Pathological fracture as initial manifestation of malignancy and survival based on diagnoses: a register-based cohort study from the Swedish Fracture Register and the Swedish Cancer Register.

Background and purpose: Pathological fracture as the initial manifestation of malignancy is a clinical challenge requiring rapid treatment despite limited prognostic information. We aimed to describe definitive diagnoses and survival in patients presenting with a pathological fracture as initial manifestation of malignancy.

Methods: We performed a nationwide register-based cohort study using the Swedish Fracture Register (SFR) and Swedish Cancer Register (SCR), 2014-2023. We included patients with a pathological fracture classified as unknown in the SFR at treatment. Survival was analyzed using Kaplan-Meier and Cox regression.

Results: We included 319 patients with a pathological fracture. Median age was 75 years (17-100), 50% men. A definitive tumor diagnosis was established in 215 patients (67%), most commonly a hematogenous malignancy. Age was associated with mortality (HR 1.03, 95% confidence interval [CI] 1.01-1.04). Compared with hematogenous malignancies, mortality was higher for bone (HR 2.9, CI 1.2-7.2), breast (HR 2.5, CI 1.2-5.1), kidney (HR 3.3, CI 1.7-6.5), lung (HR 6.3, CI 3.7-10.5), unknown (HR 8.1, CI 4.2-15.5), other (HR 10.3, CI 5.6-19.0), and gastrointestinal malignancies (HR 10.3, CI 4.5-23.7), and for patients without SCR registration (HR 19.7, CI 11.7-33.2). Prostate cancer, sex, fracture site, and treatment were not associated with increased mortality.

Conclusion: Hematogenous and lung malignancies were the most common in pathological fracture as initial manifestation of malignancy. Survival was short and varied substantially by tumor type. Age and primary tumor site were prognostic factors, emphasizing the importance of comprehensive diagnostic work-up to guide acute treatment.