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Anal cancer

Incidence increasing with an estimated 8,200 cases  per year in US

4% of all lower gastrointestinal cancers, and 1% of all G.I. cancers.

Historically associated with older women, particularly in the urban and HIV populations.

Increasing risk in men and women in the U.S. at about 3%/year and among white women 4% and among black men 6%.

Slight female predominance 1.5:1.

Estimated 6239 cases and 780 deaths attributed to AC in 2012.

Incidence of squamous cell carcinoma of the anus in white males 0.71 per 100,000 increasing approximately 2.6% per year from years 1993-1996.

In 2006 the incidence rate per 100,000 individuals was 1.5 (SEER).

The incidence of squamous cell carcinoma of the anal canal continues to rise annually in the US by 2.2% per year.

The incidence in homosexual men estimated to be 25-37 cases per 100,000 men, with a relative risk of anal malignancy 84 times that of the general population in homosexual men with AIDS.

Among homosexual men with genital warts the relative risk of developing such a lesion is 12.6.

Risk factors include persistent HPV infection a history of anal condylomas and immunosuppression therapy or HIV infection.

More than 90% of anal cancer cases are linked to HPV.

The risk of anal cancer is rising with data suggesting that persons engaging in certain sexual practices, such as receptive anal intercourse, or persons with a high lifetime number of sexual partners are at an increased risk of anal cancer.

These practices may have led to an increase in the number of individuals at risk for infection with human papillomavirus (HPV).

HPV infection is strongly associated with anal cancer development and may be a necessary step in its carcinogenesis,

In HIV positive patients the risk for developing anal squamous cell carcinoma is 40-80 fold higher compared to the general population.
Worse colostomy free survival and higher recurrence rates are associated with lower post treatment CD4 count, as Immunity plays a role in both the development of this lesion and increased rate of recurrence among patients with HIV.

Squamous cell carcinoma accounts for approximately 85% of all cases of AC.

Squamous cell carcinoma of the anal canal is a malignancy comprising only 1.5% of all gastrointestinal malignancies.

The remaining cases of anal carcinoma are adenocarcinoma 10%, and other types 5%.

Squamous cell cancer of the anus develops in patients with genital warts with a latent period of 5-40 years.

Incidence in women about 0.95 per 100,000.

Recent studies reflect human papillomavirus as the cause of anal intraepithelial neoplasia, and anal cancer frequently seen in young patients involved in receptive anal intercourse, in patients with HIV and in individuals with multiple sexual partners.

Evidence is accumulating indicating that oncogenic types of human papillomavirus, subtypes 16, and 18 are etiological linked to squamous cell carcinoma of the anal canal.

Incidence in the general population is 0.9 per 100,00 people.

Incidence in men involved in receptive anal intercourse is 35 per 100,00 persons.

Regional nodes are the inguinal, internal iliac, perirectal lymph nodes.

Tumors below the dentate line drain to the inguinal and femoral nodes and tumors above the dentate line drain into the perirectal and paravertebral nodes.

Evaluation includes the direct visualization of the anal mass with physical exam and colonoscopy to determine tumor size, location and extent.

CT scans were useful to assess invasion into surrounding organs and involvement of pelvic or inguinal lymph nodes.

Women require full gynecological examination to assess local invasion into the posterior vagina and to ascertain the presence of HPV associated conditions.

Because of the entire sensitivity in detecting regional lymph node involvement PET scan is increasingly commonly used for staging prior to treatment.

Surgical management with and abdominal perineal resection was formally used and has been replaced by chemoradiation using 5-FU/mitomycin squamous cell lesions.

Combination chemotherapy and radiation demonstrates complete pathologic response ina very high percentage of patients.

Because of organ preservation chemoradiotherapy is the first line treatment for anal cancer and surgical resection is reserved for salvage treatment for residual or recurrent disease.

The standard of care for locally advanced anal cancer is definitive pelvic chemoradiotherapy.

In the metastatic setting chemotherapy is considered standard of care however the addition pelvic radiotherapy in the metastatic setting prolongs survival (Wang Y).

XELOX-XRT In a phase 2 study showed complete response rate of 100% and a 89.5% three years time to treatment failure.

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