Abstract
Purpose
Evaluate the demographics, stages and outcomes in Myxoid (ML) and Round Cell liposarcoma (RCL). Establish the incidence of local recurrence and metastases. Outline the use and benefits of radiotherapy and chemotherapy. Provide guidelines for future management of these rare tumors
Method
Multicentric retrospective study of 421 cases of MRCLS primarily managed by multidisciplinary sarcoma teams in Canada. Data were collected in each centers through a standardized database and statistically analysed.
Results
There were 247 males (59%) Age ranged from 14 to 88 years old (avg: 46 yrs) and the average follow-up was 5.9 yrs (range: 1 mo–21.3 yrs). Tumor volume averaged 745 cc (range: 1.5–14580 cc). The proximal lower limb, including the thigh, the buttock and the inguinal region, was the location in 314 cases (75%). Tumors were deep in 81%. On histology 305 patients were classified as pure myxoid liposarcoma, 87 had mixed myxoid/round cell histology (≥ 5% round cell content)and 19 were pure round cells only. AJCC staging were Ia: 44, Ib: 114, IIa: 115, IIb: 57, IIc: 2, III: 56, IV: 9, unknown: 24. Radiotherapy was given to 310 pts and chemotherapy to 26 pts as part of initial management. 419 underwent surgery (407 limb salvage and 12 amputations) Margins were R0 in 309, R1 in 94 and R2 in 15 patients. Overall 10 yrs local control rate was 92% and no differences were recorded between ML and RCL. Radiotherapy was significant in preventing local relapse (p= 0.03) but did not impact survival. Metastatic disease was recorded in 82 patients (19%). Chemotherapy did not prevent metastatic occurrence and survival was statistically worse for the chemotherapy group (p= 0.01). Location of first metastasis was often multiple (29), followed by lung or soft tissue (14 each), retroperitoneum (12) and bone (10). Thirty-four patients had bone involvement with spine involved in 27. The 5 and 10 yrs metastatic free survival were respectively 84 and 73% for ML and 73 and 49% for RCL (p= 0.003). Latest disease status were: 323 alive with no evidence of disease, 27 alive with disease, 8 alive with unknown status, 52 deadfrom tumor and 11 dead from other causes.
Conclusion
Myxoid and Round cell Liposarcoma present different prognoses. Metastatic disease at the time of diagnosis is an unusual event. Local control is good but radiotherapy decreased the incidence of local relapse. The effectiveness of chemotherapy remains to be established for round cell liposarcoma. New staging stategies need to be identified to account for the unusual metastatic pattern of these sarcoma.
