with PET avid paraaortic, pelvic, or inguinal lymph nodes were treated with IMRT with simultaneous integrated boost between 2009 and 2013. Median dose to ...
S504
International Journal of Radiation Oncology Biology Physics
Results: IPSA plans using only surface-based optimization objectives for PTV produced consistently acceptable plans with the highest conformity and homogeneity, and relatively high PTV D90 and V100 compared to volume-based objectives. They also created plans with the lowest vaginal mucosa doses, PTV hot spots and low bladder and rectal doses. There are more optimization settings within the HIPO module and determination of settings producing the most consistent results was difficult. A very low weighting for normal tissue was required (0.001) to consistently generate a V100 that was better than surface-based IPSA, however, PTV hot spots were also larger. HIPO showed a wider variation in dosimetry with relatively small changes in constraints. The ability to ’lock’ applicator channels in HIPO, effectively removing them from the optimization algorithm, allowed for better customization of a plan in individual circumstances. Conclusions: Optimization for intracavitary multi-channel vaginal cylinders can be achieved through both IPSA and HIPO. A dose distribution closer to the ’ideal’ is consistently produced for patients using surfacebased IPSA constraints. Plans generated using HIPO have an increased risk of hot spots, however, there is greater opportunity for refining dosimetry in individual circumstances if required. Author Disclosure: C. Lapuz: None. P. Simpson: None. C. Dempsey: None.
control of 95% with an acceptable toxicity profile. We plan to study this regimen further in a prospective single institution study. Author Disclosure: M.A. Mezera: A. Employee; Resident, University of Louisville Hospital, Department of Radiation Oncology. M.N. ElGhamry: A. Employee; Assistant Professor, University of Louisville Hospital, Department of Radiation Oncology. P. Royalty; UpToDate.
2741 Intensity Modulated Radiation Therapy Utilizing Dose-Escalated Integrated Simultaneous Boost to PET Avid Gross Nodal Disease in Gynecologic Malignancies: Analysis of Disease Response and Toxicity M.A. Mezera and M.N. El-Ghamry; University of Louisville, Brown Cancer Center, Louisville, KY Purpose/Objective(s): Regional nodal irradiation improves survival and reduces metastases in locally advanced gynecologic cancers. However, typical doses of 45-50 Gy have been shown to be inadequate to control gross nodal disease. At our institution, we utilize a regimen of IMRT to 4550.4 Gy at 1.8 Gy/fraction to elective nodal volumes with simultaneous integrated boost up to 63 Gy at 2.25 Gy/fraction to PET avid gross nodal disease. The purpose of this study is to evaluate toxicity and tumor control using this dose-escalated regimen. Materials/Methods: Twenty patients with gynecologic cancers presenting with PET avid paraaortic, pelvic, or inguinal lymph nodes were treated with IMRT with simultaneous integrated boost between 2009 and 2013. Median dose to regional lymphatics was 45 Gy (range, 41.4-50.4 Gy) at 1.8 Gy/fraction. Median simultaneous integrated boost dose was 56.25 Gy (range, 48-63 Gy) at 2-2.25 Gy/fraction. 13 patients received concurrent chemotherapy. 12 patients received brachytherapy. Toxicity was evaluated throughout treatment and at routine follow up visits. Disease recurrence was identified by imaging and/or biopsy. Results: Median follow up from completion of treatment was 8.9 months (range, 0.97-46.97 months). Local control within the high dose integrated boost region was 95%. A single patient experienced local failure in the high dose region 7.03 months after completion of treatment. This patient had the largest volume of gross nodal disease in the cohort (358.2 cm3). She received a relatively low boost dose of 55 Gy. Her in-field recurrence was salvaged by additional radiotherapy. She later developed distant metastases, but was still alive at last available follow-up, 38 months from completion of treatment. 3 patients failed in the elective nodal basin but outside the integrated boost volume; 2 of these patients also developed metastases. 