Young people with early-stage breast cancer: What we learned at ASCO

Several studies presented at the 2022 Annual Meeting of the American Society of Clinical Oncology focused on ways to better tailor treatment for premenopausal women with early-stage breast cancer, especially those with hormone receptor-positive breast cancer.

Updates on treatment options support the continued use of ovarian function suppression, or OFS, in younger women. Among the studies presented:

• An extended subgroup analysis of the TEXT and SOFT clinical trials that shows aromatase inhibitors plus ovarian function suppression is effective against high-risk, early-stage breast cancers.
• New findings from the ASTRRA trial that suggest two years of OFS medications plus tamoxifen may be enough treatment for some types of breast cancer.

Background on the studies

Younger people with early-stage hormone receptor-positive (HR+) breast cancer increasingly have more treatment options. Tamoxifen has been a mainstay, and more recent research supports the use of aromatase inhibitors for early-stage breast cancers. Both types of medication work more effectively when given with an ovarian function suppressor medication.

Background on ASTRRA

Medications that suppress ovarian function have been a powerful addition to the treatment landscape in breast cancer. When hormones drive cancer growth, as they do in hormone receptor-positive breast cancers, pausing estrogen production can help prevent cancer from returning. But because HR+ breast cancers can return many years after treatment, a key question remains: is two years of OFS treatment enough to stop recurrences?

That question matters because these medications have significant benefit but also have significant side effects. Those sometimes lead people to stop use before the recommended five years of treatment end. For this reason, research is ongoing to determine whether a shorter course of treatment will provide the same level of benefit.

Results from ASTRRA

New findings reported at ASCO suggest that two years may be sufficient for some. The ASTRRA trial conducted in Korea found that ovarian suppression medication taken for two years by women with hormone receptor-positive early-stage breast cancer had a significant benefit in helping people stay cancer-free.

The median age of the 1,282 women in the trial was 40. All participants were age 45 or under. Slightly more than half had cancer in the lymph nodes, and 14% had HR+ and HER2-positive disease. The study participants were randomly assigned to one of two groups. One group received tamoxifen for five years along with the ovarian function suppressor drug goserelin (Zoladex) for two years. The other group took tamoxifen alone for five years.

After eight years, the group receiving goserelin combination had 5.2% higher breast cancer-free survival over the group not taking it – 85.4% versus 80.2%. There was no statistically significant difference in overall survival, or how long people lived, in part because over 95% of participants in both groups remained alive at eight years.

Currently, the OFS drug goserelin is recommended for five years. This news suggests that two years might be enough to be beneficial. Dr. Hee Jeong Kim, MD, PhD, who presented the ASTRRA results cautioned that, while two years might be enough in older premenopausal women, more research is needed, especially in people under 40.

Background and results from SOFT and TEXT

Research presented in 2021 at the San Antonio Breast Cancer Symposium, showed that aromatase inhibitors, when combined with OFS, are effective in reducing recurrence of early-stage breast cancer. Previously, these drugs had been used only in women who have gone through menopause. Findings from the SOFT and TEXT clinical trials support the use of aromatase inhibitors plus OFS over tamoxifen plus OFS.

A new analysis of SOFT and TEXT looked only at high-risk participants and extended the timeframe from two to five years. High risk was defined as a person who had four or more lymph nodes with cancer or some combination of positive lymph nodes, grade, tumor size, and Ki-67 score. The study participants all had HR+, HER2- early-stage breast cancer. The research team found that the original results held up for this group, and that the benefit of aromatase inhibitors plus OFS persisted over time.

What this means for you

Both tamoxifen and aromatase inhibitors are highly effective in keeping cancer from coming back. When these medications are combined with ovarian function suppression, people stay cancer-free longer.

If you have HR+ breast cancer, talk with your oncologist about your options and which one makes most sense for your specific situation. Ask about possible side effects, and consider what matters most to you, especially when you consider family planning and sexuality.

Many people find it hard to continue to take medications for years on end for a variety of reasons, or they find particular side effects very hard to bear. The more your doctor understands your priorities and your concerns, the better they will be able to suggest an effective treatment plan for you. Factors such as the cancer’s HER2 status, your age, and the number of lymph nodes with cancer involved can all affect your options.