Everything about Anal Cancer totally explained
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.
Risk factors
- Human papillomavirus (HPV) infection: An examination of squamous cell carcinoma tumor tissues from patients in Denmark and Sweden showed a high proportion of anal cancers to be positive for the types of HPV that are also associated with high risk of cervical cancer (90% of the tumors from women, 100% of the tumors from homosexual men, and 58% of tumors from heterosexual men). In another study done, high-risk types of HPV, notably HPV-16, were detected in 84 percent of anal cancer specimens examined.
- Sexual activity: Having multiple sex partners or having anal sex, due to the increased risk of exposure to the HPV virus.
- Smoking: Current smokers are several times more likely to develop anal cancer compared with nonsmokers.
- Immunosuppression, which is often associated with HIV infection.
- Benign anal lesions. (inflammatory bowel disease (IBD), hemorrhoids, fistulae or cicatrices) Inflammation resulting from benign anal lesions, such as hemorrhoids and anal fistulas, has been considered to cause a predisposition to anal cancer
Prevention
Since many, if not most, anal cancers derive from
Human Papilloma Virus infections, and since the
HPV vaccine prevents infection by several strains of the virus, scientists surmise that HPV vaccination will prevent anal cancer.
Screening
Anal
pap smears similar to those used in
cervical cancer screening have been studied experimentally for early detection of anal cancer in high-risk individuals.
Treatment
Localized disease
Anal cancer is most effectively treated with surgery, and in early stage disease (for example, localized cancer of the anus without
metastasis to the
inguinal lymph nodes), surgery is often curative. The difficulty with surgery has been the necessity of removing the
anal sphincter, with concomitant fecal
incontinence. For this reason, many patients with anal cancer have required permanent
colostomies.
In more recent years, physicians have employed a combination strategy including
chemotherapy and
radiation treatments to reduce the necessity of debilitating surgery. This "combined modality" approach has led to the increased preservation of an intact anal sphincter, and therefore improved quality of life after definitive treatment. Survival and cure rates are excellent, and many patients are left with a functional sphincter. Some patients have fecal incontinence after combined
chemotherapy and radiation. Biopsies to document disease regression after
chemotherapy and radiation were commonly advised, but are not as frequent any longer. Current
chemotherapy active in anal cancer includes
cisplatin and
5-FU;
mitomycin has also been used, but is associated with increased toxicity.
Metastatic or recurrent disease
Up to 10% of patients treated for anal cancer will develop distant metastatic disease. Metastatic or recurrent anal cancer is difficult to treat, and usually requires
chemotherapy. Radiation is also employed to
palliate specific locations of disease that may be causing symptoms. Chemotherapy commonly used is similar to other
squamous cell epithelial neoplasms, such as
platinum analogues,
anthracyclines such as
doxorubicin, and antimetabolites such as
5-FU and
capecitabine.
Prognosis
Further Information
Get more info on 'Anal Cancer'.
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