Anal cancer and Anal warts
The anus, which is also known as the “anal canal” is the tube connecting the lower end of the rectum with the outside of the body to allow the excretion of faeces. It is about 3 cm long and is surrounded by muscles - known as the anal sphincter- to keep it tightly closed most of the time.
Anal cancers arise from the types of cells lining the anal canal, known as "squamous cell carcinomas”. Cells that are becoming malignant but have not yet broken through the surface layer are referred to as "anal intraepithelial neoplasia (AIN)", "high grade dysplasia", "Bowens Disease" or "carcinoma in-situ".
Anal cancer is very rare and affects a slightly more women than men. The main risk factor for anal cancer is infection from the human papilloma virus (HPV). Other factors include smoking and impaired immunity from causes such as HIV or immune suppressing drugs following organ transplant. The risk of contracting the disease increases with age.
How Anal Cancer is Investigated
When you are seen in clinic the consultant will take a full history and carry out a clinical examination. Usually this will involve a rigid sigmoidoscopy and sometimes a proctoscopy as well.
An examination under anaesthetic with a biopsy is usually required to confirm the diagnosis.
A CT scan and an MRI scan are usually performed to fully assess the disease.
Sometimes a PET scan may be required if there are Concerns about the spread of the disease.
Anal Cancer Treatment
If the cancer is diagnosed in its early stages as a very small lump on the edge of the anus, surgical excision alone can also be an effective treatment for anal cancer without causing any significant damage to the anal sphincter muscles.
The most common treatment given for anal cancer is a combination of chemotherapy and radiotherapy (known as synchronous chemoradiotherapy).
If an anal cancer is particularly large a colostomy may be required before starting chemoradiotherapy treatment.
In some cases, this can be reversed after the treatment has been completed.
If the chemoradiotherapy is not successful in eradicating the cancer, surgery may be required. The type of surgery needed depends upon the type and size of the cancer, and whether it has spread to other parts of the body. This will often require surgery to remove the whole anus and will result in a permanent colostomy.
Because anal cancer is rare the treatment has been concentrated to recognized highly specialist teams.