PARIS – Radionuclide therapy can alleviate painful bone metastases in 63%-75% of men with prostate cancer, reducing the need for narcotic analgesics, according to the results of an 841-patient, retrospective, single-center study.
Investigators concluded that based on their experience at Hôpital René Huguenin in Saint-Cloud, France, treatment with strontium-89 chloride can be suggested as a "valuable supplement" to other treatments currently used. The hospital is part of the Curie Institute Hospital Group.
Dr. Alain Pecking
"Bone metastases are present in more than 90% of patients who die from prostate carcinomas," Dr. Alain Pecking told attendees at the annual meeting of the International Society of Geriatric Oncology. In addition to pain, metastases in the bone can lead to fractures and neurologic symptoms, and can compress the spinal cord, he said, all of which can have a significant impact on the patient’s ability to function normally and can increase their reliance on others to perform daily tasks.
For the past 18 years, Dr. Pecking of the department of nuclear medicine at Hôpital René Huguenin has been using radionuclide therapy with strontium-89 chloride to treat patients with painful bone metastases.
A bone-targeting, beta-emitting radionuclide, strontium-89 chloride (Metastron) is deposited in metabolically active regions of bone. It has a long half-life (more than 50 days); after a single infused dose of 148 MBq – the equivalent of about 9 Gy of radiation – about 80% is retained in the tumor at 100 days.
The rationale for using strontium-89 is that many patients suffer from painful bone metastases despite using current therapies, which includes narcotic analgesics, hormonal treatments, chemotherapy, bisphosphonates, and external beam radiotherapy.
To look at the effects of radionuclide therapy on pain caused by multiple bone metastases secondary to prostate cancer, Dr. Pecking and colleagues retrospectively looked at the medical records of men who were treated with strontium-89 at their institution. All participants were using narcotic analgesics, and the aim was to see whether strontium-89 therapy could reduce the need for their use.
The researchers studied the records of 841 patients with a median age of 73 years. Dr. Pecking reported that if there was a partial response or if the patient relapsed after a complete response to strontium-89, a second infusion was given to 268 men (median age, 71 years) and a third to 86 men (median age, 70 years). Patients who received one or two infusions had 12-16 metastatic sites, of which about 4 were painful, whereas those who needed three doses had about 7 painful sites.
A complete or global response was defined as the disappearance of more than 80% of all painful metastatic bone sites and a significant decrease in the use of narcotic analgesics. A partial response was defined as a reduction in pain of more than 40% without any significant reduction in the daily use of narcotic analgesics. A slight change, no change, or increase in the use of narcotic analgesics was regarded as treatment failure.
"From one infusion [of strontium-89] you have 63% good responses, and after two courses you have 75%," Dr. Pecking said. A "good" response equated to the number of complete plus partial responses, which for one infusion was 12.6% and 50.4%, and for two infusions was 21.4% and 53.7%. The number of complete and partial responses after three doses of strontium-89 was 15.1% and 43%, respectively.
The time to response was 11 days following one infusion, 14 days after two infusions, and just over 15 days after three infusions. The duration of the pain-easing effect was longest (158 days) after one infusion, decreasing to 138 days after two and 101 days after three infusions.
Pain was a common side effect of treatment, occurring in just fewer than quarter of patients during the first 15 days after an infusion.
Prostate-specific antigen levels also spiked after the first infusion in 681 patients (81%), but this is not a problem according to Dr. Pecking. "It is necessary to explain this phenomenon to the patient and to his medical doctor, but it is not a contraindication to the treatment."
Spine neurologic syndrome was observed in three patients within 4 months after the infusion, and external radiation therapy was necessary in one case. Colitis was seen in 4.8% of patients, and grade 2-4 platelet toxicity was seen in 5.1%, 11.9%, and 13.2% of patients after the first, second, and third infusions, respectively.
"Radionuclide therapy of painful bone metastases may improve the patient’s quality of life in more than 60% of all treated cases, and can be suggested as a valuable supplement to other modalities currently used," Dr. Pecking said.