Prostate cancer is the third most common cancer among Singaporean men. Every day for years 2014-2018, 15% of new cancer cases for men were prostate cancer cases; more than 50% occurred among those aged 70 years and above. Most prostate cancers detected early are curable and placed on active surveillance. Hence the survival rate is over 85%, five years after diagnosis.
However, at the advanced stage where the cancer cells have spread outside the prostate to other parts of the body, treatment options are more varied and complex.
Farrer Park Hospital (FPH) has introduced Actinium-225 Prostate-Specific Membrane Antigen (PSMA) Nuclear Therapy to treat advanced prostate cancer, especially for patients who were heavily pretreated with current existing forms of cancer therapy.
“We have found good responses with patients using Actinium-225 PSMA, who are typically patients with metastatic castrate resistant prostate cancers who have been heavily pre-treated, including with Lutetium 177 PSMA, but whose cancers are still progressing.” said Dr. Andrew Tan, Nuclear Medicine Physician. He also heads FPH’s Nuclear Medicine Suite (NMS).
“The nature of nuclear medicine theranostics is that there are many logistical and clinical hurdles to be considered and managed before FPH can introduce a treatment. We took a proactive approach to expand treatment options for advanced prostate cancer patients as many at this juncture of their treatment would be looking for further options,” he added.
The procedure is approximately one hour and is an outpatient procedure at FPH’s Nuclear Medicine Suite. The Actinium-225 PSMA is injected slowly through an intravenous line. There are typically no expected complications or side effects during the actual infusion. The patient typically will need 2 to 4 cycles, each cycle about eight weeks apart. The NMS has started the treatment with one patient so far, with another patient scheduled. Both are elderly males with metastatic prostate cancer.
Before starting the Actinium-225 PSMA therapy, Dr. Tan will have to screen the patient to understand the exact stage of his cancer, underlying condition and expectations. The screening usually involves a baseline blood investigation of marrow function, renal function, Prostate-Specific Antigen (PSA) levels, and a Positron Emission Tomography (PET) or Computed Tomography (CT) scan to assess the tumour PSMA ligand binding activity.
He will also take a detailed history of all previous hormonal, chemotherapy, radioligand, radiotherapy, and targeted therapy.
“The main side effect of radiation to salivary glands is dry mouth. It is by far the most common side effect. Another is marrow radiation leading to decreased cell counts. The effect is often temporary, though some patients with very advanced stages may need a blood transfusion,” Dr. Tan explained the side effects of using Actinium-225 PSMA.