New technology to boost prostate cancer treatment

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.

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.

CANCER SPREAD

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.

What are the advantages of using this test as opposed to what we have been doing? 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.

What difference does it make in the management of prostate cancer? 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 of the disease at a very early stage which was not possible till now. This is bound to have a major impact on treatment outcome for those with prostate cancer.

Dr Nguku is the section head, PET-CT, and Dr Makhdomi is the section head, Nuclear Medicine at Aga Khan University Hospital, Nairobi.