Measurable progression of giant cell tumour of bone associated with pregnancy - A tertiary sarcoma centre analysis.

Introduction: Giant cell tumour of bone (GCTB) is a benign but locally aggressive bone tumour with a higher predilection for females of reproductive age. GCTB management poses a unique set of challenges during pregnancy due to risks associated with imaging and treatment options. Pregnancy has been implicated in GCTB progression and tumour recurrence, however an exact mechanism has not been established. This study aims to confirm the relationship between the diagnosis and progression of GCTB during pregnancy. Methods: A 17-year retrospective analysis of our tertiary sarcoma referral centre database was performed to identify the relevant patients. Pregnancy-associated tumours were defined by those already present or diagnosed during pregnancy, and up to 12 months postpartum. Lesion volume was determined by mathematical ellipsoidal modelling technique to simplify the estimation, with cross-sectional measurements obtained from the three standard orthogonal planes on initial and surveillance imaging. Due to logistical challenges, follow-up imaging was performed at either our tertiary sarcoma centre or under guidance at regional imaging centres convenient to the patient. Results: The diagnosis of GCTB was made in 113 female patients during this 17-year period, of which 20 were associated with pregnancy with a mean age of 28.8 years (range 19-40 years). 12 patients had their primary or recurrent GCTB diagnosed, or known tumour progress during pregnancy, whilst the remaining 8 were diagnosed shortly thereafter to within 12 months postpartum. The most common tumour sites were located around the knee (30 %) and distal radius (25 %). A statistically significant pattern of growth was observed through the surveillance period (p 0.018), within a relatively short mean follow-up period of only 89.8 days (SD 54.5; 13-192 days). Conclusion: This study demonstrates the significant association that pregnancy has with the growth and progression of both primary and recurrent GCTB. Pregnant patients should be subject to close surveillance well into the postpartum period due to possible accelerated disease progression and potential for disease recurrence.