Highest Risk of Discontinuing Endocrine Therapy Found Among Women With Symptoms From Previous Chemotherapy or Radiation for Breast Cancer

TON - February 2012 VOL 5, No 1 — February 29, 2012

A quality-of-life analysis of the large randomized NCIC MA. 27 trial shows that symptoms of endocrine therapy can be severe and have a negative effect on quality of life. The study also found that women with side effects from previous chemotherapy or radiotherapy before they start taking endocrine therapy are at higher risk for early discontinuation.

The most frequent symptoms of aromatase inhibitors are joint pain and hot flashes. For tamoxifen, the most frequent symptoms are hot flashes and vaginal dryness. Many women with breast cancer stop taking hormonal therapy even though it is known to prevent or delay recurrence. The study sought to examine quality of life in women taking aromatase inhibitors and reasons for treatment discontinuation.

“Treatment-related symptoms were comparable between anastrozole and exemestane. The frequency of side effects [from these two aromatase inhibitors] reported by patients was much higher than toxicity reported in clinical trials, and the percentage of moderate-to-severe symptoms was also much higher in patient reports than physician reports of adverse events. We found that symptom burden [of endocrine therapy] negatively affects quality of life,” said Lynne I. Wagner, MD, Northwestern University in Chicago, Illinois, who presented these results at the 2011 CTRC-AACR San Antonio Breast Cancer Symposium.

“Another major finding of this study was that women who have side effects from previous cancer treatment before initiating aromatase inhibitor therapy are at high risk for early discontinuation. These women may benefit from monitoring adherence and helping them to manage their side effects,” Wagner told listeners.

MA.27 was a large, prospective Eastern Cooperative Oncology Group (ECOG)-sponsored clinical trial that enrolled postmenopausal women with primary estrogen receptor–positive early breast cancer and randomized them to 5 years of treatment with 2 different aromatase inhibitors: anastrozole or exemestane. The original study showed that both drugs had comparable anticancer effects on recurrence or new primary breast tumor.

The quality-of-life analysis was based on 686 women who provided self-reported outcomes on symptoms using the 46-item PRO-FACT instrument—a disease-specific tool to evaluate side effects. Quality of life was assessed at baseline and again at 3, 6, 12, and 24 months following the initiation of endocrine therapy and included women who stopped taking hormonal therapy over the course of the trial.

Median age was 66 years; most of the women were Caucasian and had good performance status, and 25% to 30% had received prior chemotherapy.

The women reported the following new symptoms on endocrine therapy: joint pain (55%), weight gain (55%), hot flashes (40%), decreased libido (30%), breast sensitivity (42%), night sweats (28%), and mood swings (22%). The most common new symptoms were also the most common moderate-to-severe symptoms, Wagner explained. The only difference between the two hormonal therapies was in moderate-to-severe fatigue: 15% of the anastrozole group versus 24% of those who received exemestane.

Early discontinuation of hormonal therapy occurred in 10% by month 24 and 36% by 4.1 years. The prevalence of joint pain was not associated with discontinuation of hormonal therapy. Factors significantly related to early discontinuation were side effects at baseline from previous chemotherapy and radiotherapy, and the number of other medications patients were taking.

Commenting on this study, Patricia Ganz, MD, University of California Jonsson Comprehensive Cancer Center, Los Angeles, said that the strengths of this study were its size and that a disease-specific instrument was used to evaluate quality of life.

“The rates of new joint pain remain high and are no different between the two treatment arms. Hot flashes are also a problem. The higher rate of baseline symptoms affected discontinuation, showing that prior therapies can influence the degree of being bothered by new side effects and coming off of therapy. Uncontrolled symptoms can impact quality of life, and we need to focus on managing symptoms so that women who can benefit from hormonal therapy continue to take it,” Ganz said.

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