Antonio Manca, Institute for Cancer Research and Treatment, Turin, Italy, told Spinal News that while today interventional radiologists are called in to perform osteoplasty and vertebroplasty for palliative care, the time will come one day to go beyond palliation with “enhanced” cements to offer a powerful, local, complete treatment.
What is the context of bone cement use in the treatment of spine and bone metastases?
Acrylic bone cements have been used since the nineties for the treatment of painful lytic bone metastases both in spinal and extraspinal lesions. By injecting polymethylmethacrylate (PMMA) in these lesions, bone consolidation and pain relief can be safely obtained. To date, at our interventional radiology unit (directed by Giovanni Carlo Anselmetti), 168 extraspinal lesions have been treated with percutaneous osteoplasty in 125 patients as presented by me at the European Conference of Interventional Oncology (ECIO) 2010. We mainly treated pelvic and femoral lesions, but also any other bone, safely reachable by a needle, ranging from hands and feet to scapula.This wide case series comes from our experience of thousands of vertebrae treated with percutaneous vertebroplasty (from the first cervical level to sacrum and coccyx).
What are the limitations of PMMA bone cements?
Polymethylmethacrylate, used for decades in orthopaedics and interventional radiology, provides pain relief and bone stabilisation but has a mild and unreliable antiblastic effect mainly due to heating during polymerisation and chemical toxicity of monomer. This limits stand-alone percutaneous osteoplasty/vertebroplasty to palliative care even if most of the patients have a poor life expectancy and require just palliation.
We recently published an “in vivo” study about polymerisation temperature curves of 11 different bone cements finding that none of these is able to provide an effective thermal ablation.
If we want to provide also tumoral necrosis, going beyond palliation, we need to combine ablation techniques (radiofrequency, microwaves, cryoablation, focused high intensity ultrasound) with osteoplasty or vertebroplasty.
What exactly are enhanced cements and where do you see the future?
Enhanced cements are those promising bone cements with antiblastic capabilities. These are drug-eluting bone cements containing chemotherapeutic agents, cements with radioisotopes for a sort of brachytherapy or cements containing magnetic particles that can be heated using external magnetic fields.
There are really few papers about these topics and some of these contain old ideas (drug-eluting bone cements were first described 20 years ago) and there are very few researchers working on oncologic applications of bone cements compared with the several working on reabsorbable osteoinductive cements.
Since commercial interests of chemotherapeutic drugs and interventional devices are not currently linked I think there is a lack of investors in this field and maybe we will wait for a long time before we see their commercial use.
It boils down to the fact that once we have been able to safely place a needle almost in any lesion, what really makes the difference is what we are injecting in.
Today we keep using PMMA (maybe a more viscous variety, but still PMMA) and an antiblastic effect is still missing. Osteoplasty and vertebroplasty need this antiblastic effect in order to become a complete treatment for bone metastases.
With enhanced cements, we can also obtain tumoral necrosis, avoiding the need to combine osteoplasty and vertebroplasty with ablation techniques. This way we can have a reduction of time, costs, and the risks associated withadding a second procedure.