Saturday, February 6, 2016

Anal Cancer & Intraepithelial Neoplasia Screening: A Review

This review focuses on the early diagnosis of anal cancer and its precursor lesions through routine screening. A number of risk-stratification strategies as well as screening techniques have been suggested, and currently little consensus exists among national societies. Much of the current clinical rationale for the prevention of anal cancer derives from the similar tumor biology of cervical cancer and the successful use of routine screening to identify cervical cancer and its precursors early in the disease process. It is thought that such a strategy of identifying early anal intraepithelial neoplasia will reduce the incidence of invasive anal cancer. The low prevalence of anal cancer in the general population prevents the use of routine screening. However, routine screening of selected populations has been shown to be a more promising strategy. Potential screening modalities include digital anorectal exam, anal Papanicolaou testing, human papilloma virus co-testing, and high-resolution anoscopy. Additional research associating high-grade dysplasia treatment with anal cancer prevention as well as direct comparisons of screening regimens is necessary to develop further anal cancer screening recommendations.

…[T]here are populations with disproportionate prevalence of anal cancer that are more conducive to group-wide screening. Immunosuppressed patients are increasingly recognized as one of the groups at highest risk for anal cancer[,]. Much of this recognition has developed over the rise of the HIV/AIDS epidemic in the last three decades. Infection with HIV is associated with a 30-fold increased lifetime risk in anal cancer and a 4-fold increase in 5-year mortality[,]. Although sexual practices - particularly anoreceptive intercourse - have been previously associated with anal cancer, recent studies have shown that the risk of anal cancer in HIV-positive individuals exists independently of sexual practices[,]. The risk of anal dysplasia progression appears to correlate directly with degree of immunosuppression as measured by T cell CD4+ count with a cell count less than 200 cells/mm3 most closely associated with increased prevalence[-]. Surprisingly though increased access to highly active antiretroviral therapies has not eliminated the increased risk of anal cancer in the HIV-infected population. It is thought that immune system restoration does not entirely eliminate the increased risk of dysplastic changes and then antiretroviral treated patients are living longer thereby increasing the lifetime interval risk of disease incidence[]...

Below:  San Francisco algorithm for anal cancer screening of high-risk patients. ASC-US: Atypical squamous cells of undetermined significance; LSIL: Low-grade squamous intraepithelial lesions; HSIL: High-grade squamous intraepithelial lesions; Pap: Papanicolaou; HRA: High-resolution anoscopy; AIN: Anal intraepithelial neoplasia

Below:  Johns Hopkins Hospital algorithm for anal cancer screening of high-risk patients. Pap: Papanicolaou; HRA: High-resolution anoscopy; ASC-H: Atypical squamous cells of undetermined significance, cannot rule-out high-grade dysplasia; AIN I: Anal intraepithelial neoplasia I; PCP: Primary care physician; LSIL: Low-grade squamous intraepithelial lesion; AIN II: Anal intraepithelial neoplasia II; AIN III: Anal intraepithelial neoplasia III.

Full article at:

Ira L Leeds, Sandy H Fang, Ravitch Division, Colon and Rectal Surgery, Department of Surgery, Johns Hopkins Hospital, Baltimore, MD 21287, United States
Author contributions: Leeds IL and Fang SH contributed to conception and design; Leeds IL contributed to data collection and analysis, and drafting manuscript; Fang SH contributed to critical revision.
Correspondence to: Ira L Leeds, MD, MBA, Ravitch Division, Colon and Rectal Surgery, Department of Surgery, Johns Hopkins Hospital, 600 N Wolfe Street, Tower 110, Baltimore, MD 21287, United States. ude.imhj@sdeeli

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