Anal cancer is a cancer (malignant tumor) that comes from the anus and the distant opening of the digestive system. A separate entity of colorectal cancer is more common. Anal cancer is usually an anal squamous cell carcinoma that occurs near squamocolumnar junction and is often associated with human papillomavirus (HPV) infection. It can be keratinizing or non-keratinizing (Candida). Other types of anal cancer are adenocarcinoma, lymphoma, and sarcoma or skin cancer. According to the data collected from 2004 to 2010, the five-year survival rate in the United States is 65.5%, although individual rates may vary depending on the stage of the cancer at the time of diagnosis and response to treatment.
Symptoms of anal cancer may include pain or pressure in the anus or rectum, changes in bowel habits, bumps near the anus, rectal bleeding, itching, or discharge. The bleeding can be severe.
b. Risk factors
- HPV: Examination of tumor tissue for squamous cell carcinoma in patients in Denmark and Sweden showed a high proportion of cancers positive for anal HPV types, which is also associated with an increased risk of cervical cancer. In another study, high-risk HPV types, including HPV-16, were detected in 84% of the anal cancer samples examined. According to the study in Denmark and Sweden, it is estimated that 90% of anal cancers are attributable to HPV.
- Sexual activity: Having multiple sexual partners increases the risk of exposure to HPV. Intimate sex, either male or female, increases the risk of anal cancer in seven due to HPV. People who have anal intercourse with several partners are 17 times more likely to have anal cancer than those who do not.
- Smoking: Current smokers are more likely to develop anal cancer than non-smokers. Epidemiologist Janet Daling, PhD in the Department of Public Health Sciences of Fred Hutchinson and her team discovered that smoking plays an important role in the development of anal cancer, independently of other factors. Like sexual activity. More than half of the anal cancer patients were current smoking masters at the time of diagnosis, compared to the smoking rate, around 23% among the controls. “Current smoking is an important advocate of this disease,” Daling said. “If you are a current smoker, multiply by the risk of every four, if you are a man or a woman.” They indicated that the underlying mechanism behind smoking and the development of anal cancer is not known, but researchers think that smoking interferes with a process called apoptosis, or the death of programmed cells, which help To eliminate abnormal cells that can turn into cancer from the body Another possibility is that smoking inhibits the immune system, which can reduce the body’s ability to eliminate infections persistent or abnormal cells.