Anal cancer is a cancer that affects the tissues of the anus. Most anal cancers are squamous cell cancers. Squamous cells are a type of cell that line the surface of the anal canal.
Rarer types of anal cancer include basal cell carcinoma, melanoma and adenocarcinoma of the anus, a cancer of the cells that make the mucus that helps the stools (faeces) move smoothly out of the anus.
Anal cancer symptoms
The symptoms can include:
- bleeding from the rectum
- lumps around the anus or in the groin
- pain or discomfort
- discharge of mucus from the anus
- difficulty controlling your bowel movements.
Although some of these symptoms may be related to other medical conditions, you should talk to your GP if you have any of these symptoms.
Causes of anal cancer
It is unknown what causes anal cancer, however there are known risk factors, including:
- human papilloma virus (HPV) and other diseases including chlamydia, genital warts and AIDS/HIV
- women who have already had cervical, vulval or vaginal cancer or a history of abnormal cells in the cervix, vulva or vagina
- people with weakened immune systems
Screening for anal cancer
There is currently no screening for anal cancer available.
Diagnosis for anal cancer
If your doctor suspects you may have anal cancer, you will have one or more of the following tests:
You may have a blood test to see if your red blood cells are low (anaemia). You may also have blood tests to check your liver and kidney function.
Examination and biopsy
A doctor will conduct an examination and biopsy of your rectum. This procedure, called a proctoscopy or sigmoidoscopy, involves having a long tube with a light inserted into the rectum. Your bowel is inflated with some air to allow the doctor to see more clearly.
A tissue sample (biopsy) is then taken to examine under a microscope for cancer cells. This procedure is usually done as an outpatient. It can be done under general anaesthetic, particularly if more tissue samples are being taken for staging of the cancer.
If anal cancer is detected, you may have scans to see if the cancer has spread to other parts of your body. These may include:
A magnetic resonance imaging (MRI) scan uses a powerful magnet and radio waves to create 3D pictures of areas inside the body. Sometimes dye will be injected into a vein to make the pictures clearer.
An ultrasound probe is inserted through the anus into your rectum. This can be uncomfortable but is usually not painful. The probe sends out soundwaves that echo when they meet something dense, like a tumour, and images are projected onto a computer screen.
A computerised tomography (CT) scan uses x-rays and a computer to create a detailed picture of an area inside the body. Before the scan, dye may be injected into a vein to make the pictures clearer.
This positron emission tomography (PET) scan involves a low-level injection of a radioactive drug, fluorodeoxyglucose (FDG). The FDG shows up areas of abnormal tissue.
Treatment for anal cancer
Most people with anal cancer receive a combination of chemotherapy and radiotherapy treatments at the same time, called chemoradiation. Surgery may also be used. This will depend on the type and stage of anal cancer you have.
Radiotherapy, the use of x-rays to kill or injure cancer cells, is given either externally, where a machine directs radiation at the cancer and surrounding tissue; or from inside the body (brachytherapy), where radioactive material is put in thin tubes and placed near the cancer internally.
Radiotherapy to this area of the body may cause temporary or permanent infertility in both men and women. Therefore, if you are concerned about how treatment will affect your fertility, it is important to raise your concerns with your treatment team before treatment commences.
Chemotherapy can be used alone or combined with radiotherapy to treat anal cancer. It is usually given as a drug that is injected into a vein (intravenously).
For chemoradiation treatment, radiotherapy starts the same day as the first cycle of chemotherapy commences. Radiotherapy is delivered every week day for about 5 to 6 weeks. Side effects have been greatly reduced since the introduction a focused radiotherapy called intensity modulated RT (IMRT).
Surgery may be used to treat anal cancer if it is in the early states, or hasn’t completely gone after chemoradiation, or it comes back after treatment (recurs). The type of surgery will depend on the size and type of the cancer. An early stage tumour that doesn’t affect the muscles around the anus may be operable as a local resection, where the affected area is removed.
A larger operation, called an abdomino-perineal resection, may be required if the cancer is present after initial treatment. This procedure involves the removal of the anus, rectum and part of the colon, and possibly lymph nodes near the anus and groin. If you have this procedure, you will have a permanent stoma (colostomy). Before and after your surgery, a stoma nurse will assist you in what is involved in living with a colostomy.
Although it is most often used by people with advanced cancer, palliative treatment can be used at any stage of cancer treatment. It is intended to improve a person’s quality of life by alleviating the symptoms of cancer, without trying to cure the disease. It can include pain relief, and the management of other physical and emotional symptoms.
Depending on your treatment, your treatment team may consist of a number of different specialist staff, such as:
- GP – works with specialists in your treatment team and explains information they provide
- a radiation oncologist, who prescribes and coordinates radiotherapy treatment
- a medical oncologist, who prescribes and coordinates the course of chemotherapy
- gynaecologist – diagnoses and treats diseases of the female reproductive organs and may be consulted if cancer has spread to the genitals
- a colon and rectal surgeon
- a cancer nurse
- a stoma nurse
- sexual therapist – a qualified counsellor who has been trained to help patients manage sexual concerns
- other allied health professionals, such as dieticians, physiotherapists and pyschologists.
Prognosis for anal cancer
It is not possible for a doctor to predict the exact course of a disease, as it will depend on each person’s individual circumstances. However, your doctor may give you a prognosis, the likely outcome of the disease, based on the type of anal cancer you have, the test results, the rate of tumour growth, as well as your age, fitness and medical history.
The most common types of anal cancer have very good long-term prognosis, especially if the cancer is found early.
Preventing anal cancer
As there is no known cause for anal cancer, it is not possible to prevent most cases of this disease.
However, it is possible to reduce some of the risks, in particular HPV infection by using one of the HPV vaccines that are now available.