Extracorporeal irradiation of tumorous calvaria: a case series

Abstract

OBJECT When intracranial tumors invade the overlying skull, gross resection typically includes removal of the involved bone. Methods used to repair the resulting structural defect in the cranium include artificial prostheses, allogeneic bone grafts, and autoclaving the autologous graft. The authors have previously reported a case involving high-dose extracorporeal ionizing radiation to treat the tumorous calvaria intraoperatively, followed by reimplantation of the treated bone flap. In this paper the authors report the long-term follow-up of that case, as well as results of using extracorporeal irradiation of tumorous calvaria (EITC) for an additional 20 patients treated similarly. METHODS The decision to undergo EITC was typically anticipated preoperatively, but determined intraoperatively, if upon inspection the bone flap was invaded by tumor. The bone flap was then delivered to the radiation oncology department, where a total dose of 120 Gy was delivered, using a clinical linear accelerator, over a period of approximately 15 minutes. After the intracranial tumor resection was completed, the irradiated craniotomy bone flap was reimplanted and the wound was closed in a standard fashion. A retrospective review of patients who had undergone EITC was performed for evidence of calvarial tumor recurrence or other complications. RESULTS Since the originally reported case, 20 additional patients have received EITC during craniotomy for invasive tumors. Eighteen (86%) of 21 patients were diagnosed with meningioma: 12 (67%) with WHO Grade I, 5 (28%) with WHO Grade II, and 1 with WHO Grade III (6%). The remaining 3 patients presented with dural-based B-cell lymphoma with extensive adjacent bone invasion (n = 2) and metastatic adenocarcinoma of the lung (n = 1). Follow-up of the 21 patients ranged from 1 to 132 months, with a mean of 41 months and a median of 23 months. No patients have experienced tumor recurrence, infection associated with the treated calvaria, or evidence of bone flap resorption. CONCLUSIONS Calvaria reconstructions represent an important component in structural and cosmetic outcome following craniectomy for tumorous bone. The authors' long-term experience with EITC has been excellent with no local tumor recurrence or complications. Therefore, EITC represents an excellent and efficient option for cranial reconstruction in such patients.

Intra-operative extracorporeal irradiation of tumour-invaded craniotomy bone flap in meningioma: a case series

“…In 14 cases the tumour infiltration was limited to the bone flap (convexity and parasagittal), while in 4 cases it extended beyond the bone flap (lateral sphenoid wing/spheno-orbital). CNS WHO grades higher than grade 1 may be over-represented (40%) but this is in keeping with other series of bone invasive meningioma requiring calvarial reconstruction [ 17 , 28 ], and likely reflects the more aggressive behaviour of higher grade meningiomas.…”

“…Bone resorption was one of the anticipated complications and was reported to some degree in all of the four first reported cases of EITC when 30,000 Gy was delivered [ 16 ]. However, bone resorption has not occurred in the present series nor any of the more recently published cases of EITC for meningioma when up to 120 Gy was used [ 13 , 18 , 28 ]. This is in contrast to series of autoclaved bone which report resorption rates of up to 19% [ 30 ], and reduced torsional strength in an animal model [ 14 ].…”

“…Achieving good reconstructive results is made more challenging if there is tumour invasion of the calvaria, in which case reconstruction may require a partial or entire replacement of the craniotomy flap with a variety of materials [ 5 , 31 ], autologous or allogeneic bone grafting [ 29 ], autoclaving [ 30 ], or irradiating the autologous bone flap. To date only 23 cases of extracorporeal irradiation of tumour-infiltrated calvarial (EITC) flap have been published [ 13 , 16 , 18 , 28 ].…”

“…These include pre-manufactured individualized implants [ 5 ], and generic materials, including PMMA and titanium mesh, that can be adapted by the surgeon intraoperatively. In cases where the bone is infiltrated but its architecture and mechanical strength largely preserved, reimplantation of the bone flap after its treatment in the autoclave [ 30 ], or with high dose radiotherapy, termed extracorporeal irradiation of tumorous calvaria (EITC), could be an alternative [ 28 ]. However, little is known about EITC’s functional efficacy and safety as to date only 23 cases have been reported in total [ 13 , 16 , 18 , 28 ].…”

“…In cases where the bone is infiltrated but its architecture and mechanical strength largely preserved, reimplantation of the bone flap after its treatment in the autoclave [ 30 ], or with high dose radiotherapy, termed extracorporeal irradiation of tumorous calvaria (EITC), could be an alternative [ 28 ]. However, little is known about EITC’s functional efficacy and safety as to date only 23 cases have been reported in total [ 13 , 16 , 18 , 28 ]. Furthermore, despite the utility of these techniques, each have their own complication profiles due to the technique itself or the material used.…”