Prone accelerated partial breast irradiation (five fractions) after breast conservation therapy with heart and lung sparing. S. C. Formenti, J. Goldberg, B. Rosenstein, K. Dewyngaert; New York University, New York, NY Abstract: Background: The convenience of a shorter course of adjuvant radiation after breast conservation therapy (BCT) has encouraged the exploration of partial breast radiation techniques. We are reporting the clinical and physical results of the first 47 patients accrued to an ongoing accelerated partial breast irradiation (APBI) protocol utilizing three dimensional conformal radiation therapy (3D-CRT) in prone position after BCT ( supported by DOD DAMD 17-01-1-0345). Methods: A regimen of external beam conformal hypo-fractionated radiotherapy directed to the original tumor bed with margins was prospectively tested in a phase I/II study. Post-menopausal women with non-palpable T1N0 breast cancer, excised with at least 5 mm margins, lack of EIC, and receptor positive tumors were offered eligibility to the study only if they had first refused six weeks of standard radiation. Planning CT and treatment were performed in the prone position, on a dedicated table to best spare heart and lung tissues. The planning target volume (PTV) was defined at CT as the post-excisoinal surgical cavity plus a 2 cm margin(Varian Somavision/CadPlan/Eclipse). Based on radiobiological modeling, the prescribed dose (PD) was 6 Gy per fraction delivered to the 95% isodose surface in 5 fractions over ten days to a total dose of 30 Gy. A 2-stage Simon design with projected enrollment of at most 99 patients was used (significance level of 0.05 and power of 0.80). Results: 47 patients have completed treatment. Median age is 67.5 years (51 - 85) and median tumor diameter is 1 cm (0.2-1.9). Acute effects were limited to Grade 1-2 erythema in 22/47 patients (47%). The mean volume of the ipsilateral breast (IBV) receiving 100% of the PD was 26% (range 10-45%). The mean volume receiving 50% of the PD was 47% (range 23-75%). In all patients no significant heart or lung volume was treated by the prone technique. At a median follow-up of 2 years, no patient has recurred. Conclusions: These preliminary data support the feasibility of prone APBI, which is well tolerated and enables heart and lung sparing. Longer follow-up is required to assess efficacy and long term cosmetic results. Abstract No: 870 Remember we are NOT Doctors and have NO medical training. This site is like an Encylopedia - there are many pages, many links on many topics. Support our work with any size DONATION - see left side of any page - for how to donate. You can help raise awareness of CAM.