Do conventional radiotherapy fields irradiate the regional lymphatics correctly in patients with breast cancer?.
Bildiriler > Özet Bildiri
Yazarlar: A Haydaroglu, O Karakoyun-Celik, Sinan HOCA, Y Bolukbasi, Nezahat OLACAK
Cancer Research, , , Uluslararası, Özet Bildiri, Wos, cilt 69, ss 5147-5147
DOI: 10.1158/0008-5472.sabcs-5147
Özet
Abstract Abstract #5147 Purpose: In this study, we compared the 3-Dimentional Conformal Radiotherapy (Method I) and conventional radiotherapy (Method II) plans of patients who receive loco-regional irradiation for breast cancer. Two methods were analyzed statistically with DVH's. Material and Methods: Twenty-five patients underwent computed tomography (CT) scanning in the supine treatment position and axial images with slice thickness of 5 mm were obtained. The patients were virtually treated and a total dose of 50 Gy with 2 Gy/fraction was prescribed to the PTV using 6 MV photon beams. In Method I, breast or chest wall volumes, axillary levels (AL) I, II and III and supraclavicular lymph node (SC) volumes delineated and then radiotherapy fields, tangents, SC and posterior axillary boost (PAB) were developed according to each patients own anatomy. The depth for SC lymph nodes was measured from the isocenter of SC field, for AL's II and III lymph nodes from the isocenter of PAB field in each patient. In Method II, conventional radiotherapy fields which include standard tangents, SC and PAB fields were developed on DRR images for each patient. Dose prescribed to a tissue depth of 3 cm for SC, to the midaxillary depth for PAB field. Analyses were done using composite plans of tangents, SC and PAB fields of each method. The volumes of AL's II and III out of PAB field were identified, and the dose distributions were assessed from the DVH's of the contoured volumes. Results: The mean depth of midaxillary level was 7.75 cm (6.5-8.5). In Method I, the maximum mean depths for AL II and III were 6.5 and 5.3 respectively; both two levels were anterior to the midaxillary level. The mean depth of SC lymph nodes was 4.6 cm (3.3-8.6) that is more that 3 cm. In Method II, the mean volume percentage received 50 Gy was lower than Method I. This was due to SC depth, majority of the patients had more that 3 cm SC depth. Mean 50 Gy volume was 98 % in Method I, where as 65% in Method II (p=0.00001). In Method II, a part of AL II lymph nodes were out of PAB field in 9 (36%) patients and a part of AL III lymph nodes were out of PAB field in 18 (72%) patients. Conclusion: Both SC and AL's II and III lymph node depths were presented a wide variety. Additionally, AL II and III lymph nodes were out of PAB fields in a significant number of patient's Method II plans. According to this study, the mean depth of SC lymph nodes was deeper than 3 cm and AL II and III lymph nodes were anterior to the midaxillary depth. For this reasons, SC lymph nodes received less than prescribed 50 Gy. Three-Dimensional Conformal Radiotherapy, delineating regional lymph nodes is more effective in achieving better dose and nodal volume coverage than that of the conventional radiotherapy in patients with breast cancer. Citation Information: Cancer Res 2009;69(2 Suppl):Abstract nr 5147.