Anal Cancer: An Overview

Abstract

LEARNING OBJECTIVESAfter completing this course, the reader will be able to:1. Discuss the epidemiology of and the risk factors for anal cancer.2. Outline standard treatment for anal cancer and describe its complications.3. Understand the issues related to treating HIV-positive patients with anal cancer.Access and take the CME test online and receive 1 AMA PRA Category 1 Credit ™ at CME.TheOncologist.com CME CME ABSTRACTAnal cancer is a rare tumor with an incidence that has been rising over the last 25 years. The disease was once thought to develop as a result of chronic irritation, but it is now known that this is not the case. Multiple risk factors, including human papillomavirus (HPV) infection, anoreceptive intercourse, cigarette smoking, and immunosuppression, have been identified. HIV infection is also associated with anal cancer; there is a higher incidence in HIV-positive patients but the direct relationship between HIV and anal cancer has been difficult to separate from the prevalence of HPV in this population. HIV infection is also associated with anal cancer; there are increasing numbers of HIV-positive patients being diagnosed with the disease. Treatment of anal cancer prior to the 1970s involved abdominoperineal resection, but the standard of care is now concurrent chemoradiation therapy, with surgery reserved for those patients with residual disease. We present a case of anal cancer followed by a general discussion of both risk factors and treatment. The Oncologist 2007;12: 524 -534 Disclosure of potential conflicts of interest is found at the end of this article. CASE PRESENTATIONA 63-year-old man with a past medical history significant for HIV managed with highly active antiretroviral therapy (HAART) (last CD4 count, 458) and anal squamous cell carcinoma in situ resected in 2000 presented for a routine colonoscopy in July 2006. The examination revealed a 12-mm nodule in the rectum, which was biopsied; pathology revealed invasive squamous cell carcinoma. Subsequent proctoscopy revealed a firm 2-cm mass located just beyond the dentate line. Transrectal ultrasound revealed evidence of invasion. Staging computed tomography (CT) scan revealed numerous low attenuation lesions in the liver concerning for metastasis but no evidence of abdominal or pelvic adenopathy. The patient was referred to gastrointestinal oncology to discuss treatment options.

Human papillomavirus genotypes in anal intraepithelial neoplasia and anal carcinoma as detected in tissue biopsies

“…11 Anal carcinoma and AIN have both been linked to HPV infection, 1,2,12,13 of which over 100 genotypes have been identified. At least 40 subtypes are known to infect the anogenital mucosa with variable neoplastic risk.…”

Anal Squamous Cell Carcinoma in African Americans with and without HIV: A Comparative Study

“…Squamous cell carcinoma (SCC) represents the majority of all anal carcinomas [2,3]. Several risk factors have been associated with the development of anal carcinomas such as lifetime number of sexual partners, female gender, human papillomavirus (HPV) infection, human immunodeficiency virus (HIV) infection and men who have sex with men (MSM) [4][5][6].…”

Early Impact and Performance Characteristics of an Established Anal Dysplasia Screening Program: Program Evaluation Considerations

“…Of these potential endpoints, Prorok concluded that "there is only one outcome variable known to be valid: the cancer mortality rate", defined as "the number of cancer deaths per unit of time, per unit of population at risk." [10] The pretreatment prognosis for IAC is determined, in part, by TNM stage, location, cell differentiation, and comorbid conditions including HIV related immunosuppression [48][49][50][51]. Practice guidelines of the National Comprehensive Cancer Network [2] recommend initial local excision for stage T1,N0 (≤ 2 cm diameter, no regional lymph node metastases) anal margin carcinomas and chemoradiation for T1-2, N0 disease for anal canal carcinomas or anal margin carcinomas with positive margins at resection.…”