3 patients failed distantly only. 4 patients died of metastatic disease, and 1 of unknown causes, at a median 6.37 months from completion of treatment (range, 3-10.5 months). Treatment was well tolerated. The most common acute toxicities were grade I-II diarrhea (n Z 16) and grade I-II nausea (n Z 9). One patient developed grade III dermatitis. There were no grade IV-V acute toxicities. Late toxicity was limited, with 45% of patients reporting no late toxicity. All observed late toxicities were complications of brachytherapy that occurred outside the high dose integrated boost region. Conclusions: Although follow up is relatively short (median 8.9 months), dose-escalated simultaneous integrated boost resulted in excellent local
2742 Stereotactic Body Radiation Therapy in Recurrent, Persistent, or Oligometastatic Gynecological Tumors S. Baliga,1 E.F. Crandley,2 H. Lomas,3 K.M. Richardson,1 K. Spencer,1 N. Bennion,4 H. El Aldo Mikdachi,1 W.P. Irvin,1 and C. Kersh5; 1Riverside Regional Medical Center, Newport News, VA, 2University of Virginia, Charlotesville, VA, 3Virginia Commonwealth University, Richmond, FL, 4 University of Nebrasaka, Omaha, NE, 5UVA/Riverside Radiosurgery Center, Newport News, VA Purpose/Objective(s): Stereotactic Body Radiation Therapy (SBRT) is well tolerated and provides local-regional control in a number of primary malignancies. The role of SBRT in recurrent, persistent, or metastatic gynecological tumors is not well studied. We reviewed our institutional experience with SBRT in patients with gynecological malignancies treated with SBRT for pelvic or extra-pelvic disease. Materials/Methods: We performed a retrospective review of 52 patients treated between January 2007 and December 2013 with SBRT for recurrent, persistent, or oligometastatic gynecological tumors including Ovarian (n Z 19), Endometrial (n Z 15), Cervical/Vaginal (n Z 16), and Vulvar (n Z 2) carcinoma. The median SBRT dose was 24 Gy delivered in a median of 3 fractions. Dose was prescribed to a non-uniform ITV based on margins constructed from a 4D CT scan to account for tumor motion. The treatment planning techniques included non-coplanar static aperture ARCs and non-coplanar static fields. IMRT and VMAT planning techniques are considered. Treatments were delivered using a robotic stereotactic radiosurgical approach with a beam modulator. The Kaplan Meier Product Estimator was used to assess Local Control (LC) and Overall Survival (OS). Toxicity was scored using the CTCAE v 4.0 system. Radiological imaging and clinical follow up were performed at 3-month intervals to assess treatment response. Results: We identified 79 tumors in 52 patients with a mean follow up of 13 months (range 1.7-47 months). The most common indications for SBRT were lymph node metastasis (n Z 20), recurrent disease (n Z 15), persistent disease (n Z 8), lung metastasis (n Z 12), and liver metastasis (n Z 11). Median tumor size was 2.1 cm. The 1- and 3-year LC were 81% and 70% respectively. 25% of lesions demonstrated complete response, 34% a partial response, and 14% with stable disease. 27% of patients had disease progression with a mean time to progression of 7 months. 1 yearLC for extrapelvic versus pelvic disease was 93% vs 76% respectively.2 year-OS was 52% in patients with extrapelvic disease vs 13% in patients with pelvic disease. There was minimal toxicity with only 5.7% of patients reporting grade 2 cystitis and 4% who developed grade 3 urethral strictures. Conclusions: SBRT offers a high rate of local control with low incidence of acute or chronic toxicity and provides effective salvage therapy for pelvic and extra-pelvic gynecological tumors. Author Disclosure: S. Baliga: None. E.F. Crandley: None. H. Lomas: None. K.M. Richardson: None. K. Spencer: None. N. Bennion: None. H. El Aldo Mikdachi: None. W.P. Irvin: None. C. Kersh: None.
2743 Radiation Dosimetry of Pelvic Floor and Non-Reproductive Sexual Organs in External Beam Radiation Therapy for Gynecologic Cancers J. Zhou, J. Prisciandaro, K. Maturen, C. Lockhart, L. Young, J. Balter, and S. Jolly; University of Michigan, Ann Arbor, MI Purpose/Objective(s): Sexual dysfunction and pelvic floor disorders are common in gynecologic cancer survivors. With the increasing use of MRI in radiation therapy (RT) treatment planning, small yet critical female
