Anal Cancer Investigations – Tests for Diagnosis and Staging


anal cancer investigations

Anal Cancer Investigations-Tests for Diagnosis and Staging

If an individual is suspected to have anal cancer due to signs and symptoms, some investigations are required to confirm the diagnosis of the disease. Further, these can help in determining the stage of disease, which in turn help in choosing an appropriate treatment option.



Anoscopy is a diagnostic technique which uses an anoscope – a cylindrical device equipped with a light source, and some special instruments for biopsy or surgery. This enables the doctors to closely examine the surface of the anal canal to determine the presence of cancerous or precancerous lesions. The physician can also collect biopsy sample{s} if an abnormal area is observed during the procedure.



Biopsy sample(s) from the anal region or the affected lymph nodes are generally collected in case an abnormal area(s) is observed during the anoscopy procedure or during the physical examination indicating enlarged lymph nodes. It can provide information such as the type of cancer, the severity of cancerous changes involved (grade of cancer), and the presence of specific defective genes or proteins.

Imaging Tests

These tests are generally employed after the establishment of the pathological diagnosis. They help to detect the spread of disease to distant body parts and assess the stage of the disease so that an appropriate treatment option can be selected. Alternatively, these tests are employed after treatment to evaluate the treatment efficacy and to detect disease response, progression, or recurrence.

Transrectal Ultrasound

Transrectal Ultrasound - Resectoscope

In normal ultrasound, a transducer is used which directs very high-frequency sound waves towards the tissue to be examined. In transrectal ultrasound, the transducer is placed directly into the rectum. The sound waves are reflected off the internal structures depending on their ability to reflect these waves. The reflected sound waves are collected by a special detector (fixed near the transducer) to produce a real-time image of the internal tissues on a computer screen. This helps the doctor to examine the nearby tissue for any abnormality. This test can detect solid tumor masses (cancerous) within the anus or nearby area(s), which can be further evaluated with the help of other diagnostic tools.

Computed tomography (CT) scan

CT Scan

In this technique, detailed cross-sectional images of body organs are generated using x-rays, with or without a contrast medium. It can help diagnose the spread of disease to nearby/distant lymph nodes and other organs, and may also be used to guide a biopsy needle into the affected area.

Positron emission tomography (PET) scan

PET Scan

This technique uses a radioactive substance (e.g.fluorodeoxyglucose [FDG]) that is given intravenously prior to the procedure. Cancer cells absorb larger amounts of the radioactive substance than normal cells. The areas of higher radioactivity indicate cancerous tissue on the PET scan. Thus, this technique can diagnose the spread of disease to distant body parts. It is usually combined with CT scan (PET/CT).

Magnetic resonance imaging (MRI) scan

MRI Scan

This technique provides detailed images of tissues inside the body using radio waves, strong magnetic field, and gadolinium contrast. It can accurately diagnose the extent of invasion and spread of disease to nearby/distant body parts.

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