What is Anal Canal Cancer
Anal canal cancer is a rare type of cancer that develops in the anal canal and the outer edges of the anus. This canal is a small tube located at the end of the rectum, through which stool exits the body.
Anal cancer forms when a genetic mutation causes normal, healthy cells to become abnormal. Healthy cells grow, multiply, and die in a controlled way. Abnormal cells, however, grow and multiply uncontrollably, forming a cancerous tumor.
The accumulation of these abnormal cells forms a mass called a tumor. Cancer cells can invade nearby tissues and can also break away from the initial tumor, spreading to other parts of the body in a process called metastasis.
Anal cancer is closely related to a sexually transmitted infection called human papillomavirus or HPV: HPV evidence is detected in most anal cancers. In this context, HPV is considered the most common cause of anal cancer.
Malignant tumors arise in different types of tissues, with squamous cell carcinoma accounting for 85% of anal canal tumors.
Anal cancer is rare and accounts for 1% to 2% of all colorectal tumors. Due to its low incidence, the INCA (National Cancer Institute) does not provide statistics for new cases. According to the Cancer Mortality Atlas for 2018, there were 603 deaths (210 men and 393 women) due to this neoplasm.
Symptoms of anal canal cancer
Anal canal cancer can cause signs and symptoms such as rectal bleeding and anal pain.
Changes in bowel habits and presence of blood in the stool are warning signs to seek medical advice.
The most commonly observed symptom is bright red rectal bleeding during bowel movements, often associated with pain in the anal area. Other signs that are noteworthy include itching, burning, unusual discharge, sores in the anal region, and fecal incontinence (inability to control bowel movements).
Diagnosis of anal canal cancer
The first step in diagnosing anal canal cancer involves a digital rectal exam and, if necessary, an anoscopy and/or a proctoscopy. In these exams, the doctor inserts a small speculum into the anus to look for abnormalities or uses a proctoscope, which is a short, straight, rigid, hollow metal tube that typically has a small light mounted at the end.
If deemed necessary, the specialist may request a biopsy of a tissue sample to confirm the diagnosis.
Other tests, such as magnetic resonance imaging, may be requested to assess the extent of the tumor and help choose the best treatment.
Treatment for anal canal cancer
In the ast, surgery was the only treatment available to cure anal canal cancer, but it often resulted in a permanent colostomy in most cases.
Currently, most people are treated with a combination of chemotherapy and radiation therapy, known as chemoradiotherapy. Although this approach avoids the need for a colostomy in most cases and increases the chances of a cure, it can also increase side effects. Therefore, it is important to discuss all possibilities with your doctor and address any concerns.
The combined approach often eliminates the need for surgery, but depending on the stage of anal canal cancer, surgery may be indicated.
Prevention of anal canal cancer
Some infections, such as those caused by HPV and human immunodeficiency virus (HIV), are identified as responsible for the increased incidence of anal tumors.
Other sexually transmitted diseases, such as condylomata, gonorrhea, genital herpes, and chlamydia, as well as anal sex, smoking, and chronic anal fistula (an abnormal connection between the surface of the anal canal and the tissue around the anus, with purulent discharge), are related to the development of this type of cancer. Therefore, some prevention methods include:
- Use a condom (condom) in all sexual relations;
- If possible, get the HPV vaccine;
- Quit smoking;
- Avoid anal sex;
- Pay attention to hygiene conditions and signs of chronic irritation of the anus.
