Poster & Mini Oral Joint 2016 COSA and ANZBCTG Annual Scientific Meeting

Adherence to endocrine therapy in a real world cohort of women with early breast cancer treated at two Sydney cancer centres. (#199)

Sara SW Wahlroos 1 , Stephen Della-Fiorentina 1 , Diana Adams 1 , Brett Hamilton 1 , Kelly Mok 2 3 , Belinda Kiely 1
  1. Medical Oncology, MacArthur Cancer Therapy Centre, Sydney, NSW, Australia
  2. Medical Oncology, Liverpool Cancer Therapy Centre, Sydney, NSW, Australia
  3. Medical Oncology, Liverpool Cancer Therapy Centre, Sydney, NSW, Australia


We sought to determine the proportion of women with early breast cancer (EBC) who stop/switch endocrine therapy (ET) and the reasons for these changes.


We identified women aged ≥50 years, diagnosed with stage 1-3, ER/PR positive EBC and starting ET between January 2008 and June 2010. We recorded: demographics; ET type, duration, and toxicity; recurrences and survival from EBC diagnosis.


Of 217 women with ER/PR positive EBC, 172 (79%) started ET. Median age at diagnosis was 62 years (range 50-89), 148 (87%) were post-menopausal and 69 (40%) received adjuvant chemotherapy. Reasons for not starting ET were: not recommended by doctor (46%), fear of toxicity (30%), and patient declined (12%). The most commonly prescribed first-line ET was anastrozole (59%), followed by Tamoxifen (26%). The median duration on ET was 60 months (range 1-92), with 66 women (38%) completing 5 years, and another 47 (27%) continuing >5 years. The number of ET agents received in the first 5 years was: 1 (58%); 2 (30%); and ≥3 (12%). Of women starting aromatase inhibitors (AI), 41% changed ET due to toxicity; 46% switched to Tamoxifen, 23% switched to another AI and 14% stopped ET. 59% of women starting AI completed ≥5 years of ET. Of women starting tamoxifen, 55% changed ET and 45% completed ≥5 years of ET. The most common reasons for stopping first-line ET were arthralgia (28%) and hot flushes (9%). With 5.4 years median follow-up, 18 women (7%) had a recurrence, (8 on ET, 5 after stopping ET, and 5 who never started ET), and 21 women (10%) have died.


One third of women recommended adjuvant ET never start or stop prematurely. Measures to improve uptake and adherence in these women are important to reduce BC recurrences.