It has been not clinically determined whether TomoDirect was dosimetrically better than 3D-CRT for Asian patients with early breast cancer. Therefore, the objective of this study was to compare dosimetric parameters of TomoDirect and 3D-CRT in early breast cancer patients of an Asian cohort.

In breast cancer patients, helical TomoTherapy is not a suitable option since the gantry continuously rotates around the patient, and this technique can deliver low dose radiation to lungs that is associated with an occurrence of radiation pneumonitis. To avoid this inefficiency of beam usage, a TomoDirect option using static gantry positions combined with simultaneous couch translation and dynamic collimator modulation has been developed. In a pilot study, TomoDirect seemed particularly well suited for postoperative irradiation in breast cancer patients. TomoDirect achieved an optimal target volume coverage and coincident adequate normal tissue sparing in a dosimetric study. Clinical studies of TomoDirect in breast cancer patients are scarce and have been assessed only in small and retrospective series. Thus, we undertook a prospective study on the technical feasibility and toxicity of TomoDirect in breast cancer patients who received postoperative radiotherapy.

Inclusion Criteria:

1. histologically confirmed breast cancer after breast-conserving surgery
2. pT1-2N0
3. no evidence of distant metastasis
4. no previous malignancy
5. patient age, 20 - 80 years
6. Karnofsky performance score ≥ 70
7. adequate bone marrow, liver, and renal function (leucocytes > 4,000/mm3, hemoglobin > 10 g/dL, platelets > 100,000/mm3; serum bilirubin < 1.5 mg/dL, serum transaminase < 2.5 times the upper normal limit; serum creatinine < 1.5 mg/dL).
8. completion of scheduled chemotherapy

Exclusion Criteria:

1. carcinoma in situ of breast
2. distant metastasis
3. mastectomy
4. male
5. both breast cancer