Whole breast radiotherapy in prone and supine position: is there a place for multi-beam IMRT?

Abstract

BackgroundEarly stage breast cancer patients are long-term survivors and finding techniques that may lower acute and late radiotherapy-induced toxicity is crucial. We compared dosimetry of wedged tangential fields (W-TF), tangential field intensity-modulated radiotherapy (TF-IMRT) and multi-beam IMRT (MB-IMRT) in prone and supine positions for whole-breast irradiation (WBI).MethodsMB-IMRT, TF-IMRT and W-TF treatment plans in prone and supine positions were generated for 18 unselected breast cancer patients. The median prescription dose to the optimized planning target volume (PTVoptim) was 50 Gy in 25 fractions. Dose-volume parameters and indices of conformity were calculated for the PTVoptim and organs-at-risk.ResultsProne MB-IMRT achieved (p<0.01) the best dose homogeneity compared to WTF in the prone position and WTF and MB-IMRT in the supine position. Prone IMRT scored better for all dose indices. MB-IMRT lowered lung and heart dose (p<0.05) in supine position, however the lowest ipsilateral lung doses (p<0.001) were in prone position. In left-sided breast cancer patients population averages for heart sparing by radiation dose was better in prone position; though non-significant. For patients with a PTVoptim volume ≥600 cc heart dose was consistently lower in prone position; while for patients with smaller breasts heart dose metrics were comparable or worse compared to supine MB-IMRT. Doses to the contralateral breast were similar regardless of position or technique. Dosimetry of prone MB-IMRT and prone TF-IMRT differed slightly.ConclusionsMB-IMRT is the treatment of choice in supine position. Prone IMRT is superior to any supine treatment for right-sided breast cancer patients and left-sided breast cancer patients with larger breasts by obtaining better conformity indices, target dose distribution and sparing of the organs-at-risk. The influence of treatment techniques in prone position is less pronounced; moreover dosimetric differences between TF-IMRT and MB-IMRT are rather small.

Does an integrated boost increase acute toxicity in prone hypofractionated breast irradiation? A randomized controlled trial

“…For the supine cohort of this study, a multibeam IMRT technique was used, which is not commonly used for WBI. We chose this technique to compare prone IMRT with the best supine technique at our center (17). If we compare our results with the 2-year results of the Cambridge IMRT trial (26), less edema, retraction, and fibrosis and fewer telangiectasias were observed in our supine cohort.…”

“…A 2-beam tangential field IMRT technique was used in the prone position and a 6-beam IMRT technique in the supine position. Both techniques have been described elsewhere (17). In almost all patients, a multibeam IMRT technique was used for boost irradiation.…”

Feasibility evaluation of prone breast irradiation with the Sagittilt© system including residual-intrafractional error assessment

“…Moreover, they concluded that if simultaneous integrated boost is not planned, 3D conformal radiotherapy can be an adequate approach for prone whole-breast irradiation. Similarly, Mulliez et al found only rather small dosimetric differences between tangential-field and multibeam IMRT in prone position [9].…”

“…One promising all-in-one solution could be the prone position. Prone position significantly reduces respiratory motions, lung doses and acute radiotherapy side effects as compared to supine position [5,9,[14][15][16][17][18]. Prone position has already been shown to be superior for heart-sparing mainly in patients with large breast volumes [5,18,19].…”

“…Concerning large breast volumes, some efforts should be made to reduce the dose to the organs at risk [2][3][4] and to avoid hot spots within the target to prevent cardiac failure, secondary lung cancer, acute toxicity and impaired cosmetics [5][6][7]. To achieve these requirements various solutions exist, including the use of advanced radiotherapy techniques with or without deep inspiration breath-hold [8][9][10] or changing treatment position [5,11] or both [9,12,13]. One promising all-in-one solution could be the prone position.…”