To assess reported endocrine treatment toxicity and consequent adherence in a cohort of women with hormone receptor positive breast cancer treated at a single centre, including the success of anti-estrogen switching due to toxicity
This was a single centre study at Royal Perth Hospital. Patients with hormone receptor positive breast cancer treated with curative intent were identified from the Breast Unit database. Patient reported treatment toxicity and adherence were obtained from case notes and clinic letters for endocrine therapy used. Outcome data were also obtained.
1921 patients were identified from the database from 1994-2011. 62% received tamoxifen as initial endocrine therapy, 13% letrozole, 18% anastrazole, and 5% ovarian suppression plus and aromatase inhibitor or tamoxifen. At last follow up 31% were continuing on their first line endocrine therapy, 20% had ceased as a result of completion of first line therapy, 11% had ceased as a result of a planned switch of therapy, 5% had ceased as a result of development of metastatic disease and 26% had ceased as a result of treatment related toxicity. The most frequently listed toxicity resulting in treatment cessation was hot flushes with this given as the main reason for cessation for 27% of those who ceased endocrine therapy.
Of the 490 patients who ceased first line endocrine therapy as a result of treatment toxicity, 316 (64%) trialled a second line of endocrine therapy. Of those, 160 (51%) were recorded as able to tolerate second line treatment sufficiently to continue treatment to completion, last recorded follow-up or development of further breast cancer related event.
A significant proportion of patients ceased first line endocrine therapy as a result of treatment toxicity. Trial of a second line of endocrine therapy where the first is ceased as a result of intolerance is worthwhile in this population.