The etiology and epidemiology of anal cancer

Diagnostic problems in anal pathology

Anal squamous cell carcinoma and its precursor lesions are increasing in incidence in the United States and Europe. This trend predates human immunodeficiency virus/acquired immune deficiency syndrome and has been associated with persistent high-risk human papilloma virus (HPV) genotype infection, previous lower genital tract dysplasia/carcinoma, high frequency anoreceptive intercourse, heavy cigarette smoking, immunosuppression in solid organ transplant and immune disorders, and human immunodeficiency virus seropositivity. Screening protocols for at-risk patients are under active investigation and pathologists are often asked to assess anal canal and perianal biopsies for the presence of dysplasia and/or invasive carcinoma. Because underdiagnosis and overdiagnosis of anal cancer and precancer may lead to inappropriate treatment, it is important for the pathologist to be aware of current screening strategies, specific risk lesions, and the role of pathology in initial diagnosis and evaluation of anal biopsy and/or resection specimens. Standardized histologic criteria and uniform terminology should be used for reporting all anal canal and perianal squamous intraepithelial lesions. HPV subtyping, anal cytology, and recently identified biomarkers, such as p16 and Becton Dickinson ProEx C may provide additional information in problematic cases, but it is important to be aware of the limitations of these assays. HPV has been linked to all the major histologic subtypes of anal carcinoma (eg, basaloid, cloacogenic, transitional, etc.) and this association is strongest for anal canal lesions. With the possible exception of the microcystic pattern, histologic subtype does not seem to predict prognosis; and anal squamous cell carcinomas should be classified as either keratinizing or nonkeratinizing. Poorly differentiated squamous cell carcinomas have a worse prognosis and should be distinguished from poorly differentiated adenocarcinoma, melanoma, and neuroendocrine tumors. Very well differentiated squamous cell carcinoma with pushing margins (so-called giant condyloma of Buschke and Lowenstein) should be classified as verrucous carcinoma; this tumor shows aggressive local infiltration but does not metastasize. As all anal condylomata may harbor foci of high-grade dysplasia or invasive carcinoma, careful sectioning and complete histologic examination is required.

Tobacco smoking and risk of recurrence for squamous cell cancer of the anus

OBJECTIVE

Squamous cell cancer of the anus is associated with multiple risk factors, including infection with human papillomavirus, immunosuppression, chronic inflammation, and tobacco smoking, although there is little data on these factors for the prediction of recurrent disease. Here, we evaluated the risk of recurrence and mortality of anal carcinoma in association with tobacco smoking.

METHODS

We conducted a retrospective review of cases of anal carcinoma from two local hospitals. We obtained information on treatment response and cancer recurrence, as well as tobacco usage from medical records.

RESULTS

We identified 64 patients with squamous cell cancer of the anus, and 34 of these (53%) had a tobacco smoking history. Current smokers had higher carcinoma recurrence rates (11/34, 32%) than non-smokers (6/30, 20%). Overall mortality was 33% (21/64), and cancer-related mortality was 23% (15/64). Smokers were more likely to die from recurrence than non-smokers, with 45% of smokers dead compared to only 20% of non-smokers by 5 years after treatment.

CONCLUSION

Tobacco smoking appears to be associated with anal carcinoma disease recurrence, and is related to increased mortality. This data suggests that patients should be cautioned about tobacco smoking once a diagnosis of anal carcinoma is made in attempt to improve their long-term outcome.

Anal cancer: an overview

Anal 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.

Anal intraepithelial neoplasia and anal cancer in dermatological practice

Anal intraepithelial neoplasia is considered to be a precursor lesion of invasive anal cancer. It is now increasingly recognized in high-risk groups, such as men who have sex with men and HIV-infected patients. Human papillomaviruses are considered to be an important aetiological agent in both anal intraepithelial neoplasia and anal cancer. Dermatologists are likely to encounter these conditions among the differential diagnoses to be considered in high-risk patients presenting with perianal and anal lesions. Anal cancer rates are also increasing among the HIV-infected and HIV-non-infected population. The successful treatment of anal intraepithelial neoplasia may reduce the risk of subsequent development of anal cancer. However, current therapies for anal intraepithelial neoplasia may be associated with treatment-related morbidity and are not well validated. It is currently not proven that they reduce the likelihood of the development of anal cancer. Nevertheless, screening for anal intraepithelial neoplasia is being advocated for high-risk groups and may become standard dermatological care for these patients. In view of recent developments in the understanding of this condition, this article reviews the current understanding of anal intraepithelial neoplasia and its treatment from a dermatological perspective.

Role of human papillomavirus in squamous cell metaplasia-dysplasia-carcinoma of the rectum

Primary colorectal squamous cell carcinoma (SCC) and squamous dysplasia are uncommon and little is known about their pathogenesis. Most have been reported in association with ulcerative colitis and other chronic disease states. Although cervical and anal SCC have been strongly linked to human papillomavirus (HPV) infection, the role of HPV in rectal squamous carcinoma has not been well-examined. We evaluated 3 cases of primary rectal SCC for the presence of high-risk HPV by immunohistochemistry for p16(INK4A), in situ hybridization, and polymerase chain reaction. HPV type 16 was detected by polymerase chain reaction in all cases. In addition, all cases exhibited diffuse strong reactivity for p16(INK4A) and punctate nuclear staining by Ventana HPVIII in situ hybridization. The presence of HPV 16 in all three cases suggests that high-risk HPV infection is a risk factor for rectal SCC, particularly in patients with underlying chronic inflammatory disease processes or altered immune status. Further studies are warranted to determine if SCC occurring more proximal in the colon are also HPV-dependent or occur via another, HPV-independent pathway.

Bilan préthérapeutique initial du carcinome épidermoïde invasif de l’anus

Anal epidermoid carcinoma is a rare malignant tumor, comprising less than 5% of all carcinomas of the colon, rectum, and anus. The primary therapy now includes radiotherapy, often in combination with chemotherapy. Radical surgery is now rarely indicated. Therapeutic indications are based on locoregional staging, the presence of visceral metastases and an evaluation of the medical history. Anorectal endosonography is helpful in evaluating locoregional extension. In addition, magnetic resonance imaging, positron emission tomography scanning and inguinal sentinel lymph node procedure should play a role in a more selective approach in patients with anal carcinoma.

High prevalence of human papillomavirus infection in the anus, penis and mouth in HIV-positive men

Human papillomavirus (HPV) types are associated with squamous cell cancers. HIV infection is linked with a higher prevalence of anal HPV infection. It is important to assess whether HPV is present in other body parts involved in sexual practices to establish a cancer prevention program. A high prevalence of high-risk HPV types was present in the anus, penis and mouth (78, 36 and 30%, respectively) in a cohort of HIV-infected males (men who have sex with men and heterosexual), without evidence of pathology in these areas.