Anal cancer diagnosis
When anal cancer is suspected (due to symptoms of the condition) diagnosis is made with the help of physical, pathological and laboratory tests along with imaging studies. Diagnosis of anal cancer includes:-
- Digital rectal examination - this is performed by the surgeon who inserts a gloved and finger gently into the anus and feels for the lumps. Women may also have an internal examination of their vagina to detect any lumps in the anus.
- Biopsy of the lump – a small sample of tissue is taken from the tumour. It is then fixed onto a slide and examined under the microscope after staining with appropriate dyes. A biopsy may be done under local or general anaesthetic. The cellular appearance may help detect anal cancer with a higher degree of confirmation.
- Imaging studies - CT (computerised tomography) scan is prescribed to detect spread and exact extent of the cancer. An MRI (magnetic resonance imaging) scan is a more detailed imaging study. An MRI of the whole abdomen is advised to check for spread and other focus/foci of cancer. A PET-CT scan or an Endoanal ultrasound scan may also be used to detect the activity of the cancer cells in different parts of the body as well as to delineate the cancer.
- Staging and grading of anal cancer – once the laboratory and imaging studies are performed, the cancer is staged and graded.
A low grade cancer means that the cancer cells look very much like normal cells and are thus slow growing and less aggressive. High grade cancer cells are very different from normal cells and are thus aggressive and fast growing. These are more likely to spread.
The stage of a cancer describes its size and whether it has spread beyond its original site. This helps in deciding on the most appropriate treatment and predicts the outcome or prognosis.
Stage 1 cancer only affects the anus and is smaller than 2cm (¾in) in size. It has not begun to spread into the sphincter muscle.
Stage 2 cancer is bigger than 2cm (¾in) in size, but has not yet spread into nearby lymph nodes or to other parts of the body.
In Stage 3 cancer there is spread to the lymph nodes near the rectum, or to nearby organs such as the bladder or vagina or to lymph nodes in the groin and pelvis.
In Stage 4 anal cancer, the cancer has spread to lymph nodes in the abdomen or to other parts of the body, such as the liver.
Anal cancer treatment
Anal cancer is usually treated by a multidisciplinary team. This includes:
- a cancer surgeon
- a gastroenterologist
- a radiotherapist
- a pathologist
- an oncologist
- a diet consultant
- a cancer nurse or a specialist nurse
- a social worker
- a behavioral therapist
The main type of treatment for anal cancer is a combination of both radiation therapy and chemotherapy. The two treatments are normally given at the same time. This is called chemoradiation. Combined treatment is usually very successful. For small tumors surgery may be useful.
For radiation therapy high-energy x-rays are used to destroy the cancer cells. These beams are directed at the cancer from outside the body using a large X ray like machine.
For this the patient needs to visit the facility frequently. The treatment is often given for a few minutes each weekday for 4-6 weeks. This is called external radiotherapy.
Common side effects of radiation therapy include:
- excessive flatus and bloating
- skin rashes and burns around the area of radiation
- hair loss
- vaginal and anal dryness
- premature menopause etc.
For chemotherapy, anti cancer drugs are used to kill the cancer cells. Drugs commonly used to treat anal cancer include mitomycin, capecitabine and fluorouracil (5FU).
Chemotherapy can cause several side effects including:-
- propensity for infections due to low white blood cell counts
- bleeding risks due to low platelet counts
- hair loss
- loss of appetite
- mouth ulcers etc.
Surgery is useful for small anal cancers. Types of surgery include local resection of the tumor. The operation only removes the area of the anus containing the cancer cells. The anal sphincter is spared and the bowel function remains normal.
A more extensive surgery is the abdominoperineal resection where both the anus and rectum are removed. The operation requires a permanent colostomy that helps drain the feces from an artificial opening.