Endocrine Connections (Jun 2023)
Radiotherapy-related insufficiency fractures and bone mineral density: what is the connection?
Abstract
Background: Radiotherapy-related insufficiency fractures (RRIFs) represent a common, burdensome consequence of pelvic radiotherapy. Their underlying mechanisms remain unclear, and data on the effect of osteoporosis are contradictor y, with limited studies assessing bone mineral density (BMD) by dual-energy x-ray absor ptiometry (DXA). Methods: BMD by DXA (Hologic) scan and fracture risk following pelvic R RIF were retrospectively assessed in 39 patients (median age 68 years) a t a tertiary cancer centre. Patient characteristics and treatment history are presented narratively; correlations were explored using univariate regression analyses. Results: Additional cancer treatments included chemotherapy (n = 31), surgery (n = 20) and brachytherapy (n = 19). Median interval between initiation of radiotherapy and RR IF was 11 (7.5–20.8) and that between RRIF and DXA 3 was (1–6) mon ths. Three patients had normal BMD, 16 had osteopenia and 16 osteoporosis, followin g World Health Organization classification. Four patients were –2). Median 10-year risk for hip and major osteoporotic fract ure was 3.1% (1.5–5.7) and 11.5% (7.1–13.8), respectively. Only 33.3% of patients had high fracture risk (hip fracture >4% and/or major osteoporotic >20%), and 31% fell abov e the intervention threshold per National Osteoporosis Guidelines Group (NOGG) gui dance (2017). Higher BMD was predicted by lower pelvic radiotherapy dose (only in L3 and L4), concomitant chemotherapy and higher body mass index. Conclusion: At the time of RRIF, most patients did not have osteoporosis, some had normal BMD and overall had low fracture risk. Whilst low BMD is a prob able risk factor, it is unlikely to be the main mechanism underlying RRIFs, and further studies are required to understand the predictive value of BMD.
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