Comparing different techniques of Post Axillary field in Breast Cancer Treatment

Abstract

As we know breast cancer is the second death reason in Iran. One step of treatment process is radiotherapy, which needs careful consideration of contouring and therapeutic techniques Lung, thyroid, spinal cord, trachea and humerus are sensitive organs in breast cancer radiation therapy. The most clinical studies recommended two ways for delivering 95 percent of dose to supraclavicular and axillary nodes, one of them is an anterior field with a posterior axillary boost (AP-PAB) technique for the axillary lymph nodes and supraclavicular treatment and another one is an anterior to posterior parallel pair (AP-PA) technique, at Reza Radiotherapy and Oncology Center in Mashhad an anterior to posterior parallel pair (AP-PA) technique was used. The aim of this study is comparing and evaluating delivered dose for all organs in these techniques. The study population comprised breast cancer patient in Reza Radiation and Oncology Center (2016). Prowess panther version 5.2 was used as a treatment planning software. Plans for 20 breast cancer cases were done with (AP-PAB) technique and (AP-PA) technique. In each techniques delivered dose was investigated for lung, spinal cord, humerus, thyroid, trachea, supraclavicular lymph node, axillary lymph node and the hot spot. Organ at risk and nodes delivered dose were compared. By comparing two technique dose volume histogram for each breast cancer case, based on the analysis of data collected by software SPSS (p value=0.7 for average dose at 30% of lung volume, p value=0.2 for average dose at 95% of axillary lymph nodes volume, p value=0.8 for average dose at thyroid, p value=0.8 for average dose at humerus, p value=0.6 for average dose at trachea, p value=0.5 for average of maximum dose at spinal cord and p value=0.08 for average dose at 95% of supraclavicular lymph nodes volume. According to the results there is not significant difference between these techniques because p value is higher than 0.05 for all organs in the other hand average dose at 30% of lung volume is 2% lower in (AP- PAB) technique, average dose at thyroid is 1% lower in (AP-PAB) technique, average dose at trachea is 4% lower and average of maximum dose at spinal cord is 4% lower in (AP-PAB) technique. Average dose at 95% of axillary lymph nodes volume is 0.9% higher in (AP-PAB) technique also average dose at 95% of supraclavicular lymph nodes volume is 1.2% higher and average dose at humerus is 1.7% lower in (AP-PA) technique. This study shows (AP- PAB) technique is acceptable for patients with critical conditions (cases with high dose constrain of organ at risk.