Retrospective review of genomic testing in breast cancer: Does it improve outcome?

PURPOSE: Tumor genomic testing has become widely available in many clinical settings. However, we do not yet understand how to best harness the information yielded from this testing. We retrospectively investigated the clinical courses of 24 patients who underwent tumor genomic testing to determine whether targeted therapy is associated with improved progression free survival (PFS) compared to standard therapy.

METHODS: The patient population comprised metastatic breast cancer patients who underwent tumor genomic testing (testing biopsy specimens of primary or metastatic lesions for 50 commonly mutated genes) at our institution between September 1, 2010 and June 1, 2015. Through retrospective chart review, we compared PFS for those patients who received targeted therapy based on their genomic testing results, and those who did not.

RESULTS: The median PFS was 5.7 months for those who received targeted therapy versus 5.4 months for those who did not (p = 0.6). There was no statistically significant difference in PFS between the two groups.

CONCLUSIONS: In this relatively small group, the PFS was markedly similar between the targeted therapy and standard therapy groups. Currently, there is no clear evidence to incorporate tumor genomic testing into routine clinical practice.