Clinical Edge Journal Scan

Commentary: Endocrine therapy and mammography, May 2023

Dr. Roesch scans the journals, so you don't have to!

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Erin Roesch, MD

The use of endocrine therapy for prevention and adherence in the adjuvant setting is often affected by the patient's fear or experience of adverse side effects. Studies focused on finding the minimal effective dose of endocrine therapy while decreasing toxicity can lead to better uptake and improved adherence. The 10-year results from the TAM-01 trial, evaluating 5 mg tamoxifen daily (babytam) for 3 years among 500 women with ductal carcinoma in situ (DCIS), lobular carcinoma in situ, or atypical ductal hyperplasia, were recently presented. There was a 42% reduced risk for recurrence with low-dose tamoxifen vs placebo, and in the DCIS cohort there was a 50% reduction in recurrence risk with 3 years of low-dose tamoxifen.1

Serrano and colleagues performed a multicenter, double-blind, phase 2b randomized trial investigating various dosing schedules of exemestane (25 mg once daily, three times weekly, or once weekly) for 4-6 weeks before surgery, among 180 postmenopausal women with stage 0-II estrogen receptor–positive breast cancer (BC). Among adherent patients (89% of the population), 25 mg exemestane given three times weekly was noninferior to once-daily dosing in reducing serum estradiol (mean decrease of estradiol, -92% and -91%, respectively; difference in percentage change, 2.0%; P for noninferiority = .02), whereas once-weekly dosing was less effective. Adverse effects were similar, although owing to short exposure in this study, it will be important to explore longer-term differences because aromatase inhibitor–related toxicities may arise later on. These data support further exploration of alternative endocrine therapy schedules in the prevention setting, and also in adjuvant treatment for women who are unable to tolerate the standard dose.

Screening mammography reduces mortality from BC, and advances in techniques, such as digital breast tomosynthesis (DBT), have led to lower recall rates, and higher cancer detection rates compared with digital mammography (DM). Additionally, DBT has demonstrated better cancer detection compared with DM, notably among younger women and those with dense breast tissue.2 A retrospective study including over 2.5 million screening mammograms among women 40-79 years of age showed that, compared with DM, DBT had a lower recall rate (10.3% vs 8.9%; adjusted odds ratio [OR] 0.92; P < .001) and higher positive predictive value of recall (4.3% vs 5.9%; adjusted OR 1.33; P < .001), cancer detection rate (4.5 of 1000 vs 5.3 of 1000 screening mammograms; adjusted OR 1.24; P < .001), and biopsy rate (17.6 of 1000 vs 14.5 of 1000 screening mammograms; adjusted OR 1.33, P < .001) (Conant et al). These data add to the growing body of evidence showing superiority in BC screening with DBT vs DM and add support of this technique in routine clinical practice for our patients.

The initial treatment strategy for metastatic hormone receptor–positive (HR+)/human epidermal growth factor receptor 2–negative (HER2-) BC involves endocrine therapy in combination with a cyclin-dependent kinase (CDK) 4/6 inhibitor. The three PALOMA trials demonstrated progression-free survival (PFS) benefit with palbociclib plus endocrine therapy, and a pooled analysis of these studies reported consistent improvement in PFS with palbociclib plus endocrine therapy vs endocrine therapy alone in older patients.3 A retrospective study evaluated real-world outcomes of palbociclib plus letrozole vs letrozole alone among 796 women ≥ 65 years of age with HR+/HER- metastatic BC. First-line palbociclib plus letrozole compared with letrozole alone significantly improved median real-world PFS (22.2 vs 15.8 months; adjusted hazard ratio [HR] 0.59; P < .001) and overall survival (not reached vs 43.4 months; adjusted HR 0.55; P < .001). Real-world best tumor response rate was also higher (52.4% vs 22.1%; OR 2.0; P < .001) (Rugo et al). This study highlights the effectiveness of palbociclib plus letrozole in older adults with HR+/HER2- metastatic BC and the benefits of examining a real-world population that adds value to the existing data from randomized clinical trials.

Additional References

  1. De Censi A, Lazzeroni M, Puntoni M, et al. 10-year results of a phase 3 trial of low-dose tamoxifen in non-invasive breast cancer. Presented at the 2022 San Antonio Breast Cancer Symposium; December 6-10, 2022; San Antonio, Texas. Abstract GS4-08.
  2. Conant EF, Barlow WE, Herschorn SD, et al; Population-based Research Optimizing Screening Through Personalized Regimen (PROSPR) Consortium. Association of digital breast tomosynthesis vs digital mammography with cancer detection and recall rates by age and breast density. JAMA Oncol. 2019;5:635-64 doi: 10.1001/jamaoncol.2018.7078
  3. Rugo HS, Turner NC, Finn RS, et al. Palbociclib plus endocrine therapy in older women with HR+/HER2- advanced breast cancer: a pooled analysis of randomised PALOMA clinical studies. Eur J Cancer. 2018;101:123-13 doi: 10.1016/j.ejca.2018.05.017

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