Salvage radiotherapy for second oligo-recurrence in patients with breast cancer.

A new concept designated 'oligo-recurrence (OR)' has been proposed, which indicates one to several distant metastases/recurrences in one or more organs, which can be treated with local therapy, after the primary site of the cancer has been controlled. The purpose of this study was to assess the efficacy and toxicity of salvage radiotherapy (RT) for the second OR of breast cancer. The second OR was defined as once-salvaged patients with OR who had a second failure that was also detected as the state of OR. Twenty-one patients with second OR were treated with salvage RT and were retrospectively analyzed. The sites of the second OR were locoregional recurrence in 7 patients and distant metastasis in 14 patients. Salvage RT was performed at a median total dose of 60 Gy. Nineteen (90%) patients had an objective response. The median overall survival and progression-free survival (PFS) times were 41 and 24 months after salvage RT for the second OR, respectively. The 3-year local (in-field) control (LC) rates were 93%. The toxicities were mild; acute toxicities ≥Grade 3 were seen in one patient with Grade 3 dermatitis, and no late toxicity ≥Grade 2 was observed. In conclusion, salvage RT for the second OR was able to achieve a better LC rate and longer PFS time without inducing severe toxicity, and therefore may be a potentially effective modality for inducing long-term survival in select patients.