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Background Photon involved-field radiation therapy (IFRT), the standard for locally advanced non-small cell lung cancer (LA-NSCLC), results in favorable outcomes without increased isolated nodal failures, perhaps from scattered dose to elective nodal stations. Given the high conformality of intensity-modulated proton therapy (IMPT), proton IFRT could increase nodal failures. We investigated the feasibility of IMPT for elective nodal irradiation (ENI) in LA-NSCLC. Materials and Methods IMPT IFRT plans were generated to the same total dose of 66.6–72 Gy received by 20 LA-NSCLC patients treated with photon IFRT. IMPT ENI plans were generated to 46 CGE to elective nodal (EN) planning treatment volumes (PTV) plus 24 CGE to involved field (IF)-PTVs. Results Proton IFRT and ENI both improved D95 involved field (IF)-PTV coverage by 4% (p<0.01) compared to photon IFRT. All evaluated dosimetric parameters improved significantly with both proton plans. Lung V20 and mean lung dose decreased 18% (p<0.01) and 36% (p<0.01), respectively, with proton IFRT and 11% (p=0.03) and 26% (p<0.01) with ENI. Mean esophagus dose decreased 16% with IFRT and 12% with ENI; heart V25 decreased 63% with both (all p<0.01). Conclusions This study demonstrates the feasibility of IMPT for LA-NSCLC ENI. Potential decreased toxicity indicates IMPT could allow ENI while maintaining a favorable therapeutic ratio compared to photon IFRT.

Purpose-Photon radiotherapy has been standard adjuvant treatment for stage I seminoma. Single dose carboplatin and observation have emerged as alternative options due to concerns of acute toxicities and secondary malignancies from radiation. In this IRB-approved study, we compare photon and proton radiotherapy for stage I seminoma and predict rates of excess secondary malignancies for both treatment modalities.Methods and Material-CT images from 10 consecutive patients with stage I seminoma were used to quantify dosimetric differences between photon and proton therapy. Structures reported to be at increased risk for secondary malignancies and in-field critical structures were contoured. Reported models of organ-specific radiation-induced cancer incidence rates based on organ equivalent dose were used to determine the excess absolute risk of secondary malignancies. Calculated values were compared with tumor registry reports of excess secondary malignancies among testicular cancer survivors.Results-Photon and proton plans provided comparable target volume coverage. Proton plans delivered significantly lower mean doses to all examined normal tissues except the kidneys. The greatest absolute reduction in mean dose was observed for the stomach (119cGy vs. 768cGy, p<0.0001). Significantly more excess secondary cancers per 10,000 patients/yr were predicted with photons compared with protons for the stomach (4.11; 95% CI=3.22-5.01), large bowel (0.81; CI=0.39-1.01), and bladder (0.03; CI=0.01-0.58), while no difference was demonstrated for the pancreas (0.02; CI=−0.01-0.06). Conflict of Interest: nonePublisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. NIH Public Access Author ManuscriptInt J Radiat Oncol Biol Phys. Author manuscript; available in PMC 2013 January 1. Conclusions-For patients with stage I seminoma, proton therapy reduced the predicted secondary cancer risk compared with photon therapy. We predict a reduction of one additional secondary cancer for every 50 patients with a life expectancy of 40 years from the time of radiation treated with protons instead of photons. Protons also allowed significant sparing of most critical structures examined and warrant further study for patients with seminoma to decrease radiation-induced toxicity.

There are several proposed mechanisms of spread of a primary tumor to the leptomeninges. 20,22,41 FIG 3. Anatomy of the major subarachnoid cisterns. Note that the superior and inferior cerebellopontine cisterns are lateral to this midline sagittal projection. MSKCC, Medical Graphics and Photography, 2006. (Color version of figure is available online.)

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Background There has been an increase in the utilization of single-fraction stereotactic body radiation therapy (SBRT) to treat thoracic structures, but there have been few reports describing toxicity outcomes with this treatment. Methods We evaluated 119 sites (114 patients) with no prior history of thoracic radiation were treated from 10/1/2003 to 10/27/2008 with single-fraction SBRT to thoracic structures. The median dose to the gross tumor volume was 2400 cGy (range 1800–2400 cGy), as was the median dose to the planning target volume (range 1600–2400 cGy). A detailed review of thoracic toxicities was performed to include pneumonitis or Grade 2 or higher esophageal and bronchial toxicity. In addition, we retrospectively contoured the esophagus and bronchus of 48 patients treated in 2004–2005, prior to the establishment of dose constraints to determine the range of doses that these structures received. Results Of the contoured patients, the median dose to the hottest 1 cc (D1cc) of the esophagus was 1250 cGy (range 158–2572 cGy). The median bronchial D1cc was 1101 cGy (range 260–2211 cGy). At a median follow-up of 11.6 months, there were seven Grade 2 or higher esophageal toxicities, including one Grade 3 and one Grade 4 toxicities. There were two bronchial toxicities, one Grade 2 and one Grade 3. There were no cases of pneumonitis. Conclusions High-dose single-fraction SBRT is well tolerated to the thoracic region, with most patients tolerating high doses to central structures without significant toxicity.

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