The risk of recurrence (ROR) score provides clinically meaningful prognostic information after postmenopausal women with early-stage breast cancer complete 5 years of tamoxifen therapy, according to a report published online Oct. 27 in Journal of Clinical Oncology.
The ROR score is derived from a quantitative assessment of a tumor’s expression of 46 genes related to breast cancer plus a measure of the tumor’s size. In this study, it was added to the Clinical Treatment Score, a standard prognostic tool that takes into account nodal status, tumor size and grade, patient age, and treatment modalities, said Ivana Sestak, Ph.D., of the Centre for Cancer Prevention, Wolfson Institute of Preventive Medicine, Queen Mary University, London, and her associates.
To examine the usefulness of the ROR score in assessing risk for late recurrence of breast cancer, researchers analyzed combined data from two large clinical trials involving 2,137 postmenopausal women with early-stage hormone receptor–positive breast cancer who received 5 years of endocrine therapy but no chemotherapy and were followed for a further 5 years. There were 148 distant recurrences during that time.
Women classified by ROR score as high risk were 6.9 times more likely to develop a late recurrence than were those classified as low risk, and women classified by ROR score as intermediate risk were 3.3 times more likely to develop a late recurrence. The addition of ROR score to the Clinical Treatment Score reclassified 32 women as high risk, and those women did go on to develop a late recurrence. Similarly, adding to ROR score to the Clinical Treatment Score reclassified three women as low risk, and those women did not go on to develop a late recurrence, the investigators said (J. Clin. Oncol. 2014 Oct. 27 [doi:10.1200/JCO.2014.55.6894]).
In particular, the ROR score was helpful in assigning a “low-risk” designation to women who had node-negative and node-negative/HER2-negative disease, even though some of them had large tumors. These women could safely be spared from further endocrine therapy. Likewise, the ROR score was helpful in identifying women at high risk of recurrence who may wish to extend endocrine therapy beyond 5 years, Dr. Sestak and her associates said.