Fig 4.

Left ventricular (LV) segment injury by type of surgery and radiotherapy technique. Average typical doses to ventricular segments in radiotherapy for left-sided and right-sided breast cancer and numbers of women with ventricular injury in left-sided and right-sided breast cancer are shown. In each panel, segments are listed in order of difference in the average of the typical segment doses received in left-sided and right-sided breast cancer for women with injury to the segment concerned (ie, left-minus-right difference). Some women had injury to more than one segment. (*) Radiotherapy after breast-conserving surgery (BCS) included tangential radiotherapy in 90 of 99 women and anterior electron or orthovoltage radiotherapy in nine of 99 women. (†) Tangents delivered after BCS involved smaller left-minus-right dose differences to most LV segments than tangents after mastectomy because the fields were not as wide, with the medial border typically midline rather than contralateral. (‡) Techniques included tangential in 76 of 315 women, anterior electron or orthovoltage in 136 of 315 women, cobalt chain in 66 of 315 women, and anterior megavoltage in 37 of 315 women. Mean times to cardiac events were as follows: (A) radiotherapy after BCS left, 7.6 years; radiotherapy after BCS right, 9.6 years; (B) tangential radiotherapy after BCS left, 7.5 years; tangential radiotherapy after BCS right, 9.7 years; (C) radiotherapy after mastectomy left, 15.6 years; and radiotherapy after mastectomy right, 16.0 years.