Three-dimensional conformal breast irradiation in the prone position

Abstract

The prone position can be used for the planning of adjuvant radiotherapy after conservative breast surgery in order to deliver less irradiation to lung and cardiac tissue. In the present study, we compared the results of three-dimensional conformal radiotherapy planning for five patients irradiated in the supine and prone position. Tumor stage was T1N0M0 in four patients and T1N1M0 in one. All patients had been previously submitted to conservative breast surgery. Breast size was large in three patients and moderate in the other two. Irradiation in the prone position was performed using an immobilization foam pad with a hole cut into it to accommodate the breast so that it would hang down away from the chest wall. Dose-volume histograms showed that mean irradiation doses reaching the ipsilateral lung were 8.3 ± 3.6 Gy with the patient in the supine position and 1.4 ± 1.0 Gy with the patient in the prone position (P = 0.043). The values for the contralateral lung were 1.3 ± 0.7 and 0.3 ± 0.1 Gy (P = 0.043) and the values for cardiac tissue were 4.6 ± 1.6 and 3.0 ± 1.7 Gy (P = 0.079), respectively. Thus, the dose-volume histograms demonstrated that lung tissue irradiation was significantly lower with the patient in the prone position than in the supine position. Large-breasted women appeared to benefit most from irradiation in the prone position. Prone position breast irradiation appears to be a simple and effective alternative to the conventional supine position for patients with large breasts, since they are subjected to lower pulmonary doses which may cause less pulmonary side effects in the future.

Individual Positioning: A Comparative Study of Adjuvant Breast Radiotherapy in the Prone Versus Supine Position

“…Some studies suggest a reduction in heart doses as a result of prone positioning but do not provide direct comparisons with supine positioning (5,8). Others are consistent with our results in showing no significant difference in doses to the heart as a function of the treatment position (6,7,9). This finding may be accepted if the change in position of the heart by treatment position is taken into consideration.…”

“…Some focused on dose distribution (6,7,9,18) and others on clinical implementation (11,12,14,19,20); only one study with both dosimetric aspects and feasibility (10). This study is the first randomized clinical trial to compare breast radiotherapy in the prone vs. the supine position.…”

“…The simplest way to protect the OARs during breast radiotherapy is individual patient positioning. It has been observed that a prone position during breast radiotherapy results in a substantially lower dose to OARs such as the ipsilateral lung (5)(6)(7)(8)(9) and the heart (5,8), with the additional advantage of improved dose homogeneity (5,6,9). This mode of positioning has been shown to be feasible (10,11), even in obese patients (8), and to provide a similar long-term outcome and toxicity as with standard supine tangents (11,12).…”

New possibilities for the tailored therapy of breast cancer patients

“…Others are consistent with our results in showing no significant difference in the doses to the heart as a function of the treatment position (52)(53)(54). This finding may be accepted if the change in position of the heart by treatment position is taken into consideration.…”

“…All authors agree that the lung doses are dramatically reduced if breast radiotherapy is performed with the patient prone (52)(53)(54)65,66). The beneficial effect of prone positioning on the protection of the ipsilateral lung is further enhanced if the almost absent intrafractional motion of the chest wall is taken into account for the calculation of safety margins around the CTV (60,67,68).…”