Risks and benefits of combining denosumab and surgery in giant cell tumor of bone-a case series.
BACKGROUND
The RANK ligand inhibitor denosumab is being investigated for treatment of giant cell tumor of bone, but the available data in the literature remains sparse and controversial. This study analyzes the results of combining denosumab with surgical treatment and highlights possible changes for the oncologic surgeon in daily practice.


METHODS
A total of 91 patients were treated surgically for giant cell tumor of bone between 2010 and 2014 in an institution, whereas 25 patients of the total additionally received denosumab and were part of this study. The average age of the patients was 35 years. Eleven patients received denosumab pre- and postoperatively, whereas with 14 patients, the denosumab treatment was applied either before (7 patients) or after (7 patients) the surgery. The average preoperative therapy duration was 3.9 months and the postoperative therapy 6 months by default.


RESULTS
Sixteen patients presented a large tumor extension necessitating a resection of the involved bone or joint. In 10 of these patients, the indication for a resection procedure was abandoned due to the preoperative denosumab treatment and a curettage was performed. In the remaining six cases, the surgical indication was not changed despite the denosumab treatment, and two of them needed a joint replacement after the tumor resection. Also with patients treated with curettage, denosumab seems to facilitate the procedure as a new peripheral bone rim around the tumor was built, though a histologic analysis reveals viable tumor cells persisting in the denosumab-induced bone formation. After an average follow-up of 23 months, one histologically proven local recurrence occurred, necessitating a second curettage. A second patient showed a lesion in the postoperative imaging highly suspicious for local relapse which remained stable under further denosumab treatment. No adverse effect of the denosumab medication was observed in this study.


CONCLUSIONS
Denosumab can be a help to the oncologic surgeon by reconstituting a peripheral rim and switching the stage from aggressive to active or latent disease. But as tumor cells remain in the new-formed bone, the surgical technique of curettage has to be changed from gentle to more aggressive to avoid higher local recurrence rates.
Department of Orthopedic Surgery, University Hospital Balgrist, Forchstrasse 340, 8008, Zürich, Switzerland. daniel.mueller@balgrist.ch.
Daniel A
DA
Müller
Department of Orthopedic Oncology, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Firenze, Italy.
Giovanni
G
Beltrami
Department of Orthopedic Oncology, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Firenze, Italy.
Guido
G
Scoccianti
Department of Traumatology and Orthopedic Surgery, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Firenze, Italy.
Domenico A
DA
Campanacci
Division of Anatomic Pathology, Department of Surgery and Translational Medicine, University of Florence, Largo Brambilla 3, 50134, Firenze, Italy.
Alessandro
A
Franchi
Department of Orthopedic Oncology, Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50134, Firenze, Italy.
Rodolfo
R
Capanna
D000293:Adolescent; D000328:Adult; D000368:Aged; D050071:Bone Density Conservation Agents / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use; D001859:Bone Neoplasms / Q000188:drug therapy / Q000473:pathology / Q000601:surgery / Q000628:therapy*; D017024:Chemotherapy, Adjuvant; D003475:Curettage / Q000379:methods; D000069448:Denosumab / Q000008:administration & dosage / Q000009:adverse effects / Q000627:therapeutic use*; D005260:Female; D005500:Follow-Up Studies; D018212:Giant Cell Tumor of Bone / Q000188:drug therapy / Q000473:pathology / Q000601:surgery / Q000628:therapy*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology*; D053245:RANK Ligand / Q000037:antagonists & inhibitors; D012189:Retrospective Studies; D018570:Risk Assessment; D016896:Treatment Outcome; D055815:Young Adult
D050071:Bone Density Conservation Agents; D053245:RANK Ligand; C505688:TNFSF11 protein, human; D000069448:Denosumab
Adjuvant treatment; Benign tumor; Bone; Denosumab; Giant cell tumor; Surgery