Skeletal Muscle Metastasis from Non-small Cell Lung Cancer

Purpose: Skeletal muscle metastases (SMM) from non-small cell lung cancer (NSCLC) are rarely encountered in clinical practice. The prognosis and the adequate treatment are not known. The aim of the study was to report our experience and to make an extensive literature research concerning SMM. Patients and Methods: In our unit, we identified 16 patients with SMM in a 10-year period. The source of our literature search (English and French language) was the international MEDLINE database, and it exhausted all cited publications. Results: We found 114 cases in the international literature (follow-up period mentioned in 72 cases). Pain was the most frequent symptom (83%). A mass was palpable in 78% of cases. The diagnosis was obtained by either fine needle/surgical biopsy or wide exeresis. The 5-year survival time was 11.5% with a median survival of 6 months. The 5-year Survival rates: number of SMM - single versus multiple (13.6% [67 patients] versus 0% [21 patients]; p = 0.0022); disease-free interval (DFI) >6 months versus DFI :56 months (16.9% [18 patients] versus 9.1% [70 patients]; p = 0.0458). We built three groups of prognostic significance: group 1: DFI >6 months and single metastasis; group II: DFI >6 months or single metastasis; and group III: DFI :56 months and multiple metastasis. The 5-year survival rates were: group 1 (14 patients): group II (57 patients):group III (17 patients) = 28%:6%:0% (p = 0.0000), and the median survival was 19:9:4 months. Conclusion: The presence of SMM suggests an aggressive disease. Selection of patients for a local treatment is an important factor that determines survival. The ideal patient had a unique metachronous metastasic deposit that can be treated by surgery.