Harold J. Burstein, MD
“There is a tremendous interest in longer aromatase inhibitor therapy. The Oxford Overview data, presented at ASCO, show the substantial risk of recurrence in years 5 to 15, despite an initial 5 years of adjuvant endocrine treatment. “Women with lower-risk breast cancer will be less inclined to extend aromatase inhibitor therapy, while those at higher risk might consider extended treatment,” stated Harold J. Burstein, MD, ASCO expert in breast cancer. “We are not at the point where we are saying women with hormone receptor–positive postmenopausal breast cancer should be on these drugs for the rest of their lives,” he added.
“Ten years of any therapy is a long time. Fortunately, most women tolerate extended treatment reasonably well, with few side effects. Now, women can talk with their clinical team and make informed decisions to extend adjuvant endocrine therapy or not,” Dr. Burstein declared. Dr. Burstein added, “The good news is, our patients readily understand these trade-offs and are very capable of sharing in this choice.”
Ian Smith, MD
Formal discussant of this trial Ian Smith, MD, of the Royal Marsden NHS Foundation Trust and Institute of Cancer Research, London, said the benefits of 10 years of hormonal therapy had been well established in this population, but he expressed reservations about extending therapy for another 5 years.
In his view, the results are especially relevant for women at high risk of recurrence who can tolerate the side effects of aromatase inhibitor treatment. These women may want to extend aromatase inhibitor for an extra 5 years. He said that another abstract at the meeting identified the following risk factors for late recurrence after 5 years of endocrine therapy: node positivity, larger tumor size, higher grade, and Ki67 status.1
“How should clinicians react to these results? The reduction in contralateral breast cancer contributes significantly to the disease-free survival benefit in this trial. But the difference is only 1.1% for distant recurrence, and so far there is no survival benefit. These data would not sustain a novel adjuvant therapy,” Dr. Smith told listeners.
Putting on his “clinical scientist hat,” he added: “We need to develop an algorithm based on both clinical and genomic parameters for risk of late relapse, so the majority of patients who don’t need prolonged therapy can be identified.”
Dr. Smith continued: “As a pragmatic clinician, these data do not justify telling all our patients to continue endocrine therapy beyond 10 years. But in a patient with high-risk features who has thrown off unpleasant early side effects, I would discuss the data and help her make a choice.” ■
Disclosure: Drs. Burstein and Smith reported no potential conflicts of interest.
1. Pan H, Gray RG, Davies C, et al: Predictors of recurrence during years 5-14 in 46,138 women with ER+ breast cancer allocated 5years only of endocrine therapy. 2016 ASCO Annual Meeting. Abstract 505. Presented June 6, 2016.
Five years of aromatase inhibitor as upfront therapy or after tamoxifen is the current standard of care for postmenopausal women with early hormone receptor–positive breast cancer. A new trial suggests that extending aromatase inhibitor therapy with letrozole for an additional 5 years may improve...