Each year, new cancer-related study results and data are released at the ASCO (American Society of Clinical Oncology) annual meeting held in Chicago. Today at ASCO 2014, long-awaited data from the SOFT and TEXT trials was released and these results may impact the treatment of young women diagnosed with early stage hormone receptor positive breast cancer. The importance of this data was made apparent by its inclusion in a plenary session oral presentation, which is reserved for only the most significant trial results.
The SOFT and TEXT trials compared an aromatase inhibitor – exemestane – to tamoxifen in early stage hormone receptor positive breast cancer, along with ovarian suppression. At a median follow-up of 5.7 years, the studies show that those participants receiving exemestane along with ovarian function suppression had a significantly reduced disease-free survival of 91.1% vs. 87.3% on tamoxifen and ovarian suppression. The breast cancer-free interval also shows an advantage for the exemestane arm, 92.8% vs. 88.8%. There were 4,690 women in the combined study results. You can download the original study at nejm.org at no cost.
You should know:
- 20% of the study participants were under 40 years old
- the median age was 43 years old
- 36% had tumors larger than 2 cm and 42% had positive lymph nodes
- ovarian function suppression was achieved by triptorelin (an injection that shuts down the ovaries) or, after six months, oophorectomy or ovarian irradiation
- overall survival benefit cannot be determined at this time – it’s too soon!
- side effects were mostly similar between the two arms (depression, hot flashes, musculoskeletal aches and pains, sexual side effects, osteoporosis) , but a little more severe in the exemestane group (31%) versus the tamoxifen group (29%). The tamoxifen group had higher incidence of thromboembolism (blood clot) and urinary incontinence.
- stopping treatment early occurred more in the exemestane group (15%) vs. tamoxifen (11%).
- more data on the tamoxifen only arm (without ovarian suppression) is expected to be reported at the San Antonio Breast Cancer Symposium in December
More Background
The SOFT (Suppression of Ovarian Function plus Tamoxifen or Exemestane) trial had three arms comparing the use of tamoxifen only, tamoxifen plus ovarian suppression, and exemestane plus ovarian suppression in premenopausal women with hormone receptor positive breast cancer. Ovarian suppression is the shutting down of a woman’s ovaries either by removing them, radiating them, or giving regular injections to stop their functioning. Tamoxifen works in premenopausal women by blocking the estrogen receptor and it is currently the standard of care in the United States. Exemestane is an aromatase inhibitor which blocks the production of estrogen in postmenopausal women.
TEXT (Tamoxifen and Exemestane Trial) contained two arms comparing ovarian suppression using an injection of triptorelin plus tamoxifen for five years versus ovarian suppression (using triptorelin) plus exemestane for five years. Ultimately, these trials hope to shed light on whether ovarian suppression is beneficial in premenopausal women and if so, which medication (tamoxifen or exemestane) should be prescribed with it.
The studies enrolled women with breast cancer between November 2003 and April 2011 at 510 centers in 27 countries.
Reported by Diana Chingos, a survivor of early onset breast cancer and a member of the Young Survival Coalition Research Think Tank. She lives in Los Angeles.
