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Introduction We investigated safety, efficacy, and recurrence after postoperative hemithoracic intensity-modulated radiation therapy (IMRT) in patients with malignant pleural mesothelioma (MPM)treated with extrapleural pneumonectomy (EPP) during the past decade at a single institution. Methods In 2001–2011, 136 consecutive patients with MPM underwent EPP with planned adjuvant IMRT. Eighty-six patients (64%) underwent hemithoracic IMRT; the rest were not eligible because of postoperative complications, disease progression, or poor performance status. We assessed toxicity, survival, and patterns of failure in these 86 patients. Toxicity was scored with the Common Terminology Criteria for Adverse Events v4.0; survival outcomes were estimated with the Kaplan-Meier method; and local-regional patterns of failure were classified as in-field, marginal, or out-of-field. Risk factors related to survival were identified by univariate and multivariate Cox regression analysis. Results Median overall survival time for all 86 patients was 14.7 months. Rates of grade ≥ 3 toxicity were skin 17%, lung 12%, heart 2.3%, and gastrointestinal toxicity 16%. Five patients experienced grade 5 pulmonary toxicity. Rates of local-regional recurrence-free survival, distant metastasis-free survival (DMFS), and overall survival (OS) were 88%, 55%, and 55% at 1 year and 71%, 40%, and 32% at 2 years. On multivariate analysis, pretreatment forced expiratory volume in 1 second (FEV1), non-epithelioid histology, and nodal status were associated with DMFS and OS. Conclusion IMRT after EPP is associated with low rates of local-regional recurrence, though some patients experience life-threatening lung toxicity. Tumor histology and nodal status can be helpful for identifying patients for this aggressive treatment.

Purpose Desmoplastic small round cell tumor (DSCRT) is an uncommon pediatric tumor with a poor prognosis. Aggressive multimodality therapy is the current treatment approach, however treatment toxicity is of concern. We report our results with whole abdominopelvic intensity-modulated radiation therapy (WAP-IMRT) as a component of multimodality therapy for DSCRT at a single institution. Materials/Methods Medical records of all patients with DSCRT who received WAP-IMRT as part of definitive treatment at MD Anderson (2006-2010) were identified and reviewed. Results Eight patients with DSRCT received WAP-IMRT with a median follow-up of 15.2 months. All patients received multiple courses of chemotherapy followed by surgical debulking of intra-abdominal disease; seven also had intraoperative hyperthermic cisplatin. WAP-IMRT was delivered to a total dose of 30 Gy post-operatively; four patients received a simultaneous boost (6-10 Gy) to sites of gross residual disease. Seven patients received concurrent chemotherapy during WAP-IMRT. No RTOG grade 4 nausea, vomiting, or diarrhea occurred during RT. Red cell transfusions were given to two patients to maintain hemoglobin levels of greater than 10 g/dL. Grade 4 cytopenia requiring growth factor support occurred in only one patient; no other significant cytopenias were noted. WAP-IMRT resulted in 25% lower radiation doses to the lumbosacral vertebral bodies and pelvic bones than conventional RT plans. The median time to local or distant failure after WAP-IMRT was 8.73 months in seven patients. One patient who had completed RT 20 months before the last follow-up remains alive without evidence of disease. Five patients (63%) experienced treatment failure in the abdomen. Distant failure occurred in three patients (37.5%). Conclusions WAP-IMRT with concurrent radiosensitizing chemotherapy was well tolerated after aggressive surgery for DSCRT. Enhanced bone sparing with IMRT probably accounts for the low hematologic toxicity (vs. conventional WAP RT). This modality should be considered as an additional local-regional control option for DSRCT.

The purpose of this work is to estimate the uncertainty in the manual contouring of normal anatomical structures. The heart, esophagus, and spinal cord were contoured manually on six sets of computed tomography images by six dosimetrists whose experience ranged from 1 year to over 15 years. To determine the differences between inter‐ and intraobserver variations, each data set was contoured by one of the dosimetrists five times and once each by the five other dosimetrists. The magnitude of the discrepancies in delineating the contours was assessed. Intradosimetrist contouring discrepancies were as follows: esophagus, average 0.3 cm and maximum 2.9 cm; heart, average 0.5 cm and maximum 7.6 cm; and spinal cord, average 0.1 cm and maximum 0.7 cm. Interdosimetrist contouring discrepancies were as follows: esophagus, average 0.4 cm and maximum 3.1 cm; heart, average 0.7 cm and maximum 8.1 cm; and spinal cord, average 0.2 cm and maximum 0.9 cm. Significant discrepancies can occur when normal anatomic structures are contoured manually. Interdosimetrist discrepancies are typically slightly greater than intradosimetrist discrepancies. The magnitude of the discrepancies does not appear to be correlated to the experience of the dosimetrist. © 2003 American College of Medical Physics.PACS number(s): 87.53.–j, 87.66.–a