Abstracts of Scientific Presentations at the 18th Annual Meeting of the American College of Radiation Oncologys of Scientific Presentations at the 18th Annual Meeting of the American College of Radiation Oncology 003 Assessment of Radiation-Induced Fibrosis (RIF) of Breast Tissue with TCM and Radiologic Imaging: Preliminary Results Preeti Parhar, Lea Baer, Margarita Rasca, Linda Moy, and Gabriella Wernicke, NYU. Background: While clinical palpation of RIF is subjective due to high inter-observer variability, tissue compliance meter (TCM) has emerged as a new non-invasive and more objective modality. Hypo-fractionated adjuvant radiotherapy (HFRT) to the breast predisposes to developing higher degree RIF than conventional radiation (RT). We compared RIF assessment by palpation and TCM to the findings of routine follow-up imaging in patients treated with adjuvant HFRT for breast cancer. Methods: Women were treated with HFRT with doses to the tumor bed of 30Gy (6Gy/fraction) and 48Gy (3.2Gy/fraction) in 14/17 and 3/17 women, respectively. RIF was evaluated by palpation and TCM by 2 blinded radiation oncologists. By palpation, grades 1, 2, and 3 corresponded to mild, moderate, and severe RIF, respectively. TCM measured degree of compliance (DC) of RIF in irradiated breast (RTB) and DC in the corresponding area of the non-irradiated breast (NRTB). Architectural distortions (AD) with RIF (ADRIF) on the most recent mammogram, US, and MRI were assessed by a radiologist blinded to both the TCM and palpation findings. Kinetic analysis (KA) on MRI was performed using the DynaCAD (Invivo, Milwaukee) device. Results: All 17 women were evaluated. The median time of follow up from completion of RT is 3.9 years (range, 1.1–6.5 years). RIF by palpation revealed grades 1, 2, and 3 in 4, 10, and 3 patients, respectively. TCM rendered an average difference in DC in RTB versus NRTB of 18%, 37%, and 50% for grades 1, 2, and 3 RIF, respectively. Average size (AS) of ADRIF was estimated by mammograms, US, and MRI as 6.1 cm (range, 3.4 – 9.8 cm), 4.1 cm (range, 2.6–6.8 cm), and 14.3 cc (range, 8–24 cc), respectively. There was no correlation between AS of the ADRIF measured by these imaging modalities and RIF assessed by palpation or TCM. Further, RIF could not be assessed separately from ADRIF. Grades 2–3 RIF and DC 37% corresponded to a higher rate of contrast wash-out (23%) by KA, as compared to grade 1 RIF and DC 37% and lower rate of wash-out (9%). Conclusions: Our preliminary data suggest that TCM findings correlated better to palpation than any imaging study in evaluating RIF. KA of MRI may also be helpful, but additional patients are needed to confirm our results. 005 Is Stereotactic Body Radiotherapy (SRBT) Safe for Central Nonsmall Cell Lung Cancer (NSCLC) Lesions? Anushka Patel, Munther Ajlouni, Jianyue Jin, Mei Lu, and Benjamin Movsas, Henry Ford Hospital. Purpose: Stereotactic body radiation therapy (SBRT) is an emerging treatment for peripherally located inoperable early stage or recurrent non-small cell lung cancer (NSCLC). Timmerman et al. reported a 1-yr grade 3–5 toxicity rate of 25% for central lesions treated to 60 Gy in 3 fractions. We report our experience evaluating toxicity and efficacy of SBRT for central lesions. Materials and Methods: Nine patients with / 4 cm pathologically documented central NSCLC lesions were studied. All patients underwent gated CT treatment planning. The Novalis system delivered the SBRT, which ranged from 36 Gy (with prior history of EBRT) to 48 Gy (no prior history of EBRT) delivered in 12 Gy fractions over two weeks. All patients had a follow-up CT of the thorax at 6 weeks and every 3 months. Acute and chronic toxicities were assessed. Results: The median follow-up was 14 months (8–21 months). The highest grade toxicity was grade 2 dyspnea in one patient with a history of COPD. Grade 1 toxicities (cough) were observed in 3 patients. Two patients had a complete response, four had a partial response, and one lesion remained stable. Two patients receiving 36 Gy developed local progression. Using the Kaplan-Meir approach, the actuarial rate of local control at one year was 87% and the rate of freedom from grade 3–5 toxicity was 100%. Discussion: The toxicity profile for centrally located NSCLC lesions treated with SBRT (to 36–48 Gy in 3–4 fractions) is very low with a promising local control at one year of 87%. 