Anal cancer is a disease that starts when cells in the anus (on the anus) change and start growing out of control. When normal cells change into abnormal and start growing out of control, it will result into development of mass called tumor.
Tumor can either be malignant or benign. Benign tumor is the one that is still enclosed and cannot spread to other parts of the body while malignant is the one that can spread to other parts of the body.
To understand well anal cancer, it is important for one to have knowledge on anus. About anus Anus is an opening at the lower end of large intestine through which the waste matter (feces/stool) leaves the body. It is just below rectum in which waste matter are temporarily stored before being removed from the body. Between anal opening and rectum there is anal canalthrough which these two are connected. The canal is few centimeters long andit goes from the rectum to the outside skin at the anus (anal verge). In the anus there are muscles called sphincters (internal and external sphincter muscles) that help control of the removal of waste matter from the body and prevent waste matter from coming out without control. During bowel motion, the muscles of the anus (sphincters) relax to release the solid waste matters (feces or stools).
1. Squamous cell carcinoma. Most anal cancers are squamous cell carcinomas(SCCs), which come from the flat (squamous) cellsthat line much of the anus.
2. Adenocarcinoma. These are anal cancers that develop from glandular cells that produce mucus that lubricate the anus for easily removal of waste product. These glandular cells are located under the anal lining (mucosa).
3. Cloacogenic carcinoma. These arise from the cells similar to squamous cells. These are located in the transitional zone called cloaca (between lower part of the rectum and outer part of anus). Although under microscope they appear slightly different from squamous cells carcinoma but they behave and are treated like squamous cell carcinoma.
4.Basal cell carcinoma. This is type of skin cancer that develop from the basal cells of anal skin.
5. Melanoma. These develop from cells that produce color of the anal skin.
Risk factors of anal cancerWhen dealing with cancer, anything that increases your probability of developing cancer is called a risk factor. Risk factors only influence development of cancer but it does not directly cause cancer. Sometimes people with risk factors do not develop the disease while those with no risk factors do develop the disease. Having knowledge on risk factors will help you live your life making some better healthy choices to reduce the risk. The risk factors of anal cancer include the following.
1. Age Anal cancer is more common to older people than to the young.
2. Human papilloma virus (HPV) infection. This is the virus that is transmitted through sexual practices. There are many types (strains) of these HPV viruses. Studies indicate that, some strains of this virus lead to development of anal cancer.
3. Having weakened immune system. Weak immune system will increase the risk of a person to develop anal cancer as their immune system cannot fight infections including the ones that could lead to development of anal cancer like HPV infections. These people include those with HIV/AIDS and those using immunosuppressive drugs.
4.Cigarette smoking. Chemicals from cigarette smoke can cause harm at any part of the body as they carries in the blood. Smokers are at an increased risk of developing anal cancer than non-smokers.
5. Having anal sex or multiple sexual partners. This will increase the chance of contacting HPV virus hence the risk of developing anal cancer.
6. Having a history of cervical, vaginal or vulva cancer. These are said to be at more risk of developing anal cancer than those with no history.
7. Anal warts. This is not cancer or a condition that might change into cancer but it is anal infection that is caused by some other strains of HPV that do not cause anal cancer (low risk HPV). Although anal warts are unlikely to change into anal cancer, but since these people have been prone to infection with low risk Human papilloma viruses, their risk of being infected by high risk HPV is also high.
Prevention of anal cancerTo prevent something you need first to know what causes it. Since the specific cause of anal cancer is still unknown, currently there is no proven way of completely preventing someone from developing this disease but there are some ways that may help reduce the risk of developing it, including the following;
> Taking vaccination against human papilloma virus.
> Stop or avoid cigarette smoking..
> Avoid anal sexual intercourse.
Avoid having multiple sexual partners.
