Gene-Expression Biomarker Predicts Risk of Breast Cancer Recurrence

Biomarkers to improve the risk-benefit of extended adjuvant endocrine therapy for late recurrence in patients with estrogen-receptor-positive breast cancer would be clinically valuable.

Scientists from Massachusetts General Hospital (Boston, MA, USA) working with colleagues from other institutes, performed a prospective comparison study with 665 archival tumor blocks from a tissue bank from postmenopausal patients with ER-positive breast cancer. From these patients, the Oncotype DX 21-gene recurrence score (Genomic Health; Redwood City, CA, USA) and immunohistochemical prognostic model (IHC4; Genoptix; Carlsbad, CA, USA) values had already been derived.

The team compared the prognostic ability of the breast-cancer index (BCI) assay (bioTheranostics; San Diego CA, USA) to the other assay results. They carried out the BCI analysis in matched samples with sufficient residual ribonucleic acid (RNA) using two BCI models, cubic (BCI-C) and linear (BCI-L, using previously validated cutoffs. They assessed prognostic ability of BCI for distant recurrence over 10 years. They also tested the ability of the assays to predict early, 0 to 5 years and late, 5 to10 years, distant recurrence.

The BCI-L was the only significant prognostic test for risk of both early and late distant recurrence and identified two risk populations for each timeframe. It could help to identify patients at high risk for late distant recurrence who might benefit from extended endocrine or other therapy. While all three methods were able to predict recurrence risk in the first five years, only the BCI was able to accurately assess long-term recurrence risk. In fact, the BCI was able to clearly distinguish 60% of patients whose risk was quite low from 40% who continued to be at significant long-term risk.

Dennis C. Sgroi, MD, the lead author of the study said, "We know that more than half the instances of recurrence in ER-positive breast cancer occur after five years of therapy with tamoxifen or anastrozole, so these findings are highly relevant to clinical management. Since the BCI identifies two distinct risk groups, it may provide a much-needed tool in determining those patients who need extended hormonal therapy and those who may be spared its well-known adverse side effects.” The study was published on September 12, 2013, in the journal Lancet Oncology.

Related Links:
Massachusetts General Hospital
Genomic Health
Genoptix