REPORTING FROM SABCS 2017
SAN ANTONIO (FRONTLINE MEDICAL NEWS) – Skip the perioperative aromatase inhibitor (AI) therapy in women with early stage hormone receptor-positive breast cancer, because it doesn’t make a difference in either time to recurrence or overall survival, British investigators advise.
Among nearly 4,500 women enrolled in the POETIC trial , time to recurrence (TTR) and overall survival (OS) were similar whether patients received AI therapy within 2 weeks of surgery or did not, reported John Robertson, MD , from the University of Nottingham, England, and his colleagues.
“There is no evidence of improved clinical outcome with perioperative aromatase inhibitor therapy,” he said at the San Antonio Breast Cancer Symposium.
The trial wasn’t all for naught, however, because it also provided further evidence that measuring Ki67 levels at baseline and at 2 weeks of therapy offer significant and independent prognostic information.
“If your baseline Ki67 is low, the prognosis is good, suggesting no need for 2 weeks of AI treatment and a second Ki67 measurement,” Dr. Robertson said.
However, if the Ki67 level is 10% or higher at baseline, a Ki67 measure after 2 weeks of AI therapy can be used to guide additional therapy.
“If the 2-week Ki67 is low, patients will do relatively well, with 8.4% recurrences, and may need no additional treatment beyond standard of care. If, however, your Ki67 at 2 weeks remains high, you have a poor prognosis with an almost 20% 5-year recurrence risk, and those patients should be considered for additional chemotherapy, and/or for trials looking at new agents,” he said.
POETIC was a randomized phase 3 trial in postmenopausal women with newly diagnosed estrogen– and progesterone receptor–positive invasive breast cancer. Patients were randomized on a 2:1 basis, respectively, to either perioperative therapy with an AI (letrozole or anastrozole) for 2 weeks, surgery, and an additional 2 weeks of AI treatment, or to surgery with no perioperative therapy within a 2-week window. Patients could receive further treatment in accordance with local practice.
Of 4,486 patients randomized, 4,480 were available for analysis, including 2,528 with both baseline and 2-week Ki67 in the perioperative therapy arm, and 678 with paired Ki67 readings in the no-therapy arm.
For the primary endpoint of TTR, the curves were superimposable, with 5-year TTR of 90.9% in the perioperative AI groups, and 90.3% in the no perioperative AI group, translating into an absolute difference of only 0.52%.
Similarly, there were no differences in OS at 5 years, at 89.0% vs. 89.5%, respectively (absolute difference, 0.51%), with survival curves virtually indistinguishable from one another.
The events contributing to TTR, including local or distant recurrence and breast cancer deaths were equally distributed between the trial arms.
For patients with high baseline Ki67 values (10% or greater) at both baseline and after 2 weeks of perioperative AI therapy, the 5-year absolute risk for recurrence was 19.6%, compared with 8.9% for those with high baseline but low 2-week Ki67 levels, and 4.5% for those with low levels at both time points. The hazard ratio for patients with high Ki67 at both time points was 2.22 (P less than .001).
The POETIC trial was supported by Cancer Research UK. Dr. Robertson did not report disclosure information.
SOURCE: Robertson J et al., Abstract GS1-03