Elsevier

Annals of Oncology

Volume 32, Issue 11, November 2021, Pages 1410-1424
Annals of Oncology

Original Article
Outcome of breast cancer patients with low hormone receptor positivity: analysis of a 15-year population-based cohort

https://doi.org/10.1016/j.annonc.2021.08.1988Get rights and content
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open access

Highlights

  • This study compared HR low positive tumors with HR-negative and HR strongly positive tumors, respectively.

  • In the HER2-negative cohort outcome of HR low positive tumors was similar to that of HR-negative tumors.

  • In the HER2-positive cohort no statistically significant differences were observed.

  • Current definitions for HR positivity and its clinical relevance should be reconsidered.

  • Patients with HR low pos./HER2-neg. tumors could be regarded and treated similar to patients with triple-negative tumors.

Background

Guideline recommendations for the treatment of breast cancer with low hormone receptor (HR) expression (1%-9%) are ambiguous and several studies showed more similarities with HR-negative tumors than with HR strongly positive tumors (≥10%). We used a population-based 15-year cohort to compare patient characteristics and outcome of HR low positive tumors with HR-negative and HR strongly positive tumors, respectively.

Patients and methods

A total of 38  560 women diagnosed with early invasive breast cancer between 2004 and 2018 within the scope of the Munich Cancer Registry with 4.9 million inhabitants were included. Descriptive analyses of prognostic factors, treatment, and outcome analyses using the Kaplan–Meier method; cumulative incidence in consideration of competing risks; and multivariate analyses (Cox regression and Fine–Gray model) were conducted. Endpoints were time to local recurrence (TTLR), time to lymph node recurrence (TTLNR), time to metastasis (TTM), overall survival (OS), and relative survival (RS).

Results

A total of 861 patients (2%) had HR low positive, 4862 (13%) HR-negative, and 32  837 (85%) HR strongly positive tumors. Within the HER2-negative cohort (n = 33  366), survival of HR low positive tumors was significantly worse than that of HR strongly positive tumors [OS hazard ratio 0.66 (95% confidence interval 0.55-0.78)], whereas between HR low positive and HR-negative tumors no significant survival difference could be detected [OS hazard ratio 0.93 (95% confidence interval 0.78-1.11)]. TTLR, TTLNR, and TTM showed similar results. By contrast, within the HER2-positive cohort (n = 5194), no statistically significant differences between the three HR groups could be detected in multivariate analyses.

Conclusion

Current definitions for HR positivity and its clinical relevance should be reconsidered. Patients with HR low positive/HER2-negative tumors could be regarded and treated similar to patients with triple-negative tumors.

Key words

breast cancer
cancer registry
hormone receptor
systemic therapy
health services research

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