icotec’s BlackArmor® Carbon/PEEK material offers new opportunities in radiation therapy of spinal tumours
Up to 40 per cent of all cancer patients will develop a secondary tumour in the spine (Singh et al., 2006). In the decision for surgical treatment, spinal decompression and subsequent stabilisation of the spinal column with implants is paramount. The removal of the tumour will be considered concurrently. For pain and local control of the tumour, supplemental radiation therapy utilising photons or protons is often applied postoperatively.
The presence of metal spinal implants will cause significant artefacts in the planning images utilised for radiation therapy. The artefacts make it much more difficult to delineate anatomic structures during dose planning and require more time to correctly calculate the proper dose distributions. In contrast to metal implants, icotec’s BlackArmor® biomaterial is a non-metallic, high strength composite material, made from continuous carbon fibres embedded in a PEEK-polymer matrix. Due to its radiolucent nature, the BlackArmor® biomaterial causes only negligible imaging artefacts, enabling a precise demarcation of the tumour and planning of the doses in radiation therapy. The time-consuming manual corrections known from metallic implants are obsolete.
During radiation therapy, metal implants will shield remaining tumour cells from the radiation and cause scattered radiation into the surrounding healthy tissue and organs. In some cases, patients with metal implants must be excluded from curative proton therapy. In contrast, BlackArmor® Carbon/PEEK implants allow the radiation beam to pass unimpeded through the material into the initially planned tumour tissue, without shielding or beam scattering. This minimises the risk of a radiation dose that is either too high or too low and thereby protects sensitive tissue. During follow-up control for recurrent disease in peri-implant tissues, which is usually difficult in areas adjacent to metal implants, the non-metallic BlackArmor® biomaterial also facilitates significantly better diagnostic images (CT and MRI).
New data (Schneider 2016) from the Center for Proton Therapy at Paul Scherrer Institute show for the first time, patients with metal implants treated with protons have a significantly (p< 0.05) lower overall survival (49 per cent) than those without any metal implant (66 per cent). It is currently unclear if this difference originates from metal implants compromising proton radiation or if the more aggressive disease is a co-factor. An in vitro study by Kashua (2016) compared spinal constructs made from titanium vs. BlackArmor® Carbon/PEEK biomaterial in a radiation-oncology setup. The group found significantly reduced artefacts for BlackArmor® material which resulted in a more accurate and homogenous dose planning.
Clinical experiences with BlackArmor® Carbon/PEEK pedicle screws in spinal tumour surgery have been published by Eicker et al, 2014 and 2016 and Süss et al, 2014. Both groups confirmed simplified and better dose-planning and radiation therapy with BlackArmor® Carbon/PEEK implants.
icotec’s BlackArmor® biomaterial, utilised in CE-marked products since 2000 and with FDA clearance in 2005, is the result of a unique combination of continuous, high strength carbon fibres and icotec’s composite flow moulding (CFM) process. As such, complex shaped implants for load-bearing applications like pedicle screws or vertebral body replacements can be made from BlackArmor® biomaterial.
References available upon request.