ISSN 2347-3487 Volume 13 Number 5 Journal of Advances in Physics 4858 | Page May 2017 www.cirworld.com Study the Influence of Treatment Interruptions in the Radical Irradiation of Breast Cancer Ahmed H. Oraby 1 , Ibrahim A. Awad 2 , Ehab M. Attalla 3 , and Alia A. Azzam 4 1 Department of Physics, Faculty of Science, Mansoura University, Mansoura, Egypt 2 Department of Clinical Oncology and Nuclear Medicine, Faculty of Medicine, Mansoura University, Mansoura, Egypt awadonc@gmail.com 3 Department of Physics, Division of Medical Physics, National Cancer Institute, Cairo University & Children's Cancer Hospital, Cairo, Egypt attalla.ehab@gmail.com 4 Department of Clinical Oncology& Nuclear Medicine, Faculty of Medicine, Mansoura University, Mansoura, Egypt alia_a.azam@yahoo.com Abstract: Purpose: Hypofractionated radiotherapy (HFRT) in breast cancer treatment regimen (40 Grey /15 fractions/3 weeks) is more convenient for patients, especially those coming from remote areas to radiotherapy facilities and for healthcare providers, than conventional fractionation (50 Gy/25 fractions/5weeks). So the effect of radiotherapy interruption on treatment outcome (loco-regional control (LRC)& overall survival (OS)) during hypofractionated schedule is the issue of our study. Materials and Methods: We studied retrospectively 174 female patients with breast cancer who received PORT at the Clinical Oncology & Nuclear Medicine Department, Faculty of Medicine, Mansoura University, Egypt, from January-2012 to December-2016. We determined the treatment outcome (OS&LRC) from the follow-up (FU) of the studied patients, as the patient still survived or died, and recurrence till now occurred or not, and were estimated with the Kaplan-Meier (K- M) method and Logrank test, respectively. Then we calculated surviving fraction (SF) and tumor control probability (TCP) with regard to biologically effective dose (BED), for all patients, using breast cancer radiobiological parameters. Results: When comparing patients without radiotherapy gap with patients with radiotherapy gaps, the results showed a decrease in LRC rate in patients with radiotherapy treatment interruptions by 15 % (P=0.019, a significant value), but no detrimental effect on OS because of the very limited number of the studied patients. Curves of the relationship between (SF&OTT) and (TCP&OTT) confirmed the detrimental effect of unscheduled gap during radiotherapy fractions on the treatment outcome. Also we found a significant-P value for (marital status, start day of radiotherapy fractions, time, number, and duration of gaps); it means these factors affect LRC during radiotherapy interruptions. Conclusion: Interruptions during postoperative hypofractionated irradiation of breast cancer (40 Gy/15 fractions/3weeks) should be avoided and if they are inevitable, they should not be prolonged more than two days, as they will adversely affect the treatment outcome (LRC). Keywords: PORT: Post-Operative Radiotherapy, OTT: Overall Treatment Time, LR: Local Recurrence, HFRT: Hypofractionated radiotherapy, LRC: Loco-Regional Control, OS: Overall Survival, FU: Follow-Up, K-M: Kaplan-Meier, SF: Surviving Fraction, TCP: Tumor Control Probability, BED: Biologically Effective Dose, BCS: Breast Conserving Surgery, NACT: Neoadjuvant Chemotherapy, and PMRT: Postmastectomy Radiotherapy.] 1.INTRODUCTION Worldwide, breast cancer is the most common cancer among females [1]. Treatment of breast cancer includes surgical intervention, radiotherapy (RT), and systemic treatment with cytotoxic chemotherapy (CT), hormone therapy, targeted (biologic) therapy, or a combination of these [2, 3]. Radiation after breast conserving surgery (BCS) for early as well as locally advanced tumor after neoadjuvant chemotherapy (NACT) is now considered as an integral part of Breast Conserving Therapy (BCT) whereas postmastectomy radiotherapy (PMRT) to chest wall and or regional area is considered beneficial for a selected group of high risk patients [4-9]. PMRT decreases loco-regional recurrence (LRR) in women with operable breast cancer and inhances survival [10]. Conventional fractionated radiotherapy has been limit ed by patient’s compliance, travelling, unplanned interruption and others. Hypofractionated schedule would be more appealing and convenient [10]. In the clinical practice, daily, unplanned radiotherapy interruptions are inevitable because of intercurrent disease, acute radiation reactions, machine breakdowns, public holidays, and patient non-compliance [11]. Good clinical Practice (to achieve tumor control) dictates that radical courses of radiotherapy treatment should not be interrupted. Where this is not possible, compensatory treatment is required [12]. Recently it had been shown that radiotherapy interruptions lasting more than a week decreased LRC and OS (patient outcomes) rates in breast cancer patients treated with postoperative radiotherapy (PORT) after breast-conserving surgery brought to you by CORE View metadata, citation and similar papers at core.ac.uk provided by KHALSA PUBLICATIONS