Anal cancer is a type of cancer which arises from the anus, the distal orifice of the gastrointestinal tract. It is a distinct entity from the more common colorectal cancer.
The etiology, risk factors, clinical progression, staging, and treatment are all different.
Anal cancer is typically a squamous cell carcinoma that arises near the squamocolumnar junction.
The American Cancer Society estimates that in 2009 about 5,290 new cases
of anal cancer will be diagnosed in the United States (about 3,000 in
women and 2,000 in men).
Symptoms of anal cancer include bloating and change in bowel habits, a
lump near the anus, rectal bleeding, itching or discharge. Women may
experience lower back pain due to pressure the tumor exerts on the
vagina, and vaginal dryness.
Anal Pap smears similar to those used in cervical cancer screening have
been studied for early detection of anal cancer in high-risk
individuals.
Since many, if not most, anal cancers derive from human papillomavirus
infections, and since the HPV vaccine prevents infection by some strains
of the virus and has been shown to reduce the incidence of potentially
precancerous lesions, scientists surmise that HPV vaccination may reduce
the incidence of anal cancer.
Further Reading
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"Anal cancer"
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