> Use condom. Condoms can help protect you from contacting HIV although they cannot fully protect you from HPV
Early detection and screening of anal cancerWhen it comes to cancer, early detection normally provide better treatment outcome. When anal cancer is found early, chances for better treatment outcome are very high. For most cancers, early detection has been greatly contributed by the presence of screening processes. Screening is the process of running some tests to someone with no symptoms of the disease with the intention of determining presence or absence of the disease. Unfortunately, currently there is no widely recommended screening tests for anal cancer in Tanzania. For those at higher risk of developing anal cancer like those with the history of cervical, vaginal and vulva cancer, men who are homosexuals and those who are HIV positive, it is recommended that they have regular digital rectal examinations (DRE) and pap tests. DRE involve a doctor inserting a gloved, lubricated finger into the anus to feel the unusual growths and lumps. It is also used in examination of prostate gland in men. Pap test involve swabbing anal lining and examining the cells under microscope. If these examinations shows any abnormalities, more tests will be recommended.
Signs and symptoms of anal cancerPeople with anal cancer tend to experience some of the following symptoms. Sometimes those signs and symptoms may be as result of other medical conditions that are different from cancer. Therefore, seeing a doctor upon experiencing any of the symptoms is advised. The signs and symptoms of anal cancer include the following;
> Blood in stools (feces) or on toilet paper.
> Itching, pain or discomfort around the anus.
> Discharge of mucus from the anus.
> A lump near the edge of the anus.
> Ulcers around the anus.
> Loss of bowel control.
Diagnosis of anal cancer
Cancer diagnosisMedical diagnosis simply means identification of nature of an illness by elimination of the symptoms. Normally people don`t go to hospital knowing they have cancer but during diagnostic procedures is when doctors detect the disease.
Following suspicion of the disease, doctors normally run combination of tests to determine whether there are cancerous cells in the body or not and if there are cancer cells, how far have they spread. Along with thorough medical history and physical examination, doctors normally use combination of the following tests to diagnose cancer.
Laboratory tests. Laboratory tests are important in ruling out other conditions and confirming diagnosis. For cancer diagnosis laboratory tests normally include blood tests, urine tests, tumor markers and other body fluids tests.
Blood tests. Blood tests help to reveal level of different substances in the blood which will help doctors to know if there is anything wrong in the body. From blood tests doctors can see complete blood count which indicates number, size and maturity of blood cells. Also from the blood tests doctors can analyze if kidney and liver are working properly.
Urine tests. Urine tests (urinalysis) involve laboratory examination of urine to check presence of blood, proteins, and other substances such as drugs. For instance blood in the urine may be an indication of benign condition, infection or other health problem.
Tumor markers. These are biomarkers (proteins) that can be produced by both cancer cells and normal body cells in response to cancer. Tumor markers are released into the blood or urine. Although studies are still conducted to determine role of these markers in diagnosing cancer because sometimes people with benign condition will have elevated level of these proteins. Also not all tumors have their markers and some markers are not specific to one type of tumor.
Other body fluids. Despite being rarely used, sometimes body fluids can be tested in the lab during diagnosis of cancer. For instance the use of cerebral spinal fluid (CSF) and pleural fluid. CSF is used in diagnosis of brain tumors while pleural fluid for lung cancer.
Diagnostic imaging. Diagnostic imagings involve tests that create pictures of inside the body that help the doctor to see if there is tumor or not. There are several imaging tests used in cancer diagnosis depending on the type and location of cancer suspected. These imaging tests include;
Computed tomography (CT) scan. CT scan machine is a donut-shaped scanner that uses x-rays to create series of pictures of body organs from different angles. This machine is linked to a computer where those series of pictures taken will be combined to create a 3D- image of inside the body. During the scanning process patient will lie still on the table which will slide into the scanner. In order to get a clear image, sometimes the doctor will inject the patient with a contrast material before scanning. From the images the doctor will be able to differentiate between healthy and unhealthy tissues.
