Continuing therapy with letrozole after 5 years of aromatase inhibitor (AI) therapy was no different than placebo in terms of quality-of-life (QOL) measures in patients with hormone receptor (HR)-positive breast cancer, according to a new study.
The MA.17R trial previously found that 10 years of AI therapy followed by letrozole in postmenopausal women with HR-positive breast cancer resulted in better disease-free survival compared with 5 years followed by placebo. The new analysis examined QOL outcomes in this same population.
The trial included 1,918 women, and 1,428 patients completed the baseline QOL assessment. QOL was measured using the Short Form-36 (SF-36) and the menopause-specific QOL (MENQOL), and the results were published in the Journal of Clinical Oncology.
The median age of the QOL study population was 65.8 years in the letrozole group and 64.7 years in the placebo group, and about half of patients in each group had positive node status at diagnosis. Most patients (71.0%) had received between 4.5 and 5.5 years of tamoxifen therapy prior to starting AI therapy. Compliance with QOL measures was above 85%.
At baseline, the groups had similar SF-36 physical component summary (PCS) and mental component summary (MCS) scores. The PCS score was 47.5 in the letrozole patients and 47.9 in the placebo patients; the score is normalized to the US population with a mean of 50, meaning these patients were only slightly below the norm. For MCS, the scores were slightly above the norm, at 55.5 and 54.8, respectively.
“For the main hypotheses addressing the change in mean QOL scores over time by intent to treat, no differences were observed between groups” for the SF-36 PCS or the MCS, wrote the study authors led by Julie Lemieux, MD, of Centre Hospitalier Universitaire de Québec in Québec City, Canada. Only the SF-36 role-physical subscale showed any difference on either of two statistical models used to compare the arms, with a deterioration of −3.2 points with letrozole compared with placebo (P = .009).
A significant interaction between time and treatment arm was observed for the bodily pain and role-emotional subscales of the SF-36; cross-sectional analyses showed no difference between the groups for the bodily pain score, while more women deteriorated on the role-emotional subscale with placebo vs letrozole (P = .01).
On the PCS, 27% of letrozole patients improved, 31% were stable, and 42% deteriorated; for placebo patients, these rates were 31%, 33%, and 36%, respectively (P = .05). No difference was seen in any of the four domains of the MENQOL.
“Our data found that in women who already tolerated 5 years of an AI, continuing therapy for another 5 years was not associated with a significant deterioration in QOL despite the fact that symptoms associated with estrogen deprivation (eg, vasomotor) improved slightly after stopping the AI,” the authors concluded. “These results, in combination with the data on disease control and toxicity, will assist healthcare providers and women with breast cancer to make an informed decision regarding continuing AI therapy beyond 5 years.”