Incidence, risk factors, and prognostic impact of regional lymph node metastasis in bone sarcoma: a population-based cohort study.

BACKGROUND

This study aimed to investigate the risk factors and prognostic impact of regional lymph node metastasis (RLNM) in patients with bone sarcoma.

METHODS

This retrospective study analyzed data from a Japanese registry of patients with bone sarcoma (2006-19). Disease-specific overall survival was estimated using the Kaplan-Meier method. A Cox regression model was used to identify risk factors for RLNM and prognostic factors.

RESULTS

Among 5064 patients, 157 (3.1%) had RLNM. The incidence varied by histological subtype: 7.6% in Ewing sarcoma, 3.1% in osteosarcoma, 1.6% in chondrosarcoma, and 5.2% in undifferentiated pleomorphic sarcoma. Higher rates were observed in rare subtypes, including mesenchymal chondrosarcoma (12.9%) and dedifferentiated chondrosarcomas (10.3%). Risk factors for RLNM included older age, tumor size (>8 cm) (P = .02), distant metastasis at diagnosis (P < .0001), skip metastasis (P < .0001), and histological subtype (e.g. Ewing sarcoma and dedifferentiated chondrosarcoma). RLNM was associated with poor prognosis (HR 1.69, 95% CI: 1.35-2.1, P < .0001), with isolated RLNM conferring survival outcomes equivalent to those with distant metastasis. Among RLNM cases, skip metastasis was the only significant independent predictor of poor prognosis (HR 2.41, 95% CI: 1.35-4.30, P = .003).

CONCLUSIONS

The incidence of RLNM in bone sarcomas varies by histological subtype. Risk factors include older age, tumor size, distant metastasis, skip metastasis, and histological subtype. Isolated RLNM has a prognosis comparable to that of distant metastases, and skip metastasis is a significant negative prognostic factor.