(P 347) CAN UPFRONT RADIOTHERAPY PRECLUDE THE NEED FOR OPERATIVE STABILIZATION IN IMPENDING EXTREMITY FRACTURES FROM LUNG CANCER METASTASES?

Objective: Deciding to operate on cancer patients with bony metastases requires balancing symptoms, prognosis, care goals, treatment stage, and fracture risk. Not all bony metastases have an equal risk for pathologic fractures. The Mirels scoring system helps determine the need for prophylactic fixation, but clinical judgment plays a major role in treatment decisions. Additionally, treatment choices are also based on histology, but there is limited literature addressing this approach. This study aims to assess how up-front radiotherapy affects fracture risk and outcomes in lung cancer patients with osseous metastases to the appendicular skeleton.

Methods: A retrospective review at Moffitt Cancer Center (2006-2023) evaluated radiotherapy for metastatic lung cancer to the appendicular skeleton. Inclusion criteria were metastatic appendicular bone lesions confirmed by biopsy/imaging, appropriate imaging, and a documented clinical assessment. Exclusion criteria were pathologic fractures, inadequate imaging, prior prophylactic fixation, non-lung cancer metastases, and axial skeleton lesions.
Out of 359 patients reviewed, 83 with 89 lesions were included. Data included age, gender, weight/BMI, Mirels Criteria (pre- and post-radiation scores), surgery details, fracture occurrence, radiotherapy dates/dosage, and lung cancer pathology. Patients were divided into surgery and non-surgery groups, and statistical analysis assessed risk factors for progression, fracture, or surgery need.
Primary outcome was whether a patient was successfully treated with upfront radiation therapy, defined as no prophylactic stabilization or fracture needing fixation. Descriptive and Chi Square analyses were used, with statistical significance set at P < 0.05.

Results: Of the 83 patients with 89 osseous lesions, 46 patients were female (55.4%) with an average age of 61.9  13.1 years. The most common pathology was Non-small Cell Lung Cancer (79.8%) followed by Adenocarcinoma (12.0%), Small Cell Lung Cancer (5.6%), and mixed NSCLC/SCLC (3.6%).
78 (88.8%) lesions were successfully treated non-operatively with radiotherapy. Of these, 78.2% (61/78) had Mirels scores of 8 or greater. Of the 11 lesions that required stabilization following radiotherapy, 7 were due to fracture and 4 were due to persistent pain. Non-operative and operative groups had comparable histological subtypes, age, sex, and BMI. Larger lesion size and lytic appearance were significantly correlated with increased risk of surgery (p=0.01 and p=0.02 respectively). Mean Mirels score was significantly higher for the operative group (p=0.001). There was no significant correlation between radiotherapy dose and surgical risk.

Conclusion: A higher Mirels score correlates with increased risk of requiring surgical intervention, but radiotherapy is largely sufficient in preventing pathologic fractures in lung cancer patients with high-risk appendicular skeleton osseous metastases.