Anal cancer is a rare type of cancer that forms in the tissues of the anus or anal canal. About 80% of anal cancers are diagnosed in individuals who are over age 60. Before age 35, anal cancers are common among men; however, after age 50, it is more commonly seen among women.
Anal cancers are different from colorectal cancers, which are relatively more common. Human papillomavirus (HPV) infection in the anal canal, which may lead to genital warts, is considered to be a major risk factor for anal cancer development. Receptive anal intercourse is also strongly linked to anal cancer incidence.
Also, immunocompromised patients, i.e., those with HIV and other diseases, show a higher risk of developing anal cancer with a poor prognosis.
Often, the first sign of anal cancer is bleeding. Another common symptom is the itching at the anal opening; however, individuals tend to attribute this symptom to haemorrhoids. This may lead to a delayed diagnosis of anal cancer. Following are other symptoms that are associated with anal cancer:
- Unusual discharges from the anus
- Lump in the anal region
- Pressure in the anal area
- Change in bowel habits
The exact cause of anal cancer is unknown. Nevertheless, a few risk factors have been identified for anal cancers.
Anal cancer is closely associated with the sexually transmitted infection caused by human papillomavirus (HPV). Chronic HPV infection is considered to be the biggest risk factor for anal cancers.
Following are various other risk factors that are associated with anal cancer development:
- Age: The risk of developing anal cancer increases with age.
- Anal Intercourse: Anal intercourse increases the risk of anal cancer development.
- Multiple Sexual Partners: Having multiple sexual partners contributes increased risk of developing anal cancer.
- Smoking: Smoking is associated with an increased risk of anal cancer.
- History of Genital Cancers: Those with a history of cervical cancer, vulvar cancer or vaginal cancer tend to have a higher risk of developing anal cancer.
- Immunosuppressor Drugs or Conditions that Suppress Immunity: Those on immunosuppressants and those with immunocompromised conditions, such as HIV infection, have a higher risk of developing anal cancer.
There are various tests available to detect and diagnose anal cancer:
a. Anal Canal and Rectum Examination: During this procedure, the doctor inserts a gloved, lubricated finger into the rectum to look for any abnormal growths.
b. Visual Inspection of the Anal Canal and Rectum: An anoscope, a short, lighted tube, is inserted into the anal canal and rectum to find any abnormalities.
c. Ultrasound: Ultrasound scan of the anal canal helps in tumour detection, determining tumour size along with the depth of invasion. During the procedure, a probe is inserted into the anal canal and rectum, which emits high-energy sound waves that are captured and converted to images. These images will provide information on any abnormalities present.
d. Biopsy: If any abnormality is found, a small sample of tissue may be excised and sent to a laboratory for further examination.
Once the above tests confirm the diagnosis, the doctor may recommend additional tests for cancer staging. These tests help in finding out if cancer has spread to lymph nodes and other critical organs in the body.
PET/CT scan and MRI scan are the commonly recommended tests for staging purposes.
Before devising treatment plans for anal cancers, multiple factors such as the stage of the disease, the tumour grade, the patient’s age, the overall condition of the patient and their preferences are taken into account. Various treatment options available for anal cancer include radiation therapy, chemotherapy and surgery. It has been found that the multimodal approach will have a positive impact on the treatment response and clinical outcomes among anal cancer patients.
a. Radiation Therapy: During radiation therapy, high-energy radiation beams are delivered to the tumour to kill the cancer cells. This treatment destroys the DNA structure in cancer cells and thereby kills them. Radiation can be delivered using an external radiation source (linear accelerators) or an internal radiation source (brachytherapy). Radiotherapy planning is done based on the stage, size and the exact location of the tumour.
b. Chemotherapy: During chemotherapy, potent chemo drugs are administered into the body to kill or destroy cancer cells throughout the body. Chemotherapy can be administered orally, intravenously or intramuscularly. As a systemic therapy, it destroys or stops the cancer cells from dividing throughout the body. Among anal cancer patients, chemotherapy is administered in different situations:
- Right before the Surgery (Neoadjuvant Chemotherapy): Before the surgery, chemotherapy is combined with radiation (chemoradiation) and administered. This is often the first line of treatment among anal cancer patients. In most cases, this approach eliminates the need for surgery.
- Right after the Surgery (Adjuvant Chemotherapy): In a few cases, chemoradiation is administered after the surgery in order to ensure that there are no residual cancer cells left. Adjuvant chemotherapy reduces the risk of a relapse.
- To Manage Relapse: In case anal cancer has returned, the doctor may recommend chemotherapy. It may or may not be combined with surgery.
- As Palliative Support: If the cancer is in the advanced stage and has spread to other organs, such as kidneys, liver and lungs, chemotherapy is recommended to control the growth and relieve the symptoms and discomfort caused.
c. Surgery: Although not the main line of treatment for anal cancer, surgery is considered in a few cases based on the stage of the disease.
- In Early-stage Cancer Cases: In the early stages, when the tumour size is small, the doctor may recommend surgery to treat it. During the procedure, the doctor operates the tumour along with a small amount of healthy tissue around it. The doctors take extra care to not damage the anal sphincter muscles that surround the anal canal and control the bowel movements. Depending on the stage of the disease, chemotherapy or radiation therapy may also be recommended along with the surgery.
- In Advanced-stage Cancer Cases or When There is Poor Response to Other Treatments: In certain cases, where patients show no response to chemotherapy or radiation therapy or are in advanced stages, doctors may recommend a far more extensive surgical procedure called an abdominoperineal resection (AP resection). During this procedure, the surgeon removes the anal canal along with the rectum and a small portion of the colon. Later, the remaining portion of the colon is attached to an opening (stoma) in the abdomen, through which the waste leaves the body and gets collected in a colostomy bag.
It is important to note that early detection improves the chances of positive clinical outcomes among patients and supports a better quality of life.
Frequently Asked Questions
1. What happens if I leave anal cancer untreated?
An untreated anal cancer progresses to advanced conditions and spreads to other critical organs. This causes many health complications and may lead to poor survival rates.
Early detection, therefore, plays a significant role in cancer management. It is important to not ignore any symptoms and take appropriate actions whenever necessary.
2. Can I prevent anal cancer?
There are many measures that can reduce your anal cancer risk. Some of the measures include practising safe sex habits, receiving HPV vaccination, quitting tobacco and cultivating a healthier lifestyle.
3. What are the side effects associated with anal cancer treatments?
Side effects vary from patient to patient. Some may experience very mild side effects, while some may experience moderate to severe side effects.
The potential side effects associated with anal cancer treatment include diarrhoea, anal irritation and pain, hampered bowel movements, discomfort during bowel movements, tiredness, nausea, constipation, skin changes, low blood cell count, loss of appetite, hair loss, etc.
4. How do I know if I have haemorrhoids or cancer?
In many cases, haemorrhoids and cancer show the same symptoms, due to which the patients tend to ignore the symptoms. This may eventually lead to delayed diagnosis and poor clinical outcomes.
Rectal pain, itching and bleeding are the main signs of anal cancer, and they are not to be ignored.
In general, any abnormalities associated with your health should be presented to your doctor immediately, as this supports early detection and timely treatment for any health issues.