| Part I:The role of adjuvant radiotherapy in the treatment of patients with primary soft tissue sarcomaPurpose:To assess the impact of adjuvant radiotherapy on the patients with primary soft tissue sarcoma (STS) who underwent conservative surgery. The prognostic factors were also identified.Methods and materials:We retrospectively reviewed203patients with the first five most common subtypes of STS in Cancer Hospital of Fudan University sarcoma database during the time period of January2000to July2010. The histologic subtypes mainly included rhabdomyosarcoma, malignant fibrous histiocytoma, liposarcoma, synovial sarcoma and fibrosarcoma. All patients received conservative surgery for curative purpose and76patients (37.4%) received post-operative radiotherapy. Prognostic factors for survival were identified by multivariate analysis. Survival was calculated using the Kaplan-Meier method and the log-rank test was used to assess statistical difference.Result:The median follow-up was47months (7months～132months). The5-year overall survival, local failure-free survival, distant metastasis-free survival and sarcoma-specific survival were69%,69%,68% and72%, respectively. Tumor histology, size, margin status and radiotherapy were significantly independent prognostic factors for OS. RT had significantly reduced the risk of mortality compared with no RT (Hazard ratio [HR]=0.489,95% confidence interval [CI],0.266～0.897, P=0.021), with a5-year OS of74.8% and65%, respectively. The radiotherapy was also significantly associated with improved LFFS, while had no impact on DMFS. The subgroup analysis showed that radiotherapy improved the overall survival in patients with liposarcoma and local failure-free survival in patients with positive margin, Grade Ⅱ and tumor size>5cm.Conclusion:Radiotherapy can not only reduce the risk of local recurrence, but also improve OS in patients with primary STS. Tumor histology, size, margin status and radiotherapy were significantly independent prognostic factors for OS. Part II:Evaluation the difference of dose distribution between conventional fractionation and hypofractionation radiation plans in patients with retroperitoneal soft tissue sarcoma.Purpose:To compare the dose distribution between conventional fractionation and hypofractionation intensity modulated radiotherapy (IMRT) in patients with retroperitoneal soft tissue sarcoma (RPS), who received radiotherapy.Methods and materials:Between August2011and February2012,10RPS patients were included in this study. Both conventionally fractionated (50Gy in25fractions) and hypofractionated (35.4Gy in8fractions) IMRT plans were made for every patient. After converting the dose to EQD2, the dose delivered to the organs at risk and the conformity index (CI) were compared. NTCP model was used to compare the toxicity of organ at risk between hypofractionation and conventional fractionation schedules.Results:The CI was0.69for both conventionally fractionated and hypofractionated plans. The hypofractionated plans provided significant reductions in the mean dose, high-dose irradiated volume and low-dose irradiated volume of bowel cavity compared to conventionally fractionated plan, which also reduced the mean dose of stomach and contralateral kidney received. However, the maximal dose delivered to the spinal cord increased from26.28to28.35Gy with hypofractionated plans. The NTCP model revealed that the hypofractionated plans significantly reduced the toxicity of bowel cavity (0.460%Vs0.573%, P=0.003) and stomach (4.856%Vs5.058%, P=0.004).Conclusion:Compared to conventionally fractionated plan, the hypofractionated plans reduced the dose of bowel cavity and stomach receiving. The NTCP model revealed that the hypofractionated plans significantly reduced the toxicity of bowel cavity and stomach. Clinical follow-up is needed to confirm the toxicities to organs at risk when the hypofractionated plans administer. |
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