007 Seroma Formation During Mammosite Brachytherapy Can Influence Prescribed Treatment Doses Albert DeNittis, Jessica Katz, Andrew Anderson, Ned Carp, Paul Gilman, and Weiss Marisa, Lankenau Hospital. Purpose: To demonstrate that progressive seroma formation can impact and deviate dose delivered to a part of the tumor bed during accelerated partial breast irradiation with a Mammosite catheter. Methodology: One hundred-two patients have been treated at our institution using the Mammosite balloon. We perform daily pretreatment quality assurance using computed tomography for balloon dimensional analysis. Balloon integrity, position and size are assessed. During treatment one patient developed progressive seroma, which in retrospect, had influenced and changed the prescribed dose delivered to the target tissues at risk. Results: One patient had developed a progressive eccentric seroma during treatment. The tissue surrounding the seroma received less than the prescribed dose. Serial daily CT scans had showed that tissues at the one cm depth adjacent to the seroma had received 100% (340 cGy) on day 1, 59% (200 cGy) on day 2, 29% (100 cGy) on day 3, 12% (40 cGy) on day 4, and 10% (35 cGy) on day 5. Conclusions: Seroma formation during treatment occurs infrequently. Treating physicians should be aware of potential problems with associated underdosing of the breast tumor bed surrounding the seroma. Seroma drainage during treatment should be considered. 008 A Systematic Review and Meta-Analysis of Randomized Trials Assessing the Impact of Axillary Lymph Node Dissection on Breast Cancer Outcome in Clinically Node Negative Patients Mona Sanghani,* Ethan Balk,* and Blake Cady,† *Tufts-New England Medical Center; †Rhode Island Hospital. Introduction: The regional lymph node control and survival impact of axillary nodal dissection (dxn) in patients with breast cancer has been the subject of multiple randomized trials, with varying results. The aim of this study was to review and conduct a meta-analysis of contemporary trials of American Journal of Clinical Oncology • Volume 31, Number 6, December 2008 606 axillary dxn in patients with early stage breast cancer to assess whether a survival benefit exists with nodal dissection. Methods: A systematic MEDLINE review was conducted to identify randomized trials of axillary dxn versus no dxn in clinically node negative patients with early stage breast cancer published between January 2000 and January 2007. Three such studies were identified. A fourth trial of axillary radiotherapy versus no axillary treatment was also identified and included in this review. Meta-analyses were performed of overall survival, axillary nodal recurrence, metastatic disease, and ipsilateral breast cancer recurrence. Results: All four randomized trials reported a higher rate of axillary regional recurrence (1.5–3%, median follow-up 5–15 years) in the absence of axillary dxn or radiotherapy. Overall survival was similar with and without definitive axillary treatment in three out of the four reviewed trials at last update and was attributable to an increased rate of non-breast cancer death in the single trial showing a survival benefit to axillary treatment. Meta-analysis found no significant difference in overall survival (OR 1.55, 95% CI 0.74–3.24), disease-free survival (OR 1.08, 95% CI 0.82–1.42, P 0.61), metastatic disease (OR 0.91, 95% CI 0.65–1.29), or ipsilateral breast cancer recurrence (OR 1.11, 95% CI 0.68–1.83) associated with axillary treatment. A significantly lower rate of axillary recurrence was seen in patients who underwent lymphadenectomy (OR 0.28, 95% CI 0.11–0.73, P 0.01). Conclusions: Axillary lymph node dxn does not confer a survival benefit in the setting of early stage clinically node negative breast cancer. 009 Investigation of Implanted Prostate Marker Migration Using TomoTherapy Daily MVCT Images Baoqing Li, Chuan Wu, James Purdy, and Srinivasan Vijayakumar, University of California Davis Cancer Center. Purpose: The aim of this study was to assess the significance of daily inter-fraction migration of gold fiducial markers within the prostate using pre-treatment MVCT images acquired on a TomoTherapy unit, in contrast to results from previous studies that were based on only periodic “snapshots” of electronic portal imaging or films rather than daily volumetric CT images. Methods and Materials: Three gold markers were implanted in the prostate of low or intermediate risk prostate cancer patients, who subsequently received radiation to a total dose of 72 Gy with 2 Gy per fraction on TomoTherapy. For each patient, a daily MV CT was acquired. The 3D coordinates of each marker were manually recorded from MV CT images. The daily inter-marker distances were calculated to evaluate the interfraction marker migration. The data from five patients randomly selected were used in this analysis. Results: The standard deviation (SD) of inter-marker distance is small, (SD ranges from 1.1 mm to 2.0 mm and the average of SD 1.5 mm), which is consistent with the results from previous studies using portal imaging or verification films techniques. Inter-marker distances as a function of fraction index are shown for each patient. The mean of each inter-marker distances for the last 5 fractions is compared with that for the first 5 fractions. The differences ranges from 0.1 mm to 3.4 mm, and the average is 1.9 mm, indicating a time trend of noticeable shrinkage of the prostate gland. Conclusions: The study confirms that the standard deviation of inter-marker distance is small