Ovarian suppression improves breast cancer outcomes in young patients
Young women with HER2-negative breast cancer had improved breast cancer-free interval (BCFI) rates following treatment with ovarian function suppression (OFS) in addition to tamoxifen or exemestane, according to a recent study.
“There was a meaningful clinical benefit in breast cancer outcomes with the addition of OFS to tamoxifen and some additional benefit from use of an aromatase inhibitor with OFS,” said the researchers.
Researchers analysed women aged <35 years with invasive early-stage HER2-negative breast cancer (n=442) from the SOFT* and TEXT** cohorts (n=5,707). In the SOFT cohort, women who were premenopausal following surgery were randomized to receive tamoxifen, tamoxifen plus OFS, or exemestane plus OFS, while in the TEXT cohort, women were assigned OFS in addition to either exemestane or tamoxifen.
Treatments were administered for 5 years and median follow-up was 6 and 5.6 years in the TEXT and SOFT groups, respectively. Ninety-four and 82 percent of the women in the SOFT and TEXT groups, respectively, underwent chemotherapy.
Compared with women aged ≥35 years, women aged <35 years had a higher risk of breast cancer event (hazard ratio [HR], 1.53), distant recurrence (HR, 1.52), and disease-free survival event (HR, 1.43).
In the SOFT trial, 5-year BCFI was highest among women aged <35 years receiving exemestane plus OFS (83.2 percent) after chemotherapy, followed by tamoxifen plus OFS (75.9 percent), and tamoxifen alone (67.1 percent). Similar results were demonstrated among women in the TEXT trial, with 5-year BCFI at 79.2 and 81.6 percent among women on tamoxifen plus OFS and exemestane plus OFS, respectively. [J Clin Oncol 2017;doi:10.1200/JCO.2016.72.0946]
“Such large absolute differences are compelling … and whether they will ultimately translate into future survival advantage is unclear as we await long-term follow-up,” said Drs Philip Poorvu and Ann Partridge from the Dana-Farber Cancer Institute and Harvard Medical School, Boston, Massachusetts, US, in a commentary. [J Clin Oncol 2017;doi:10.1200/JCO.2017.73.5662]
In the SOFT trial, women aged <35 years were less impacted by QOL symptoms (hot flushes, sweats, bone and joint pain) than those aged ≥35 years. The main symptom affecting QOL in women aged <35 years from SOFT was vasomotor symptoms (30- to 40-point worsening from baseline to 6 months), which improved over time in women who received OFS, and worsened among women receiving tamoxifen alone.
Women on OFS also experienced loss of sexual interest, while women on exemestane plus OFS experienced vaginal dryness, both of which did not improve with time. Bone and joint pain affected women on tamoxifen, tamoxifen plus OFS, and exemestane plus OFS. Early endocrine therapy discontinuation occurred in 19.8 percent of women aged <35 years.
The researchers advocated weighing the benefits vs the toxicities of OFS and acknowledged that the use of genomic testing, which was not employed in the current study, would help identify women who would most benefit from OFS.
“[The findings provide] important new data to support informed decision making for the youngest women with hormone receptor-positive early breast cancer ... judicious use of OFS represents an opportunity to improve breast cancer outcomes for our youngest patients, but we must select patients carefully, actively manage the consequences, and adapt to the individual patient’s experience and preferences,” said Poorvu and Partridge.