for detection of lymph node (LN) involvement and to accurately define the stage prior to treatment. The therapy of anal carcinoma requires a multidisciplinary approach. In most patients, primary treatment consists of chemoradiotherapy (CRT), which improved 5-year overall survival since its introduction in 1974. A surgical approach is reserved for small perianal lesions without sphincter infiltration, LN or distant metastasis. Furthermore, in recurrent or persistent carcinomas after CRT salvage surgical treatment is recommended. In some cases (obstruction, fistula formation) a deviation colostomy is required. Follow-up clinical and imaging evaluation should follow recommended guidelines and should involve primary physicians in addition to members of the multidisciplinary treatment team. Until now, the impact of HPV immunization on anal carcinoma is still unclear despite having been proven effective in preventing anal intraepithelial neoplasia.