Aromasin demonstrates efficacy against breast cancer recurrence

7 Apr 2016

Premenopausal women with hormone receptor-positive, HER2-negative breast cancer may benefit from exemestane (Aromasin) plus ovarian function suppression (OFS) versus tamoxifen with or without OFS, analysis of recurrence-risk data from the TEXT and SOFT trials has indicated.

Important results leading to individual decision making

"The TEXT [Tamoxifen and Exemestane Trial] and SOFT [Suppression of Ovarian Function Trial] results provide new adjuvant endocrine therapy options for premenopausal women who require individual decision making considering potential benefits and adverse effects," the study authors wrote.

The analysis, which looked 4,891 premenopausal patients with HER2-negative disease from the TEXT and SOFT trials, revealed different treatment effects on 5-year BCFI using Cox analysis and subpopulation treatment effect pattern plot (STEPP) methodology. This composite measure of recurrence risk may not be broadly applicable outside the TEXT and SOFT cohorts, said the investigators.

Age younger than 35 years, four or more positive lymph nodes, and grade 3 tumor were the most influential features contributing to a high composite risk relative to their referent categories, said the investigators.

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Results of the analysis 

"On average, the magnitude of absolute benefit with exemestane plus ovarian function suppression versus tamoxifen with or without ovarian function suppression was as great as the benefit with 5 years of aromatase inhibitor versus tamoxifen for postmenopausal women -- approximately 3% to 4% at 5 years," said the investigators. "However, it ranged widely from less than 1% to greater than 15% depending on risk of recurrence, as quantified by the composite measure of recurrence risk." In particular:

  • Those with a high recurrence risk may experience a 10% to 15% improvement in the 5-year breast cancer-free interval (BCFI) with aromatase inhibitor (AI) exemestane plus ovarian function suppression.
  • Those at intermediate risk may experience an improvement of at least 5% with the same regimen, according to Meredith M. Regan, ScD, of Dana-Farber Cancer Institute in Boston, MA, and colleagues. This benefit of exemestane plus OFS over tamoxifen with or without OFS was moderate, "requiring a balanced discussion of benefits and adverse effects," such as menopausal symptoms and sexual effects, they said.
  • Patients at lowest risk of recurrence had minimal benefit with exemestane plus ovarian function suppression, the study showed.
  • In SOFT patients who remained premenopausal after chemotherapy, the benefit of tamoxifen plus OFS versus tamoxifen alone was apparent at the highest composite risk, the analysis showed.
  • Women in the SOFT no-chemotherapy cohort -- for whom composite risk was lowest on average -- did well with all endocrine therapies, said the investigators.
  • TEXT patients not receiving chemotherapy and with the lowest composite risk did well with both treatments
  • For some premenopausal women at low risk of recurrence, the STEPP analysis further supported the option of adjuvant tamoxifen alone without chemotherapy, Regan and colleagues reported.

“The higher the risk, the bigger the absolute benefit from therapy”

Individualized treatment decisions need to be made carefully, the investigators cautioned. "Consideration of preference, tolerance, and cost should also inform the decision-making process in this subset of patients at intermediate risk of recurrence.

"In the absence of predictive biomarkers, consideration of a patient's prognosis, as illustrated by STEPP analysis of a composite measure of recurrence risk in the TEXT and SOFT populations, is integral to this decision making."

While ovarian function suppression and aromatase inhibitor therapy is a viable option for premenopausal patients with early-stage breast cancer, the benefit from this approach needs to be weighed against the side effects, Virginia Kaklamani, MD, from the University of Texas Health Science Center San Antonio, TX., who was not affiliated with the study, commented. "It will also be very important to wait for overall survival data” she added.

Accurately identifying patients' risk of recurrence will help optimize therapy, said Kaklamani, noting that in patients with low risk of recurrence "there is very little we can do to improve on that." However, she pointed out, "the higher the risk, the bigger the absolute benefit from therapy. For example, a 50% relative benefit in a patient with a 5% risk of recurrence is 2.5%. But a 50% relative benefit for a patient with a 50% risk of recurrence is 25%.

Source: MedPage Today

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