[Preliminary results of whole breast helical tomotherapy with simultaneous integrated boost in the adjuvant treatment of breast cancer]. / Résultats préliminaires d'une tomothérapie hélicoïdale adjuvante avec boost intégré dans le cadre d'un traitement conservateur d'un cancer du sein.

ABSTRACT

PURPOSE: To evaluate the dosimetry and acute toxicity of helical tomotherapy for locoregional irradiation of patients after breast-conserving surgery. PATIENTS AND METHODS: Twenty breast cancer patients with breast-conserving surgery treated by helical tomotherapy have been studied. The median age was 49 (min 25, max 69). The whole breast, tumour bed and lymph nodes were prescribed 52.2 Gy, 63.8 Gy and 50.4 Gy, all in 29 fractions. The dose per fraction was 2.2 Gy to the boost, 1.8 Gy to the breast and 1.74 Gy to the lymph node volumes. The reproducibility was analysed by recording the daily shifts in x, y and z directions and roll rotation. All toxicities were described using the Common Terminology Criteria for Adverse Effects v3.0. RESULTS: Twenty-two tumours were irradiated. Six-eight percent were located in the inner quadrant. In 90 % of patients supraclavicular and internal mammary nodes were treated. The coverage of planning target volumes (PTV) was as follows PTV boost V107 = 0.3 % ± 0.5 SD, V95 = 98.4 % ± 1.9 SD; PTV breast -V107 = 7.8 % ± 17.3 SD, V95 = 96.8 % ± 2.2 SD; PTV LN V107 = 2.5 % ± 4.2 SD, V95 = 92.7 % ± 13.2 SD. The mean V20 of the homolateral lung was 18.9 % ± 3.5 SD. For left side lesion, the mean V30 of the heart was 0.9 % ± 0.8 SD. The mean V5 was V5 homolateral lung 73.1 % ± 11.8 ET, controlateral lung 38.9 % ± 21, heart (left side breast) 57.3 % ± 21, controlateral breast 15.5 % ± 9.6. Median shifts were as follow x-axis -0.04 mm (IC 95 -0.4 +0.38), y-axis -0.37 mm ± 5.51 (IC 95 -0.88 +0.14), z-axis 2.90 mm ± 5.42 (IC 95+2.4+3.4) and roll rotation 0.22 ± 1.10 (IC 95 -0.1+0.32). The treatment tolerance was acceptable with 1 definitive interruption couple of fractions before the end and 3 temporal interruptions for skin toxicity. No grade 3 or 4 toxicity. Ninety-five percent of patients experienced skin toxicity 45 % grade 2. There were 3 cases of oesophagitis. The median follow-up of presented series is 9.7 months and all of the patients are free of disease without any residual early or late toxicity. CONCLUSIONS: Helical tomotherapy can achieve full target coverage while protected to the heart and ipsilateral lung. This treatment was well tolerated and reproducible. However, the low doses to normal tissue volumes need to be reduced in future studies.