Sacral Insufficiency Fracture Following Pelvic Radiotherapy in Gynaecological Malignancies: Development of a Predictive Model.

AIMS: To investigate the time-to-event and the evolution of sacral insufficiency fractures in gynaecological patients receiving pelvic external beam radiotherapy (EBRT) in relation to dosimetric and imaging parameters across a spectrum of radiotherapy delivery techniques, and to develop a predictive model with a clinical nomogram to identify those at risk of sacral insufficiency fracture. MATERIALS AND METHODS: Patients who received radical or adjuvant pelvic EBRT for gynaecological malignancy between 2014 and 2019 were identified. The data collected were: demographics and clinical details; radiotherapy planning data: dose, fractionation, technique (fixed-field intensity-modulated radiotherapy, adaptive arc, and non-adaptive arc), 60 Gy simultaneous integrated boost. Each plan was examined to determine the sacral dose in 5%/Gy3 increments. Follow-up magnetic resonance scans were reviewed for insufficiency fractures, defined as linear low T1-weighted signal intensity with a high short-T1 inversion recovery (STIR) signal. The site of insufficiency fracture was recreated on the planning computed tomography, the dose to insufficiency fracture contours was recorded and insufficiency fractures were determined as healed with resolution of high STIR signal. Univariable analysis was conducted of the clinical variables. The area under the receiver operator characteristic curve and odds ratio of the risk prediction model with 95% confidence interval are reported with a nomogram for use in clinical practice. RESULTS: 115 patients were identified; the median imaging follow-up was 12 months (2-47). 37.4% developed sacral insufficiency fractures; 93.0% were detected within 12 months of EBRT. At the final radiological follow-up, 83.7% of insufficiency fractures remained active. The radiotherapy delivery technique was not associated with insufficiency fracture after adjusting for patient age (P = 0.115). The location of the 60 Gy simultaneous integrated boost planning target volume did not impact upon the site of insufficiency fracture or the dose received by the insufficiency fracture sites. Age and V40Gy3 are predictors for insufficiency fracture and form the clinical risk model (receiver operator characteristic 0.72). CONCLUSIONS: Age and V40Gy3 predict sacral insufficiency fractures; future work should focus on optimising radiotherapy planning with adoption of a bone-sparing planning approach for those patients at high risk of insufficiency fracture.

Direct skin involvement of cervical lymph node metastasis from mucosal squamous cell carcinoma of the head and neck.

INTRODUCTION: Direct skin involvement of nodal metastasis from mucosal head and neck squamous cell carcinoma has traditionally been considered a poor prognostic indicator. METHODS: This retrospective review identified eight patients (five with mucosal upper aerodigestive and three with occult primary squamous cell carcinoma) who presented between 2000 and 2007 with direct skin involvement of nodal metastasis. RESULTS: Five patients were treated with extended radical and three with extended modified radical neck dissection. Closure was achieved directly (four cases), with local (two) or pedicled (two) flaps. Surgery was always followed by radiotherapy (pan-mucosal or to the primary site). The five-year recurrence-free and disease-specific survival rates were 100 per cent. CONCLUSION: It is exceptionally rare to encounter direct skin involvement of metastatic lymph nodes from mucosal head and neck squamous cell carcinoma without evidence of involvement of other anatomical structures. Surgical intervention is possible and combined modality treatment with curative intent is essential, as most patients can have a favourable outcome.