Long-term outcomes of oligometastatic breast cancer patients treated with curative intent: an updated report.

BACKGROUND

Oligometastatic breast cancer (OMBC) is characterized by limited metastatic tumor numbers and sites. We have reported a 20-year overall survival (OS) rate and relapse-free rate (RFR) of 34.1% and 27.4%, respectively, in a retrospective analysis of OMBC patients treated with curative intent including a multidisciplinary approach. Metastatic breast cancer (MBC) is generally incurable; however, OMBC might be a potentially curable subset. The previous analysis included isolated locoregional recurrence (ILRR) cases, which differs from distant metastasis in treatment strategies. Therefore, in this study, we excluded ILRR cases and provided an update on clinical outcomes. We also performed a detailed subgroup analysis of OMBC patients by introducing new prognostic variables.

METHODS

Data of 73 OMBC patients, including 10 ILRR cases, treated in our institution between 1980 and 2010 were retrospectively analyzed. OMBC was defined as the presence of metastatic lesions in 1-2 organs, < 5 lesions per metastasized organ, and lesion diameter < 5 cm.

RESULTS

The median follow-up duration was 151 (range 12-350) months. Twenty-eight (44%) patients received local therapy. Excluding ILRR cases, the OS rates were 28.3% and 18.9% and RFRs were 26.7% at 20 and 25 years, respectively. In multivariate analysis, single-organ involvement and three or fewer metastatic lesions per organ were associated with a longer progression-free and relapse-free interval (RFI).

CONCLUSIONS

Relapse-free interval reached a plateau after 20 years at approximately 25% probability. Patients with long-term survival without disease relapse are considered cured. Curative-intent therapy should be considered for OMBC patients, especially those with low tumor volume.