ESTRO 36 Abstract Book

S303 ESTRO 36 _______________________________________________________________________________________________

OC-0568 Accelerated PBI VS standard radiotherapy (IRMA trial): interim cosmetic and toxicity results B. Meduri 1 , A. Baldissera 2 , M. Galeandro 3 , E. Donini 2 , G. Tolento 4 , P. Giacobazzi 1 , T. Calmieri 3 , P. Vasilyeva 1 , A.G. Morganti 4 , S. Parisi 5 , S. Kaleci 6 , F. Lohr 1 , R. D'amico 6 , P.M. Poortmans 7 , F. Bertoni 1 , G.P. Frezza 2 1 Azienda Ospedaliero-Universitaria Policlinico di Modena, Radiotherapy Unit, Modena, Italy 2 Ospedale Bellaria – AUSL di Bologna, Radiotherapy Unit, Bologna, Italy 3 Arcispedale S..Maria Nuova – Azienda Ospedaliera di Reggio Emilia, Radiotherapy Unit, Reggio Emilia, Italy 4 University of Bologna, Radiation Oncology Center- Department of Experimental- Diagnostic and Specialty Medicine - DIMES, Bologna, Italy 5 Casa del sollievo della sofferenza – S. Giovanni Rotondo, Radiotherapy Unit, Foggia, Italy 6 Università di Modena e Reggio Emilia, Department of Medical Statistic, Modena, Italy 7 Radboud University Medical Center, Department of Radiation Oncology, The Netherlands, The Netherlands Purpose or Objective To report interim cosmetic and toxicity results in patients (pts) enrolled from 5 italian centers in the randomized IRMA trial. Material and Methods Women age ≥ 49 years with invasive breast cancer < 3 cm, pN0-1, were randomly assigned after breast-conserving surgery to 3D-CRT APBI (38.5 Gy in 10 fractions twice daily) or WBI (50 Gy in 25 daily fractions ± boost). Pts received adjuvant systemic therapy according to institutional guidelines. Cosmesis was assessed according to IRMA protocol parameters. Toxicity was scored according to RTOG tables. Results From March 2007 to December 2013, 983 pts were enrolled in IRMA from 5 italian centers (425 Bologna Bellaria, 240 Modena, 163 Reggio Emilia, 101 Bologna S.Orsola, 54 S.Giovanni Rotondo). Median follow-up was 5 years. No difference was observed in adverse cosmesis (fair and poor) among pts treated with APBI compared with WBI as assessed by physicians (20% vs 21.8% 1 year, 20% vs 19% 3 years) and by patients (14% vs 16% 1 years, 14% vs 14% 3 years). G3 acute skin toxicity was rare in both treatment arms (0% PBI vs 1.4% WBI), no further G3-4 acute toxicities were observed. G3-4 late skin toxicity was 0.42% (APBI) vs 0.79% (WBI) (p=0.4); G3-4 late subcutaneous tissue toxicity was 1.5% (APBI) vs 1.2% (WBI) (p=0.7); 2 rib fractures were observed in PBI patients; no further G3-4 late toxicities were observed. Axillary dissection (vs sentinel node) correlated with G3-4 late subcutaneous tissue toxicity (3.7% vs 0.9%, p<0.01); no correlation of toxicity with adjuvant chemotherapy was observed. Conclusion APBI with 3D-CRT resulted in similar acute and late toxicity and good/excellent cosmetic results compared with standard WBI. Additional follow-up is needed to confirm these results. OC-0569 Comparison of clinical outcome of APBI by interstitial brachytherapy as per ESTRO &ASTRO guidelines T. Telkhade 1 , T. Wadasadawala 1 , R. Upereti 2 , R. Sarin 1 , R. Jalali 1 , R. Badwe 3 , V. Parmar 3 , S. Gupta 4 , A. Budrukkar 1 1 Tata Memorial Hospital, Radiation oncology, Mumbai, India 2 Tata Memorial Hospital, Medical Physics, Mumbai, India 3 Tata Memorial Hospital, Surgical oncology, Mumbai, India 4 Tata Memorial Hospital, Medical oncology, Mumbai, India Purpose or Objective Lack of consistency in recommendations given by ASTRO and ESTRO for accelerated partial breast irradiation (APBI)

technique, showed an equivalent 1.5% rate of LR at a median 5-year follow-up time. Also age could play an important role in a multifactorial patient’s selection; the recently published subgroup analysis of the Florence trial concerning patients aged 70 years or older, showed an IBTR rate at 5 years of 1.9%, and significantly better results in terms of acute skin toxicity, in favor of APBI arm. Therefore, tumor biology seems to play a crucial role on patient’s selection; treatment decisions should always consider disease stage, comorbidities, and tumor biomarkers. Longer follow-up of recently presented studies with appropriately selected patients will be critical to define the rates of local control, survival, and long-term toxicity before APBI could be accepted as a standard alternative to conventional WBI. Outcome results from ongoing unpublished prospective trials (e. g. RAPID, IRMA, SHARE, NSABP B-39/RTOG 0413 trials) are awaited. SP-0567 Partial breast irradiation with brachytherapy: changing patient selection based on current evidence C. Polgár 1 1 National Institute of Oncology, Center of Radiotherapy, Budapest, Hungary In the last decades accelerated partial breast irradiation (APBI) has been intensively evaluated in prospective phase II and III clinical trials as a possible alternative to whole breast irradiation (WBI). Majority of these trials – using conservative patient selection criteria and proper treatment technique – were successful in yielding an annual local recurrence rate in the range of 0 to 1%. The 10-year results of the Hungarian phase III trial and more recently the 5-year results of the GEC-ESTRO phase III trial also demonstrated non-inferiority of APBI with intertitial brachytherapy compared to WBI. Despite variability in selection criteria, the majority of women treated within these trials were >40 years old, presented with node negative invasive ductal carcinomas up to 3 cm, without extensive intraductal component (EIC), and resected with clear margins. Based on available experience international guidelines have been published by the American Brachytherapy Society (ABS), the American Society for Therapeutic Radiology and Oncology (ASTRO), and the GEC-ESTRO (Table 1.) Table 1. International guidelines for APBI patient selection Criterion ABS ASTRO ESTRO Age (years) ≥ 50 > 50 > 50 Tumor size (cm) ≤ 3 ≤ 2 (DCIS ≤ 3) ≤ 3 Nodal status pN0 pN0 DCIS: ductal carcinoma in situ; IDC: invasive ductal carcinoma; ILC: invasive lobular carcinoma; ER: estrogen receptor; LVI: lymphovascular invasion. However controversy exists regarding the possible extension of selection criteria including patients younger than 50 years, women with invasive lobular carcinomas or DCIS, or patients with clear but close (< 2 mm) surgical margins. Ongoing clinical research actually focuses on better definition of candidates for APBI. As data from ongoing phase III trials mature, guidelines for patient selection should be revised and might be extended. However until additional long-term outcome reports of phase III trials are available, conservative patient selection criteria (as defined by the GEC-ESTRO and ASTRO) should be considered for selecting candidates for APBI. pN0 Histology All ivasive subtypes and DCIS Invasive ca. (excl. ILC) or low-risk DCIS Invasive ca. (excl. ILC) Margin status Negative Clear margin ≥ 2 mm Clear margin ≥ 2 mm ER status Any Positive Any LVI Not allowed Not allowed Not allowed