Clips and scar as the guidelines for breast radiation boost after lumpectomy

Background and Aims: Breast-conserving therapy in early breast cancer is equally effective as mastectomy, with advantages of cosmesis and quality of life over mastectomy. Local control is improved when entire breast irradiation is combined with a radiation boost to the tumour bed. Methods: Localization of the tumour bed was compared in 45 consecutive patients using surgical scar and radiopaque clips placed intra-operatively in the lumpectomy cavity. Results: The area (A) of the radiation boost field and volume (V) of the tumour bed, designed on the basis of scar (AS and VS), were 1.4 times larger than those designed on the basis of the clips (AC and VC). AS and VS missed about one-quarter of the tumour bed which had been delineated by clips intra-operatively, while about one-half of it encompassed tissues beyond the AC and VC. Conclusions: A boost planned by scar dimensions can miss a substantial portion of the tumour bed, compromising local control. On the other hand, a substantial amount of breast tissue beyond the tumour bed can be unnecessarily irradiated, compromising cosmetic treatment results. Thus, the scar provides an inadequate landmark for radiation boost planning in breast-conserving therapy.