Characterized by a wide histological spectrum, myxofibrosarcoma ranges from deceptively bland-appearing lesions to frankly pleomorphic sarcomas, representing a suitable model to elucidate the molecular aberrations in multistep disease progression. Using genome-wide array comparative genomic hybridization, we have profiled DNA copy number alterations in myxofibrosarcoma samples and cell lines in coupled with expression profiling data and identified prominent SKP2 amplification on 5p, frequent homozygous deletion of MTAP on 9p, as well as loss expression of ASS1, a candidate tumor suppressor. As a predominant driving mechanism, SKP2 gene amplification was detected in one-third of cases in independent cohort validation and associated with SKP2 immunohistochemical expression, adverse prognosticators, and worse patient survival. Besides the classical attribute in promoting cell proliferation and tumor growth, we have confirmed the pro-metastatic oncogenic function of SKP2 and identified differentially expressed motility-promoting genes as its potential mediators, including ITGB2, ACTN1, IGF1, and ENAH. Since MTAP and ASS1 are key enzymes in either salvage pathway of nucleologenesis and amino acid biosynthesis, their deficiency suggests alterations involving metabolic homeostasis is important in sarcomagenesis. We in our studies not only validated their deletion and/or epigenetic silencing in myxofibrosaroma, evaluating the therapeutic responses of L-alanosine and ADI-PEG20 in MTAP or ASS1 deficient cells in vitro and in vivo, but also confirmed their tumor suppressor functions with special focus on tumor angiogenesis. Our study provides further insight into the molecular pathogenesis in tumor progression and highlights the prognostic, biological, and potential therapeutic relevance in myxofibrosarcoma.

INTRODUÇÃO: O mixofibrossarcoma (MFS) é um dos mais frequentes sarcomas de partes moles (SPM) em idosos que afeta principalmente as extremidades. Historicamente, é um grupo de tumores heterogêneos. Clinicamente está caracterizado por apresentar uma alta incidência de recorrência local (RL) e um conhecimento limitado sobre a sua capacidade de metástase. O índice de RL após a ressecção cirúrgica é relativamente maior quando comparado com outros SPM. Não existe um consenso em como identificar os pacientes com maior risco. O objetivo deste estudo foi analisar os fatores de prognóstico dos pacientes diagnosticados com MFS em uma instituição única. MÉTODOS: Foram analisados retrospectivamente os prontuários de 75 pacientes com diagnóstico confirmado de MFS nas extremidades, que foram submetidos a tratamento cirúrgico, nos últimos 25 anos. Comparamos idade, sexo, tamanho e localização do tumor, grau histológico segundo a Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) e o estádio segundo a American Joint Committee on Cancer (AJCC). A média de idade foi 49,7 anos. A localização foi: membro superior (25,4%), membro inferior (66,6%) e pelve (8%). Os pacientes apresentaram baixo, intermediário e alto grau, em: 29,3%, 24% e 46,7% dos tumores, respectivamente. Pelo tamanho foram categorizados em: =/< 5 cm (13,3%), > 5 e <10 cm (42,7%), > 10 e <15 cm (9%) e =/> 15 cm (18,7%). Em total, 26,7% receberam radioterapia pós-operatória. As margens foram livres em 76% e comprometidas em 24%. A análise da regressão de Cox bivariada foi utilizada para determinar as associações entre os fatores clínicos e de tratamento com a RL. RESULTADOS: O tempo médio de seguimento foi 30.7 meses. O 26,7% dos pacientes apresentaram RL. Metástase foi reportada em 27 (36%) pacientes. O local mais comum de metástase foi: pulmão (92,6%) e gânglios linfáticos (18,5%). O tempo médio de sobrevida dos pacientes com metástase foi 21,2 meses. Os fatores preditivos para RL foram: margens comprometidas (hazard ratio 5.47, 95% intervalo de confiança, 2.23-13.40, P < 0.001) e metástase (hazard ratio 10.24, 95% intervalo de confiança, 3.53-26.68, P < 0.001). Os fatores preditivos da sobrevida livre de RL foram: grau histológico, margens comprometidas (hazard ratio 3.18, 95% intervalo de confiança, 1.51-6.70, P =0.001), e metástase (hazard ratio 15.23, 95% intervalo de confiança, 5.57-41.61, P= 0.001). Os fatores preditivos de sobrevida em geral foram: RL (hazard ratio 5.13, 95% intervalo de confiança, 2.15-12.24, P < 0.001), e metástase (hazard ratio 540.97, 