Gene assay identifies breast cancer patients who can safely skip chemo
The findings, presented at the European Cancer Congress (ECC) 2015 in Vienna, Austria, are from the TAILORx trial (Trial Assigning Individualized Options for Treatment) (n=10,273) designed to validate and refine the clinical usefulness of the Oncotype DX Recurrence Score in guiding treatment in patients with ER-positive, HER2-negative, axillary node-negative breast cancer. [ECC 2015, abstract 5LBA; N Engl J Med 2015, doi: 10.1056/NEJMoa1510764]
“Among 1,626 low-risk patients with recurrence scores of 0 to 10 who were treated with endocrine therapy alone, clinical outcomes were excellent at 5 years, with a low risk of distant recurrence of 1 percent,” reported lead investigator Dr. Joseph Sparano of the Albert Einstein College of Medicine, New York, NY, US.
In this low-risk cohort, the rate of 5-year invasive disease-free survival, recurrence-free survival (RFS), distant RFS and overall survival was 93.8 percent, 98.7 percent, 99.3 percent and 98.0 percent, respectively.
“Patient age and tumour grade had no significant impact on recurrence risk. The rates of recurrence were low irrespective of histologic grade,” said Sparano. “Since adjuvant chemotherapy prevents mostly early recurrences within 5 years, our results suggest that chemotherapy may be spared in this patient population.”
“The prospective TAILORx trial provides the highest level of evidence supporting the clinical utility of the 21-gene assay in patients with ER-positive, HER2-negative, axillary node-negative breast cancer,” he continued. “The findings confirm expert opinion-based clinical guidelines that recommend using the recurrence score to risk-stratify patients for adjuvant chemotherapy.”
The trial also included 6,897 patients with mid-range recurrence scores of 11-25, who were randomized to receive chemotherapy plus endocrine therapy or endocrine therapy alone. Continued follow-up will address the question of whether chemotherapy improves outcomes in these intermediate-risk patients.
The recurrence score ranges used in TAILORx were different from those originally used to define low (0-10 vs <18) and intermediate risk (11-25 vs 18-30). According to the investigators, this was to minimize the potential for undertreatment of the study participants.
“Previous studies showed that 7.3 percent of patients with a recurrence score of 11 experienced distant recurrence at 10 years. For those with a recurrence score of 25, the 10-year rate of distant recurrence was 16.1 percent,” Sparano noted. “While chemotherapy has demonstrated clear benefits in patients with high recurrence scores of ≥31, the benefit in patients with intermediate or low recurrence scores has been uncertain.”