Purpose: The aim of this study was to investigate the gantry angle dependency of the multileaf collimator (MLC) leaf position error. Methods: An automatic MLC quality assurance system (AutoMLCQA) was developed to evaluate the gantry angle dependency of the MLC leaf position error using an electronic portal imaging device (EPID). To eliminate the EPID position error due to gantry rotation, we designed a reference maker (RM) that could be inserted into the wedge mount. After setting up the EPID, a reference image was taken of the RM using an open field. Next, an EPID‐based picket‐fence test (PFT) was performed without the RM. These procedures were repeated at every 45° intervals of the gantry angle. A total of eight reference images and PFT image sets were analyzed using in‐house software. The average MLC leaf position error was calculated at five pickets (‐10, ‐5, 0, 5, and 10 cm) in accordance with general PFT guidelines using in‐house software. This test was carried out for four linear accelerators. Results: The average MLC leaf position errors were within the set criterion of <1 mm (actual errors ranged from ‐0.7 to 0.8 mm) for all gantry angles, but significant gantry angle dependency was observed in all machines. The error was smaller at a gantry angle of 0° but increased toward the positive direction with gantry angle increments in the clockwise direction. The error reached a maximum value at a gantry angle of 90° and then gradually decreased until 180°. In the counter‐clockwise rotation of the gantry, the same pattern of error was observed but the error increased in the negative direction. Conclusion: The AutoMLCQA system was useful to evaluate the MLC leaf position error for various gantry angles without the EPID position error. The Gantry angle dependency should be considered during MLC leaf position error analysis.

Background: Inflammation is a key regulatory process in breast cancer progression and severity. Several studies have demonstrated that prolonged exposure of breast tumor cells to inflammatory cytokines leads to epithelial-mesenchymal transitions (EMT), which is the principle mechanism involved in metastasis and tumor invasion. Disruption of the signaling pathways involved in EMT may therefore provide an effective treatment strategy for currently difficult to treat or untreatable cancers such as TNBC. The interleukin (IL)-1 plays a pivotal role on breast cancer proliferation, invasion and/or inflammation. Here, we investigated the correlation of MMP-3 and IL-8 on IL-1b-induced cell migration and invasion as well as the inhibitory effect of zerumbone on IL-1β-induced MMP-3 and IL-8. Methods: Triple negative breast cancer cells (Hs578T and MDA-MB231) were cultured DMEM with 10% FBS and 1% antibiotics. The levels of IL-8 and MMP-3 mRNA were analyzed by real-time PCR. The levels of secreted IL-8 and MMP-3 protein expression were analyzed by ELISA and western blot analysis, respectively. Cell viabilities by drug were analyzed by MTT assay. Cell invasion and migration was detected by Boyden chamber assay. Results: The level of IL-8 and MMP-3 mRNA and protein expression significantly increased by IL-1β treatment in both Hs578T cells and MDA-MB231 cells. In addition, IL-1β-induced cell migration and invasion also increased in Hs578T and MDA-MB231 cells. On the other hand, the levels of basal and IL-1β-induced IL-8 and MMP-3 expression were decreased by zerumbone. Conclusion: IL-1β induces the migration and invasion of breast cancer cells through IL-8 and MMP-3 expression. These effects are significantly suppressed by zerumbone. Therefore, we suggest that zerumbone may act as a useful therapeutic agent for treatment of triple negative breast cancer. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P2-09-19.

Background: Endocrine therapy has dramatic improvements of prognosis in patients with hormonal receptor positive breast cancer. However, long-term follow up shows that endocrine resistance is still major clinical concern. Although the value of estrogen receptor (ER) level can predict response to endocrine treatment in hormonal receptor positive breast cancers, few markers are available that can predict response to endocrine treatment. We attempted to identify molecular markers, especially progesterone receptor (PR), associated with endocrine failure in breast cancer. Methods: We reviewed the medical records of 2513 breast cancer patients who underwent breast surgery and endocrine therapy at Samsung Medical Center between March 2007 and July 2011. Patients were compared according to ER and PR expression and to assess the clinical and biological features of ER+positive/PR-negative breast cancers to understand how PR might be a useful marker of these activities. ER and PR expression accessed using Allred score, the ‘positive” was defined that total score is larger than 2. Results PR negative tumors were found more frequently in postmenopausal women (post- 11.2% vs. pre- 2.5%, P &lt; 0.001) and PR negative tumors were significantly associated with higher grade, higher level of Ki 67 and more expression of EGFR and CK5/6. In Kaplan-Meier analysis and multivariate analysis, PR negativity was significantly poorer prognostic factor of DFS (HR 3.1, 95% CI 1.2-8.2, P = 0.021) and OS (HR 89.8, 95% CI 3.4-2352.3, P = 0.007). Stratified by the menopausal status, there was not shown significant difference of survival between the PR+ and PR- tumor in postmenopausal women (DFS, HR 2.1, 95% CI 0.4-10.8, P = 0.381; OS, HR 10.6, 95% CI 0.6-171.4, P = 0.096). However, PR negative tumors showed an association with poor outcome in premenopausal women (DFS, HR 7.2, 95% CI 2.5-20.6, P &lt;0.001; OS, HR 24.6, 95% CI 2.2-275.6, P = 0.009). Conclusion: In HR positive breast cancers, PR negative tumors were found more frequently in elderly, postmenopausal women. However, PR negative tumors are shown more aggressive and poorer survival than PR positive tumors despite of endocrine therapy, especially in premenopausal women. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P5-09-17.