Anal cancer occurs around the opening of the anus, or in the area below where the anal canal and rectum meet. The majority of anal cancers are lymphoblastic carcinomas, which originate from superficial skin cells. A small proportion are cloacal carcinomas, which originate mainly from the mucosal cells of the upper part of the anal canal. Although there are other types of cancer that occur in this area, these two are the more common types. Their clinical manifestations and treatment modalities are also largely similar. When there is a malignant tumor on the surface of the anal region, but it does not invade deep tissue structures, this state is called Bowen’s disease. Is anal cancer common? Anal cancer is actually rare. It accounts for only two percent of all cancers of the digestive tract. Approximately 3,400 patients are diagnosed with anal cancer in the United States each year, and about 500 people die from anal cancer. Comparatively, about 140,000 new cases of rectal cancer are diagnosed in the United States each year, and about 50,000 deaths from rectal cancer occur each year. What are the risk factors for anal cancer? We cannot determine the exact cause of anal cancer, but we do know that certain risk factors are associated with anal cancer. As the risk factors increase, the chance of developing anal cancer increases significantly. Age: Middle-aged people over 50 years old. Anal warts: Patients who have been infected with human papillomavirus causing warts have a much higher chance of getting anal cancer. 2.Anal intercourse: People who engage in anal intercourse are also at risk for anal cancer. 3.Incomplete immune system: Incomplete immune system, such as patients who received transplantation, must take immunosuppressive drugs to suppress the normal immune system. AIDS patients are also a risk group for anal cancer. 4.Patients with long-term anal inflammation: Patients with long-term anal fistula or open wounds also have certain risk factors. 5.Pelvic radiation therapy: Patients who have to receive pelvic radiation therapy because of rectal cancer, prostate cancer, bladder and uterine cancer. Can anal cancer be prevented? Very few tumors can be completely prevented, but by reducing risk factors and close follow-up, the occurrence of cancer will be greatly reduced. Avoid anal sex and HIV and HPV infection, and use condoms in all sexual encounters. Although condoms cannot completely eliminate all infectious agents, they reduce many of the contributing factors. Stopping smoking will reduce the incidence of anal cancer as well as other types of cancer. What are the physical signs of anal cancer? Anal cancer can be detected very early and is the easiest part of the digestive tract to palpate and visualize. Signs of anal cancer include: 1) bleeding at the anal opening; 2) foreign body sensation at the anal opening; 3) pain in the anal area; 4) persistent or recurrent anal itching; 5) change in stool habit and thin stool shape; 6) discharge from the anal opening; 7) swelling of lymph nodes in the inguinal region of the anus. These symptoms may also appear in diseases such as hemorrhoids, and it is possible that you may ignore it. It is best to consult your physician as soon as you have these symptoms appear.