Prostate Specific Membrane Antigen (PSMA) PET-CT scan is the latest and most advanced technology available for the evaluation of patients with prostate cancer.
It has been available for only a few years in the most advanced health centres in the world. The technology is presently only available in a few health centres in Africa, and has not been available in East Africa until now.
Though MRI and CT scans have been available for long for study of prostate cancer by providing anatomical (structural) information, the PET-CT scan is able to provide vital additional functional or molecular information.
This significantly increases the ability or sensitivity of the scan to detect the spread of prostate cancer. This is achieved by injecting a small amount of a radioactive substance which binds to prostate cancer cells in the body.
How it works
The site of these cells can then be detected using the PET-CT scanner, which detects the radioactivity emitted from the radioactive substance using the PET scan and correlates it with the exact anatomical location provided by the CT scan. Several radioactive substances can be used for this scan.
The radioactive substance that we, as Aga Khan University Hospital, are using is Fluorine-18 PSMA, which is produced using a cyclotron and complex radiochemistry procedures. This is the latest and the most accurate and sensitive radioactive substance available for this scan. Its radioactivity decays very quickly and is over within a few hours. Thus it needs to be produced within the vicinity of the institution performing the scan.
Following advancement in our PET-CT scan technology capacity and growth in the expertise of our radiology and laboratory departments, we are now able to produce the radioactive substance required for this scan using our cyclotron and radiochemistry lab, as well as conduct the test, at the Aga Khan University Hospital, Nairobi. This will be a significant development in the management of prostate cancer in the region.
How is the test done?
The scan takes approximately two hours. It involves the injection of a small amount of the radioactive substance (radiotracer) through a vein. The radiotracer is then allowed around one hour to distribute within the body after which the patient is placed in a PET-CT scanner.
What does it check?
The PSMA PET-CT scan checks for sites of active prostate cancer cells. It is the most sensitive scan to look for spread of prostate cancer within the body, which happens mainly in the bones and lymph nodes. The scan takes approximately 20-30 minutes. No particular patient preparation is required for this examination.
Compared to the presently established methods of imaging prostate cancer such as MRI and bone scan, PSMA PET-CT scan has higher sensitivity for identification of sites of prostate cancer spread, be it in the bones or in any other organ such as lymph nodes, liver and lungs. It can be used for this purpose at the initial diagnosis of the disease, during follow-up and when disease recurrence is suspected.
In view of its higher sensitivity, PSMA PET-CT scan can identify sites of early prostate cancer spread before they are picked up by conventional imaging modalities. This allows for better treatment options at a very early stage which was not possible till now.
According to the Prostate Cancer Information, Education and Communication Booklet from the Uganda Cancer Institute, detecting and treating prostate cancer early can improve a man’s chance of full recovery.
The booklet points out that the risk of prostate cancer increases with age, especially after the age of 50. More than 80 per cent of prostate cancers are diagnosed in men who are 65 years or older.
About 85 per cent of prostate cancer tends to grow or progress slowly compared to most other cancers. Cell changes may begin 10, 20, or even 30 years before the persons develops symptoms of the cancer. By the time a person suffering from prostate cancer develops symptoms, the cancer may already be advanced.
Dr Nguku is the section head, PET-CT at Aga Khan University Hospital, Nairobi.
This story was first published in Daily Nation