95% intervalo de confiança, 5.04-58112.03, P < 0.001). CONCLUSÃO: As margens cirúrgicas comprometidas e a metástase estão diretamente associadas com a RL. O grau histológico do tumor, as margens comprometidas, a RL e a metástase, são fatores de pior prognóstico no MFS / BACKGROUND AND AIMS: Myxofibrosarcoma (MFS) is one of the most common soft tissue sarcomas (STS) in elderly patients and it primarily affects the extremities. They are a historically heterogeneous group of tumors. The clinical course of MFS is characterized by a high incidence of local recurrences (LR), but knowledge about distant metastasis is sparse. MFS is reported to have a higher risk of LR following definitive surgical excision relative to other STS. There is no agreement on how to identify patients at major risk. The objectives of this study were to analyze the prognostic factors and outcomes of patients with MFS treated at a single institution. METHODS: We retrospectively reviewed the records of 75 patients with pathologically confirmed MFS of the extremities who underwent surgery in the last 25 years. We compared the age, sex, tumor size and location, Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) grade and the American Joint Committee on Cancer (AJCC) stage. Median age was 49.7 years (range, 1 to 88 y). Site of disease was: upper extremity (25.4%), lower extremity (66.6%) and pelvic (8%). Patients had low, intermediate and high-grade, in: 29.3%, 24% and 46.7% of tumors, respectively. Tumors were categorized as =/< 5 cm (13.3%), > 5 and < 10 cm (42.7%), > 10 and < 15 cm (9%) and =/> 15 cm (18.7%). In total, 26.7% received postoperative radiotherapy. All patients underwent surgery. Margins were negative in 76% and positive in 24%. Bivariate Cox regression analysis was utilized to determine associations between clinical and treatment factors with LR. RESULTS: Median follow-up time was 30.7 months (range, 1.8 to 383.8 m). We found a 26.7% of LR. Distant metastasis was reported in 27 (36%) patients. The most common sites of metastasis were: lung (92.6%) and lymph nodes (18.5%). The overall survival rate in patients with metastasis was 21.2 months (range, 4.8 to 114.8 m). Predictors of LR were: positive margins (hazard ratio 5.47, 95% confidence interval, 2.23-13.40, P < 0.001) and distant metastasis (hazard ratio 10.24, 95% confidence interval, 3.53-26.68, P < 0.001). Predictors of overall survival free of LR were: grade, positive margins (hazard ratio 3.18, 95% confidence interval, 1.51-6.70, P =0.001), and distant metastasis (hazard ratio 15.23, 95% confidence interval, 5.57-41.61, P= 0.001). Predictors of overall survival were grade, LR (hazard ratio 5.13, 95% confidence interval, 2.15-12.24, P < 0.001), and distant metastasis (hazard ratio 540.97, 95% confidence interval, 5.04-58112.03, P < 0.001). CONCLUSION: In this institutional series of MFS, positive margins and distant metastasis were significantly associated with a higher risk of LR. Tumor grade, LR, positive margins and distant metastases were significant predictors of overall survival poor prognosis

INTRODUÇÃO: O mixofibrossarcoma (MFS) é um dos mais frequentes sarcomas de partes moles (SPM) em idosos que afeta principalmente as extremidades. Historicamente, é um grupo de tumores heterogêneos. Clinicamente está caracterizado por apresentar uma alta incidência de recorrência local (RL) e um conhecimento limitado sobre a sua capacidade de metástase. O índice de RL após a ressecção cirúrgica é relativamente maior quando comparado com outros SPM. Não existe um consenso em como identificar os pacientes com maior risco. O objetivo deste estudo foi analisar os fatores de prognóstico dos pacientes diagnosticados com MFS em uma instituição única. MÉTODOS: Foram analisados retrospectivamente os prontuários de 75 pacientes com diagnóstico confirmado de MFS nas extremidades, que foram submetidos a tratamento cirúrgico, nos últimos 25 anos. Comparamos idade, sexo, tamanho e localização do tumor, grau histológico segundo a Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) e o estádio segundo a American Joint Committee on Cancer (AJCC). A média de idade foi 49,7 anos. A localização foi: membro superior (25,4%), membro inferior (66,6%) e pelve (8%). Os pacientes apresentaram baixo, intermediário e alto grau, em: 29,3%, 24% e 46,7% dos tumores, respectivamente. Pelo