Radiotherapy with breast-conserving therapy plays a crucial role in the treatment of early breast cancer. However, optimal radiotherapy targets have been controversial. We therefore evaluated regional recurrence in breast cancer patients with one to three positive lymph nodes (LNs) treated with breast-conserving surgery (BCS) followed by whole-breast irradiation (WBI). From 1993 to 2010, 121 breast cancer patients with one to three positive LNs who underwent BCS followed by WBI were analyzed. All patients underwent radiotherapy with two tangential fields to the whole breast. To evaluate the radiation dose to the axillary LNs, we contoured axillary LNs area and evaluated the dose-volumetric parameters. The median follow-up time was 112.4 months (range, 15.6-248.1 months). The 5-year overall survival and disease-free survival rates were 95.6% and 86.6%, respectively. The 5-year regional recurrence-free rate (RRFR) was 97.4%. During follow-up, six patients had regional recurrence. The pathological T stage was the factor best associated with the 5-year RRFR using the log-rank test, with 100.0% in the pT1 cohort versus 94.7% in the pT2-4 cohort (P < 0.01). The radiation dose to the axillary LNs did not contribute to the RRFR. In conclusion, while the pathological T stage was the prognostic factor best associated with regional recurrence, few regional recurrences were observed in early breast cancer patients with one to three LNs treated with BCS followed by WBI. Unintentional radiation doses to the axillary LNs using standard WBI were not related to the RRFR after axillary dissection.
Keywords: breast cancer; breast-conserving therapy; radiotherapy.
© The Author 2016. Published by Oxford University Press on behalf of The Japan Radiation Research Society and Japanese Society for Radiation Oncology.