Bone scan index rise prior to osteonecrosis of the jaw with bone-modifying agents in prostate cancer

This study aimed to evaluate the maximum bone scan index in the jaw (BSIJmax) before the development of clinical medication-related osteonecrosis of the jaw (MRONJ) in patients with prostate cancer.

We retrospectively analysed 135 patients with prostate cancer and bone metastases who received bone-modifying agents (BMAs) between 2008 and 2025. Bone scintigraphy data were collected at baseline and during the BMA treatment. BSIJmax was calculated using computer-assisted diagnostic software (BONENAVI). Primary endpoints were BSIJmax in the maxilla and mandible before the clinical diagnosis of MRONJ, compared with baseline values. Secondary endpoints included area under the receiver operating characteristic curves (AUCs) for diagnosing MRONJ using BSIJmax in the maxilla and mandible.

Among 135 patients, 27 developed MRONJ during a median follow-up of 74 months (interquartile range, 41-124 months). Mandibular BSIJmax values before the clinical diagnosis of MRONJ were significantly higher than baseline values (0.090 vs. 0.027, p < 0.001), whereas maxillary values showed no significant change. The AUC for mandibular BSIJmax in diagnosing MRONJ was 0.803. A mandibular BSIJmax cut-off of 0.033 yielded a sensitivity and specificity of 85% and 71%, respectively, for the diagnosis of MRONJ.

The mandibular BSIJmax increased before the clinical diagnosis of MRONJ. The incorporation of BSIJmax into bone scintigraphy may enable early detection of MRONJ and timely intervention in patients with prostate cancer receiving BMA therapy.