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Anastrozole, tamoxifen associated with different symptoms in women with DCIS
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SAN ANTONIO — Postmenopausal women with ductal carcinoma in situ who received anastrozole plus radiation therapy after lumpectomy experienced similar quality-of-life outcomes as those who received tamoxifen plus radiation therapy after lumpectomy, according to study results presented at San Antonio Breast Cancer Symposium.
However, differences emerged between treatment groups with regard to specific symptoms, an analysis of patient-reported outcomes from the NRG Oncology/National Surgical Adjuvant Breast and Bowel Project B-35 trial showed.
Patricia A. Ganz
“Twelve or thirteen years after we designed this trial, we know a lot more about these two drugs,” Patricia A. Ganz, MD, director of the Center for Cancer Prevention & Control Research at Jonsson Comprehensive Cancer Center and distinguished professor in the schools of medicine and public health at University of California, Los Angeles, said during a press conference. “With this information on patient-reported outcomes — as well as [efficacy outcomes] — physicians and patients can now make much more personalized decisions about which of these effective agents they should select.”
The B-35 trial included 3,104 postmenopausal women with ER-positive or PR-positive ductal carcinoma in situ (DCIS) who underwent lumpectomy. Researchers assigned women to breast radiation therapy plus 5 years of either anastrozole 1 mg/daily or tamoxifen 20 mg/daily.
Breast cancer-free interval — defined as the time to any breast cancer event — served as the primary endpoint.
Previously reported results showed anastrozole was associated with improvement in the rate of 10-year disease-free interval (93.5% vs. 89.2%; HR = 0.73; P = .03).
When researchers stratified results by patient age (< 60 years vs. ≥ 60 years), results showed the benefit associated with anastrozole was statistically significant among younger patients (HR = 0.52; P = .003) but not older patients (HR = 0.95).
The quality-of-life substudy, which used an intention-to-treat analysis, included 1,193 patients (anastrozole, n = 592; tamoxifen, n = 601). Slightly more than half of the total cohort (53.1%) was aged 60 years or older. Characteristics of patients in the substudy were comparable between treatment groups and reflected the patient population from the full trial, Ganz said.
Ganz and colleague used five instruments to assess patient-reported quality-of-life and symptom data prior to randomization, every 6 months during the 5-year treatment protocol, and again 1 year after treatment. Symptoms measured included hot flashes, vaginal dryness, and muscle and joint aches and pains.
The researchers used a mixed model for repeated measures analysis adjusted for baseline scores, time point and age. Researchers censored patients with protocol events.
At 5 years, results showed no difference between anastrozole- and tamoxifen-treated women with regard to quality-of-life outcomes, but they did reveal differences related to specific symptoms.
Women assigned tamoxifen experienced greater severity of vasomotor symptoms (P = .01), a composite of hot flashes and night sweats. Women assigned anastrozole experienced more intense musculoskeletal pain (P = .0006) — particularly at the 6-month to 24-month time points — as well as more severe vaginal problems and slightly worse sexual functioning.
All symptoms were worse in women aged younger than 60 years.
Still, Ganz emphasized the instrument researchers used asked patients to rate symptoms on a scale of one to four, ranging from slight to extreme.
“Scores were between one and two, so even though symptoms may be more frequent [in one group], we are talking about modest severity,” Ganz said.
Both drugs appeared safe, and neither was associated with worsening of physical health, emotional health or depression.
The findings will better inform clinicians and patients about the potential benefits of each agent given their age and other health factors, researchers said.
“I think this really speaks to the personalization of treatment,” Ganz said. “We talk about precision medicine and precision with the tumor. This is precision with the whole patient.” – by Mark Leiser
Reference:
Ganz PA, et al. Abstract S6-04. Presented at: San Antonio Breast Cancer Symposium; Dec. 8-12, 2015; San Antonio.
Disclosure: Ganz reports no relevant financial disclosures. Please see the abstract for a full list of all researchers’ relevant financial disclosures.