The role of a prone setup in breast radiation therapy

Abstract

Most patients undergoing breast conservation therapy receive radiotherapy in the supine position. Historically, prone breast irradiation has been advocated for women with large pendulous breasts in order to decrease acute and late toxicities. With the advent of CT planning, the prone technique has become both feasible and reproducible. It was shown to be advantageous not only for women with larger breasts but in most patients since it consistently reduces, if not eliminates, the inclusion of heart and lung within the field. The prone setup has been accepted as the best localizing position for both MRI and stereotactic biopsy, but its adoption has been delayed in radiotherapy. New technological advances including image-modulated radiation therapy and image-guided radiation therapy have made possible the exploration of accelerated fractionation schemes with a concomitant boost to the tumor bed in the prone position, along with better imaging and verification of reproducibility of patient setup. This review describes some of the available techniques for prone breast radiotherapy and the available experience in their application. The NYU prone breast radiotherapy approach is discussed, including a summary of the results from several prospective trials.

Keywords: breast cancer; prone setup.

Figure 1

Prone breast positioning table Victoreen® Model 37-018. The table was designed based on MSKCC experience.

Figure 2

USC prone breast board for partial breast treatment. The contralateral opening is covered by the solid disk, the indexed breast is hanging through one of the rings inserted into the ipsilateral opening.

Figure 3

(A) NYU design, version 1. The board extends over the treatment couch, allowing couch rotation. By eliminating the ipsilateral bars tangential fields are possible. (B) NYU design, version 2. The board fully rests on the treatment couch. The leg support allowed a thinner board; therefore a soft cushion could be placed on the top, for patient comfort. Couch rotation is limited (<10°). (C) NYU design, version 3. Two-inch thick memory foam layer on top of 5 inch Styrofoam™, wrapped in washable vinyl cover. (For large breast carriers, additional Styrofoam™ layers can be used under the mattress).

Figure 4

(A) ClearVue™ System (Orbital Therapy): carbon fiber plate and board, soft cover for patient comfort. (B) The central segment can be rotated for right breast patients.

Figure 5

Access360™ (Varian Medical Systems): Built of carbon fiber mesh, with soft cushion on top. Attaches to the end of the treatment couch (replaces the upper section). An uncovered section of the mesh enables supraclavicular fields.

Figure 6

(A,B) Placement of the localization and setup BBs.

Figure 7

(A) Initial set up with the sternum lateral to the edge of the mattress and the contralateral breast creating a wedge at the midline. To avoid the contralateral breast the angle of the tangents would include part of the heart and LAD. (B) Once correctly aligned with the sternum more medial toward the edge of the mattress and the contralateral breast better displaced, the angle of the tangents permits exclusion of the contralateral breast, heart, and LAD, while including the entire parenchyma of the index breast (lateral edge is just anterior to the latissimus dorsi).