One of the nine Oncotype DX studies being presented at the 2014 American Society of Clinical Oncology (ASCO) Annual Meeting taking place in Chicago, these data will be presented on 2 June 2014.

This new study analyzed 668 and 1065 patients from the original NSABP B-14 and B-28 trials, respectively. Median follow-up of 13.9 years (B-14) and 11.2 years (B-28) determined that the Oncotype DX Recurrence Score results were significantly associated with distant recurrence after five years in patients whose tumors had high estrogen receptor expression.

Specifically, in the NSABP B-14 patients, the association of the continuous Recurrence Score with distant recurrence after five years in the higher ER patients was significant (p=0.004) after adjustment for age, grade and tumor size.

The results suggest that extending tamoxifen beyond five years may be most beneficial in patients with high and intermediate Recurrence Scores with higher quantitative ER expression. Conversely, patients with low Recurrence Score results would be expected to have limited benefit from extended tamoxifen beyond five years due to much lower risk for late distant recurrence.

Genomic Health chief medical officer Phil Febbo said that since its introduction a decade ago, the Oncotype DX breast cancer test has helped patients and their physicians around the world make better informed treatment decisions.

"These new data emphasize our ability to guide breast cancer treatment decisions throughout the patient’s cancer journey, addressing additional questions to make cancer care smarter," Febbo added.