Endocrine treatment and incidence of relapse in women with oestrogen receptor-positive breast cancer in Europe: a population-based study

Breast Cancer Res Treat. 2020 Sep;183(2):439-450. doi: 10.1007/s10549-020-05761-9. Epub 2020 Jul 10.

Abstract

Purpose: Endocrine therapy (ET) is the mainstream adjuvant treatment for ER-positive breast cancer (BC). We analysed 9293 ER-positive BC patients diagnosed in nine European countries in 2009-2013 to investigate how comorbidities at diagnosis, age, stage and subtype affected ET use over time, and relapse.

Methods: Adjusted odds ratios (ORs) and 95% confidence intervals (95%CIs) of receiving ET were estimated according to Charlson comorbidity, age, stage and subtype using logistic regression. The 2-year cumulative incidence and adjusted sub-hazard ratios (SHRs) of relapse were estimated using competing risk analysis, with all-cause death as the competing event. The z-test was used to assess differences in the proportion of patients receiving ET in 1996-1998 and 2009-2013.

Results: Ninety percent of the patients started adjuvant ET, range 96% (Belgium, Estonia, Slovenia, Spain)-75% (Switzerland). ORs of starting ET were lower for women aged > 75 years, with severe comorbidities, or luminal B HER2-positive cancer. The factors independently increasing the risk of relapse were: not receiving ET (SHR 2.26, 95%CI 1.02-5.03); severe comorbidity (SHR 1.94, 95%CI 1.06-3.55); luminal B, either HER2 negative (SHR 3.06, 95%CI 1.61-5.79) or positive (SHR 3.10, 95%CI 1.36-7.07); stage II (SHR 3.20, 95%CI 1.56-6.57) or stage III (SHR 7.41, 95%CI 3.48-15.73). ET use increased significantly but differently across countries from 51-85% in 1996-1998 to 86-96% in 2009-2013.

Conclusions: ER-positive BC patients in Europe are increasingly prescribed ET but between-country disparities persist. Older women and women with severe comorbidity less frequently receive ET. ET omission and severe comorbidity independently predict early disease relapse.

Keywords: Cancer registry; Comorbidity; Endocrine treatment; Oestrogen receptor-positive breast cancer; Relapse; Standard care.

MeSH terms

  • Adolescent
  • Adult
  • Age Factors*
  • Aged
  • Antineoplastic Agents, Hormonal / therapeutic use*
  • Breast Neoplasms / drug therapy*
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Comorbidity
  • Databases, Factual*
  • Estrogen Receptor alpha / metabolism*
  • Europe / epidemiology
  • Female
  • Humans
  • Incidence
  • Middle Aged
  • Neoplasm Recurrence, Local / epidemiology*
  • Neoplasm Recurrence, Local / metabolism
  • Neoplasm Recurrence, Local / pathology
  • Young Adult

Substances

  • Antineoplastic Agents, Hormonal
  • Estrogen Receptor alpha
  • estrogen receptor alpha, human