[Assessment of the tumor bed dose in the conservative treatment of breast carcinoma].
We investigated the variations in the total dose given to primary tumor sites in breast irradiation after conservative surgery. Fifty patients consecutively submitted to CT for radiotherapy treatment planning were entered into this study. Treatment was planned with Varian Cadplan 2.61 for both whole breast irradiation (2 Gy/fraction, up to 50 Gy) and boost (2 Gy/fraction, up to 10 Gy) according to the ICRU 50 report. The doses were calculated localizing the tumor site with preoperative mammography or breast US, surgery description, the possible presence of clips and treatment planning CT. The doses to tumor volumes ranged 46.5 to 53.4 Gy [average: 50.7, standard deviation (SD): 1.47] with the tangential fields. The relative biological effects (RBE) ranged 55.2 to 64.9 Gy (average: 61.05, SD: 2.06). The total doses to tumor beds ranged 57.8 to 65.2 Gy (average: 61.6, SD: 1.63) and the relative RBE from 67.8 Gy to 79.4 Gy (average: 74.3, SD: 2.30). In conclusion, in our opinion, the assessment of radiotherapy efficacy in breast irradiation should be related also to tumor bed dose and not only to the prescribed dose. Indeed, its wide range (and, consequently, the marked differences seen in RBE) might be misleading, especially when the relationship between local relapse and boost usefulness is considered.
Bonetta
A
A
Servizio Dipartimentale di Radioterapia Oncologica, Arcispedale S. Maria Nuova, Reggio Emilia.
Lambertini
D
D
Zingoni
A
A
Morrica
B
B
D001943:Breast Neoplasms / Q000532:radiotherapy* / Q000601:surgery; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D011182:Postoperative Care; D011879:Radiotherapy Dosage