SUMMARY: Breast cancer is the most common cancer among women in the US and about 1 in 8 women (12%) will develop invasive breast cancer during their lifetime. Approximately, 233,000 new cases of invasive breast cancer will be diagnosed in 2014 and 40,000 women will die of the disease. Approximately 75% of patients with breast cancer are hormone receptor positive (Estrogen Receptor/Progesterone Receptor positive) and this is a predictor of response to endocrine therapy. In premenopausal woman, the ovary is the main source of estrogen production, whereas in postmenopausal women, the primary source of estrogen is the Aromatase enzyme mediated conversion of androstenedione and testosterone to estrone and estradiol in extragonadal/peripheral tissues.
Presently available therapies include Tamoxifen and other Selective ER Modulators, which modulate ER alpha activity, Aromatase Inhibitors and Ovarian ablation that decrease estrogen production and FASLODEX® (Fulvestrant) that down regulates Estrogen Receptor. Aromatase Inhibitors (AI’s) are often prescribed, due to their superiority over Tamoxifen, for postmenopausal women with Hormone Receptor positive breast tumors, in adjuvant as well as metastatic settings. AI’s however, are not effective in premenopausal women, as these individuals derive their estrogen mainly from ovaries and not extragonadal tissues. The 2000 Early Breast Cancer Trialists’ Collaborative Group (EBCTCG) overview, as well as subsequent studies comparing adjuvant ovarian ablation/suppression with adjuvant chemotherapy in premenopausal women with hormone positive breast tumors, have demonstrated similar magnitude of benefit. The TEXT (Tamoxifen and Exemestane Trial) and SOFT (Suppression of Ovarian Function Trial) are two phase III randomized trials, conducted at the same time and included premenopausal women (average age was 43 years) with hormone receptor positive early breast cancer. In the joint analysis of these two trials in which 5738 women were enrolled, the authors set out to answer 2 important questions – whether adjuvant AI improves outcomes in this patient group when their Ovarian Function is suppressed and whether there is any benefit with Ovarian Function suppression in premenopausal women suitable for adjuvant Tamoxifen. TEXT randomized patients (N=2672) within 3 months of surgery to 5 years of AROMASIN® (Exemestane) plus Ovarian Function Suppression (OFS) or 5 years of Tamoxifen plus OFS. The SOFT study randomized patients (N=3066) to 5 years of AROMASIN® plus OFS or 5 years of Tamoxifen plus OFS or 5 years of Tamoxifen alone. OFS choices included oophorectomy, ovarian irradiation or 5 years of TRELSTAR® (Triptorelin), a GnRH (Gonadotropin Releasing Hormone) agonist. The primary endpoint of these two studies was Disease Free Survival (DFS). In this joint analysis the outcomes for 4690 women randomized to receive AROMASIN® plus OFS or Tamoxifen plus OFS for 5 years, were analyzed. The 5 year Disease Free Survival was 91.1% in the AROMASIN® plus OFS group and 87.3% in the Tamoxifen plus OFS group (HR=0.72, P<0.0002). Compared to patients receiving Tamoxifen plus OFS, AROMASIN® plus OFS reduced the relative risk of premenopausal women developing a subsequent invasive breast cancer by 28% and the relative risk of breast cancer recurrence by 34%. The authors concluded that this largest joint analysis, evaluating adjuvant AI therapy with OFS in premenopausal women with Hormone receptor positive breast cancer, has demonstrated that 5 years of highly effective adjuvant endocrine therapy without chemotherapy can result in excellent outcomes. Further, AROMASIN® may be better than tamoxifen, when given with Ovarian Function Suppression. Pagani O, Regan MM, Walley B, et al. J Clin Oncol 32:5s, 2014 (suppl; abstr LBA1)
Bottom Ad
Advertisement
Subscribe
