The final study population comprised 123 lung metastases from 80 patients (mean age, 71 ± 10 years, with 60 men). Of the 123 lesions, 31 (39%) progressed to polymetastatic disease. A multivariate analysis identified three clinical variables—age, neoadjuvant treatment, and adjuvant treatment—as significant predictors of progression (all p < 0.05), alongside five radiomics features. The clinical model achieved an area under the curve (AUC) of 0.69 (95% CI, 0.60–0.77), with a correct classification rate of 65.8%. In comparison, the radiomics model demonstrated an AUC of 0.65 (95% CI, 0.53–0.73) and a correct classification rate of 63.4%. The combined model, which integrated both radiomics and clinical features, yielded an AUC of 0.73 (95% CI, 0.65–0.81), improving the correct classification rate to 70%.