tamanho foram categorizados em: =/< 5 cm (13,3%), > 5 e <10 cm (42,7%), > 10 e <15 cm (9%) e =/> 15 cm (18,7%). Em total, 26,7% receberam radioterapia pós-operatória. As margens foram livres em 76% e comprometidas em 24%. A análise da regressão de Cox bivariada foi utilizada para determinar as associações entre os fatores clínicos e de tratamento com a RL. RESULTADOS: O tempo médio de seguimento foi 30.7 meses. O 26,7% dos pacientes apresentaram RL. Metástase foi reportada em 27 (36%) pacientes. O local mais comum de metástase foi: pulmão (92,6%) e gânglios linfáticos (18,5%). O tempo médio de sobrevida dos pacientes com metástase foi 21,2 meses. Os fatores preditivos para RL foram: margens comprometidas (hazard ratio 5.47, 95% intervalo de confiança, 2.23-13.40, P < 0.001) e metástase (hazard ratio 10.24, 95% intervalo de confiança, 3.53-26.68, P < 0.001). Os fatores preditivos da sobrevida livre de RL foram: grau histológico, margens comprometidas (hazard ratio 3.18, 95% intervalo de confiança, 1.51-6.70, P =0.001), e metástase (hazard ratio 15.23, 95% intervalo de confiança, 5.57-41.61, P= 0.001). Os fatores preditivos de sobrevida em geral foram: RL (hazard ratio 5.13, 95% intervalo de confiança, 2.15-12.24, P < 0.001), e metástase (hazard ratio 540.97, 95% intervalo de confiança, 5.04-58112.03, P < 0.001). CONCLUSÃO: As margens cirúrgicas comprometidas e a metástase estão diretamente associadas com a RL. O grau histológico do tumor, as margens comprometidas, a RL e a metástase, são fatores de pior prognóstico no MFS / BACKGROUND AND AIMS: Myxofibrosarcoma (MFS) is one of the most common soft tissue sarcomas (STS) in elderly patients and it primarily affects the extremities. They are a historically heterogeneous group of tumors. The clinical course of MFS is characterized by a high incidence of local recurrences (LR), but knowledge about distant metastasis is sparse. MFS is reported to have a higher risk of LR following definitive surgical excision relative to other STS. There is no agreement on how to identify patients at major risk. The objectives of this study were to analyze the prognostic factors and outcomes of patients with MFS treated at a single institution. METHODS: We retrospectively reviewed the records of 75 patients with pathologically confirmed MFS of the extremities who underwent surgery in the last 25 years. We compared the age, sex, tumor size and location, Fédération Nationale des Centres de Lutte Contre le Cancer (FNCLCC) grade and the American Joint Committee on Cancer (AJCC) stage. Median age was 49.7 years (range, 1 to 88 y). Site of disease was: upper extremity (25.4%), lower extremity (66.6%) and pelvic (8%). Patients had low, intermediate and high-grade, in: 29.3%, 24% and 46.7% of tumors, respectively. Tumors were categorized as =/< 5 cm (13.3%), > 5 and < 10 cm (42.7%), > 10 and < 15 cm (9%) and =/> 15 cm (18.7%). In total, 26.7% received postoperative radiotherapy. All patients underwent surgery. Margins were negative in 76% and positive in 24%. Bivariate Cox regression analysis was utilized to determine associations between clinical and treatment factors with LR. RESULTS: Median follow-up time was 30.7 months (range, 1.8 to 383.8 m). We found a 26.7% of LR. Distant metastasis was reported in 27 (36%) patients. The most common sites of metastasis were: lung (92.6%) and lymph nodes (18.5%). The overall survival rate in patients with metastasis was 21.2 months (range, 4.8 to 114.8 m). Predictors of LR were: positive margins (hazard ratio 5.47, 95% confidence interval, 2.23-13.40, P < 0.001) and distant metastasis (hazard ratio 10.24, 95% confidence interval, 3.53-26.68, P < 0.001). Predictors of overall survival free of LR were: grade, positive margins (hazard ratio 3.18, 95% confidence interval, 1.51-6.70, P =0.001), and distant metastasis (hazard ratio 15.23, 95% confidence interval, 5.57-41.61, P= 0.001). Predictors of overall survival were grade, LR (hazard ratio 5.13, 95% confidence interval, 2.15-12.24, P < 0.001), and distant metastasis (hazard ratio 540.97, 95% confidence interval, 5.04-58112.03, P < 0.001). CONCLUSION: In this institutional series of MFS, positive margins and distant metastasis were significantly associated with a higher risk of LR. Tumor grade, LR, positive margins and distant metastases were significant predictors of overall survival poor prognosis