ESTRO 36 Abstract Book

S632 ESTRO 36 _______________________________________________________________________________________________

EP-1163 A Prospective Evaluation of Lumpectomy Cavity Volume Changes During Whole Breast Radiotherapy B. Barney 1 , G. Martinez 1 , R. Hecox 1 , J. Clark 1 1 Intermountain Health Care, Radiation Oncology, Provo, USA Purpose or Objective A significant percentage of female post-lumpectomy breast cancer patients treated with whole breast radiotherapy (WBRT) have a lumpectomy cavity seroma on the initial CT simulation. Our purpose was to prospectively evaluate for changes in the size of the postoperative tumor bed during a course of WBRT, prior to the lumpectomy cavity boost (LCB). Material and Methods This prospective study was approved by the IRB, and informed consent was given by 20 women prior to study enrollment. All patients underwent breast conserving surgery and received a recommendation for LCB following WBRT by the treating physician. The median patient age was 63 years (range, 41-84). Most patients (n=19, 95%) had Stage 0, I, or II breast cancer. There was no standardized dose or fractionation for WBRT or the boost; these decisions were left to the treating physician’s discretion. Regional lymph nodes were treated as per standardized guidelines. When chemotherapy was required, it preceded WBRT. Each patient underwent initial CT simulation (CT1) at a median 39 days (range, 11-216) from surgery. Twelve women (60%) had a lumpectomy cavity seroma on CT1, and 8 (40%) did not. All patients underwent a second CT simulation (CT2) approximately 1 week before the LCB began. Median time from CT1 and CT2 was 30 days (range, 21-42). The LCB volume was immediately contoured on CT1 based on surgical clips, presence/location of seroma, and surgical findings. Without referencing CT1 LCB contours, the treating physician then contoured a modified LCB volume once CT2 was obtained, using the same factors for CT1 LCB delineation. We prospectively compared LCB volumes from CT1 and CT2 across the cohort and within seroma/no seroma subgroups. Univariate analysis of several factors potentially associated with a change in LCB volume from CT1 to CT2, including time from surgery to CT1 (≤40 days vs >40 days), time from CT1 to CT2 (≤30 days vs >30 days), and presence of seroma on CT1, was performed. Results The median LCB volumes on CT1 and CT2 for the entire cohort were 20.1 and 8.5 cm 3 , respectively. Most patients (n=17, 85%) experienced a reduction (rather than increase) in the LCB volume from CT1 to CT2. For patients with seromas, median LCB volumes on CT1 and CT2 were 36.0 and 8.8cm 3 , respectively, representing a volume reduction of >75% over the course of WBRT. For patients without seromas, median LCB volumes on CT1 and CT2 were 11.8 and 8.0cm 3 , respectively, representing a volume reduction of 32% during WBRT. On univariate analysis, only the presence of seroma was associated with a significant change in LCB volume during WBRT. Conclusion Most patients experienced a change in the size of the LCB volume during WBRT. Patients with seroma experienced a more dramatic volume reduction than those without. We recommend that women who will undergo LCB and have a seroma at the time of initial CT simulation undergo a re-simulation to plan the LCB boost towards the end of the WBRT course.

No pulmonary or cardiac toxicity was observed. Although the series is not homogeneus, there was no significant difference in the incidence of acute or late toxicity in pts that underwent or not to chemotherapy. Conclusion In our seriesHRT is well tollerated with a good toxicity profile and a good cosmetic result. There is no clear evidence that chemotherapy has an impact to acute or late skin toxicity after HRT. In our analysis we can not evaluate the role that have sequential boost in causing late toxicity. EP-1162 Non surgical breast conserving treatment using a new radiosensitizer T. Shimbo 1 , K. Yoshida 1 , N. Yoshikawa 1 , H. Yoshioka 1 , M. Nakata 1 , Y. Narumi 1 , T. Komori 1 , H. Matsutani 1 , T. Hamada 1 , Y. Uesugi 2 1 Osaka Medical College, Radiation Oncology, Osaka, Japan 2 Kansai University of Welfare Sciences, Medical treatment for health, Kashihara, Japan Purpose or Objective The purpose of this clinical study was to clarify a non- surgical breast-conserving therapy (BCT) using a new radiosensitizing agent for the early stage breast cancer patients who rejected surgery. This new radiosensitizer, named KORTUC (Kochi Oxydol-Radiation Therapy for Unresectabe Carcinomas) containing 0.5% hydrogen peroxide and 0.83% sodium hyaluronate has been developed for intra-tumoral injection in various tumors. Hydrogen peroxide is the only agent known to be capable of inactivating antioxidative enzymes and producing oxygen when applied topically to tumor tissues. By the addition of sodium hyaluronate, which makes the solution more viscous and slows the degradation of hydrogen peroxide, allowing long-acting radiosensitization of the local tumor tissue. Material and Methods A total of five early stage breast cancer patients (stage I, 2; stage II, 3) who rejected surgery were enrolled in the KORTUC trial after providing a fully informed consent. The mean age of the patients was 67.5 years (range; 38- 80). The tumor size was 24.6mm (range; 14-47). A maximum of 6 mL of the radiosensitizar agent was injected into breast tumor tissue twice a week under ultrasonographic guidance. We used hypo-fractionated radiotherapy with conventional linear accelerator. Forty- four Gy in 16 fractions were irradiated for whole breast and ipsilateral axillary region with tangential field, and an additional electron boost of 9Gy in 3fractions were delivered for primary tumor site. Results Treatment was well tolerated with minimal adverse effects in all patients. No patients showed any significant complications other than mild dermatitis. Three patients with estrogen receptor-positive tumors were also started on hormone therapy following KORTUC treatment. All patients showed clinically complete response (cCR). The mean duration of a follow-up was 15.6 months (5/23/26/27/44 months), respectively. All patients were alive with no evidence of disease at present. The mean period taken to confirm cCR on the breast contrast- enhanced CT, MRI or PET-CT was approximately 8.2 months. Cosmetically, all patients evaluated as having an excellent appearance in their ipsilateral breast. Conclusion Non-surgical BCT (KORTUC-BCT) can be performed safely and effectively for patients with early stage breast cancer. KORTUC-BCT can be one of the treatment options to breast cancer patients who rejected surgery.