Anal cancer is an uncommon type of cancer that begins in the cells of the anal canal, the short tube at the end of the rectum. Early identification of anal cancer allows for more effective treatment approaches. This article provides an overview of how anal cancer is typically found, from recognizing initial signs to specific diagnostic tests and screening methods for individuals at higher risk.
Recognizing Potential Signs
Several symptoms and physical changes can signal a concern in the anal area. One of the most frequently reported signs is bleeding from the anus or rectum, which might be noticed during bowel movements. Individuals might also experience pain, discomfort, or persistent itching in or around the anus. These sensations can sometimes be accompanied by a lump or mass in the anal canal or around the anal opening. Changes in bowel habits, such as increased frequency, altered stool consistency, or a feeling of constantly needing to defecate, can also occur.
In some instances, there might be a discharge of mucus or pus from the anus. Swollen lymph nodes, particularly in the groin area, may indicate that cancer cells have potentially spread. These symptoms are not unique to anal cancer and can be caused by other less serious conditions like hemorrhoids or anal fissures, but they warrant medical evaluation.
Initial Medical Assessment
When an individual seeks medical attention for concerning anal symptoms, a doctor typically begins with a thorough medical history. This involves discussing the specific symptoms, their duration, and any relevant risk factors for anal cancer. Following the history, a physical examination is performed. This usually includes a visual inspection of the anal area to look for visible abnormalities, such as unusual skin changes, redness, or lumps.
A digital rectal examination (DRE) is also a standard part of this initial assessment. During a DRE, the doctor inserts a gloved, lubricated finger into the anus and rectum to feel for lumps, growths, or other changes in the anal canal. The doctor may also check the groin area for enlarged lymph nodes. For women, a pelvic exam may also be included. If these initial steps raise suspicion, the doctor may then refer the individual for further specialized tests.
Definitive Diagnostic Tests
Once initial concerns are raised, specific medical procedures are used to confirm a diagnosis of anal cancer and determine its extent. A biopsy is the primary method for diagnosis, involving the removal of a tissue sample from any suspicious area for microscopic examination by a pathologist. This tissue collection can often occur during an anoscopy, where a short, hollow tube with a light is inserted into the anus to visualize the lining and take samples.
After a cancer diagnosis is confirmed, imaging tests are used to determine the cancer’s stage, which indicates how far it has spread. Computed tomography (CT) scans use X-rays to create detailed cross-sectional images, helping to identify if the cancer has spread to lymph nodes or distant organs like the liver or lungs. Magnetic resonance imaging (MRI) uses magnetic fields and radio waves to produce detailed images, useful for assessing lymph node involvement and potential spread to areas like the liver or spinal cord. Positron emission tomography (PET) scans involve injecting a radioactive substance to highlight areas of abnormal metabolic activity, which can indicate cancer spread and assist in staging. Often, a PET scan is combined with a CT scan (PET-CT) for comprehensive imaging.
Screening for High-Risk Individuals
For individuals without symptoms but with elevated risk factors for anal cancer, proactive screening methods are sometimes recommended. Those at higher risk include people with HIV, a history of certain human papillomavirus (HPV) infections, and organ transplant recipients. The goal of screening is to detect precancerous changes or early-stage cancer before symptoms appear, potentially making treatment more effective.
One common screening tool is the anal Pap test, similar to the cervical Pap test. During this procedure, a moistened swab is inserted a few inches into the anal canal and rotated to collect cells from the lining. These cells are then sent to a laboratory to be examined under a microscope for abnormalities. Another method is high-resolution anoscopy (HRA), which uses a magnifying device, similar to a colposcope, to examine the anal canal in detail. If abnormal areas are identified during HRA, a biopsy can be taken for analysis. While general population screening for anal cancer is not widely recommended, these specialized tests can be valuable for at-risk groups.