A case of metachronous bilateral breast cancer with bilateral radiation pneumonitis after breast-conserving therapy.

We report a patient with metachronous bilateral breast cancer who has twice developed radiation pneumonitis after breast-conserving therapy for each breast. The patient was a 48-year-old woman, who presented with Stage I right breast cancer. After wide excision of the right breast tumor and dissection of level I axillary lymph nodes, systemic therapy with oral 5-FU and tamoxifen was started. Subsequently, tangential irradiation with a total dose of 50 Gy in 25 fractions was given. Seven months after irradiation, she developed respiratory symptoms and radiation pneumonitis was diagnosed. The symptoms resolved with oral prednisolone. Thirty months after the right breast cancer treatment, Stage I left breast cancer was diagnosed. After wide excision of the left breast tumor and partial removal of the level I axillary lymph nodes, the same oral systemic chemo-hormonal therapy was initiated. Thereafter, tangential irradiation with a total dose of 50 Gy in 25 fractions was given. Four months after irradiation, she developed respiratory symptoms. A chest X-ray showed an area of increased density in the left lung consistent with radiation pneumonitis. The symptoms were mild and they improved spontaneously without medication. Although there is insufficient evidence to justify or withhold whole breast radiation therapy from patients with a history of contralateral breast cancer and radiation pneumonitis, it is essential to discuss the adequacy of whole breast irradiation and the possibility of alternative approaches, such as breast-conserving surgery without irradiation or partial breast irradiation for this rare condition.