Objective: To identify an objective and reproducible strategy for preoperative staging bone scintigraphy (BS) in patients diagnosed with renal cell carcinoma (RCC), because in the absence of objective criteria, the decision to perform preoperative BS remains a subjective practice.
Patients and methods: The study included a total of 2008 patients with RCC treated with surgery and prospectively included into an institutional database. The study outcome was the presence of 1 or more bone lesions suspicious for metastases at staging BS. A multivariable logistic regression model predicting a positive BS was fitted. The predictors consisted of the preoperative clinical tumor (cT) and clinical nodal (cN) stages, the presence of systemic symptoms, and the platelet-to-hemoglobin (PLT/Hb) ratio.
Results: The rate of positive BS was 4% (n = 81). At the multivariable logistic regression analysis, cT2, cN1, the presence of systemic symptoms, and the PLT/Hb ratio were all associated with am increased risk of positive BS (P <.05). Following the 2000-sample bootstrap validation, the concordance index was 0.77 (proposed model) vs 0.63 (decision making based on symptoms only). At the decision curve analysis, the proposed strategy was associated with a higher net benefit. If BS is performed when the risk of positive result is >5%, a negative BS is spared in 80% and a positive BS is missed in 2% of the population only.
Conclusion: Using preoperative variables, it is possible to accurately estimate the risk of positive BS at RCC staging using preoperative characteristics. Compared with the strategy supported by available guidelines, the proposed model was more objective, statistically more accurate, and clinically associated with higher net benefit.
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