Magnetic resonance imaging (MRI). MRI is an imaging technique that uses powerful magnet and radio waves to take series of pictures of body organs and create a 3D image in a computer linked to a machine. Just like in CT, during MRI procedure the patient will lie on a table that will slide into a long round chamber. Also during this procedure the doctor may inject the patient with a contrast material for clear image view.
X-ray. This is an imaging technique that is uses low dose of radiation to create pictures of inside your body. Technician will position the patient and direct the x-ray beam to the intended part of the body.
Ultrasound. Ultrasound is a diagnostic imaging procedure that uses high energy sound waves to produce images of organs inside the body. During the examination, a patient will lie on the table while the technician will slowly move a device called transducer on the skin over the part of the body that is being examined.
PET scan. Positron emission tomography (PET) scan is an imaging test that uses radioactive glucose to create 3-D images of areas inside the body. Radioactive glucose is used for this test because cancer cells tend to absorb more glucose than normal body cells, so the scan will show which areas of the body has more glucose than others. Before the scan, doctor will inject the patient with tracer called radioactive glucose then during imaging the patient will be asked to lie on the table that will be moving back and forth through the scanner.
Bone scan. Bone scan is used to examine bones. When it comes to cancer, bone scan is used for diagnosis of bone cancer or cancer that has metastasized into the bones. Before the test, patient will be injected with small amount of radioactive material that tends to collect more on abnormal parts of the bones. Then pictures that will be taken by a scan will indicate the distribution of those radioactive materials in the bones throughout the body.
Biopsy. Biopsy is a diagnostic procedure that involves removing a tissue sample from the body and examines it under microscope in the laboratory. Examination in the laboratory is normally done by a pathologist who will check if the cells in the tissue are cancerous or not. In most cancer cases, biopsy is considered to be the confirmatory test. Depending on the location and type of cancer, biopsy can be obtained in different ways. Some of them include;
Using needle. By using a thin needle, doctors can draw same tissue or fluid for examination under microscope. This method can be used to draw some fluid (spinal tap), bone marrow (bone marrow aspiration), blood or small amount of tumor from the suspected organ such as liver and breast (fine needle aspiration).
Surgery. Abnormal tissue samples are obtained while the doctor is performing the surgery. Tissues are then sent to the lab for examination during the surgery. If the surgeon removes just a portion of abnormal area it is called incisional biopsy while when the entire tumor (abnormal site) is removed it is called excisional biopsy.
Using endoscope. Endoscope is a thin, lighted tube with a camera (focusing telescope) at the end. It is used for viewing inside the body through natural openings like mouth and anus. During an examination if the doctor sees any abnormal tissue, then endoscope can also be used to take sample for that tissue. There are different kinds of endoscopy exams depending on the site of the body being examined. Some of the exams include colonoscopy (for rectum and colon), bronchoscopy (for trachea, bronchi and lungs) and esophagogastroduodenoscopy EGD (for esophagus, stomach and duodenum). In addition to medical history and physical examination, diagnosis of anal cancer normally involve the use of anoscopy and proctoscopy which are types of endoscopy, ultrasound, biopsy and other imaging tests like CT scan, MRI scan, chest X-ray, and PET scan.
Staging of anal cancer.Staging is a standard way used by cancer care team to explain how far the cancer has grown or spread. Once an imaging modality has helped to establish a probable diagnosis of anal cancer, the next issue is deciding suitable treatment option for the disease. Staging has enabled oncology team to decide on the suitable treatment option. In this process of staging doctors normally use systems in order to describe the stage of cancer. For describing anal cancer, TNM staging system (tumor, node and metastasis) is normally used.
TNM staging systemTNM system is the combination of three worlds, tumor, node and metastasis.
> Tumor. Tumor explains size (how large is the tumor?) and its location.
> Node. This explain lymph nodes involved
> Metastasis. Metastasis explains how far has disease spread?
There are five stages under this system, stage zero (0) to four (0 –IV). More discerption on this TNM system is as follows;