Thyroid cancer patients who undergo radionuclide therapy are cautioned not to go near children younger than 12 years for at least one week after treatment.
CANCER treatment methods have progressed rapidly over the past decade.
One such method that is gaining traction is nuclear medicine therapy, which uses radioactive medicines called radiopharmaceuticals to target cancer cells, with the aim to shrink and destroy them.
Dr Khor Phay Phay, a nuclear medicine physician at Sunway Medical Centre, Sunway City says that nuclear medicine has grown tremendously over the years, with multiple forms of treatment now available for cancer patients.
“With the vast expansion of cancer treatment, nuclear medicine now includes a number of other therapies and procedures to target different cancers and tumours, such as prostate cancer, liver tumours and neuroendocrine tumours.
“Over the years, nuclear medicine has been integrated in most cancer treatments and diagnosis, as newer radiopharmaceuticals are being developed with the advancement of cancer therapy.
“It is exciting to see how fast it has expanded and to see it translate from research in the laboratory to clinical practice.”
Dr Khor says that nuclear medicine therapy, also known as radionuclide therapy, used to mainly revolve around the use of radioactive iodine (RAI) to treat well-differentiated thyroid cancer, post surgery.
Now, there are other types of treatments such as selective internal radiation therapy (SIRT) for liver tumours and liver metastasis, Lutetium-177 PSMA therapy for metastatic castration-resistant prostate cancer, Lutetium peptide receptor radionuclide therapy (PRRT) for neuroendocrine tumours, Actinium PSMA therapy for metastatic castration-resistant prostate cancer and MIBG therapy for neuroblastoma and pheochromocytoma/paraganglioma.
“For certain cancers, radionuclide therapy offers hope when other conventional treatments have failed.”
Dr Khor shares that nuclear medicine physicians like herself often work closely with other healthcare professionals – like oncologists and surgeons – to come up with the best treatment plans for patients, as cancer does not present itself similarly in different patients.
Before a patient undergoes radionuclide therapy, diagnostics scans have to be conducted to determine the status of the cancer. Theranostics is a concept that is derived from a combination of therapeutics and diagnostics.
“When a cancer is diagnosed, patients will be referred for a PET-CT scan in nuclear medicine for staging purposes. This is to check if the cancer is localised or has spread to other organs (distant metastasis) – giving us a clear picture of the disease status.
“We then inject a radioactive tracer into the patient via an intravenous line, followed by a full body scan. The radiopharmaceuticals will go into the cancer cells and this will be captured on the scan images.”
Apart from radiation, there are usually no side effects from the treatment, says Dr Khor.
Dr Khor says there are different types of PET-CT scans as well, such as the F18-FDG PET-CT scan, which is done for most cancers. The Gallium-68 DOTATATE PET-CT scan is used mainly for neuroendocrine tumours and Gallium-68 PSMA PET-CT for prostate cancer.
“For PET-CT scans, they generally take a couple of hours. When the patient arrives, vital signs are first taken. Then an intravenous line has to be put in for radiopharmaceutical injection.
“Once the radiopharmaceutical is injected, the patient has to rest for 45 to 60 minutes before going to the scanners. The scan takes approximately 10 to 20 minutes. After that, the patient will have to be in the waiting area for the scans to be reviewed.”
Apart from radiation, there are usually no side effects, she adds.
“It depends on the radiopharmaceutical's half-life. For F18-FDG PET-CT, the half-life is about two hours – meaning that the radiation will reduce every two hours. The radiation will be further reduced as it is excreted in the urine.”
In radionuclide therapy, the main challenge when receiving treatment is the precautionary measures that patients will have to take after treatment.
“For example, in radioactive iodine treatment, we make sure that the patients are well aware of the radiation precautions that need to be taken.
“A patient should not be near children less than 12 years old for at least one week. Make sure to keep a distance of at least 1m,” says Dr Khor.
