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Poster display - Cocktail

734 - Hormonal therapy confers clinically relevant benefit in women with low estrogen receptor-positive breast tumor

Date

24 Nov 2018

Session

Poster display - Cocktail

Presenters

Tianjiao Zhang

Citation

Annals of Oncology (2018) 29 (suppl_9): ix8-ix12. 10.1093/annonc/mdy427

Authors

T. Zhang1, B. Ho2, P.M.Y. Chan3, E.Y. Tan3

Author affiliations

  • 1 Yong Loo Lin School Of Medicine, National University of Singapore, 119228 - Singapore/SG
  • 2 Department Of Pathology, Tan Tock Seng Hospital, 308433 - Singapore/SG
  • 3 Department Of General Surgery, Tan Tock Seng Hospital, 308433 - Singapore/SG
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Resources

Abstract 734

Background

Breast tumours expressing low levels of estrogen receptor (ER) were considered ER negative and not generally recommended hormonal therapy until the change in guidelines in 2010. This study aims to examine the profile of women with low-ER tumours and determine the effect of hormonal therapy on disease outcomes. We also aim to identify those at high risk of recurrence.

Methods

A total of 2872 women with breast cancer from Tan Tock Seng Hospital were recruited and studied between 2001 and 2012. Low ER-positive tumours are defined as tumours with 1% to 9% positively stained cells. Associations of low ER expression with clinicopathological parameters and distant recurrence were examined with univariate and multivariate analyses. Disease-free and overall survivals were examined using Kaplan-Meier curves.

Results

2037 of 2872 women had ER-positive tumours at diagnosis. Of the 171 women with low-ER positive tumours, 120 (70.2%) received hormonal therapy. Low ER expression occurred more frequently in younger women (P < 0.001), in Malay or Indian ethnicity (P = 0.002) and were associated with high tumour grade (P = 0.003 and P < 0.001 for DCIS and invasive cancers respectively), absent PR expression (P < 0.001) and HER2-overexpression (P < 0.001). Distant disease-free survival of women with low ER-positive tumors was shorter than that of those with high ER-positive tumors (P = 0.005), but was similar to that of those with ER-negative tumors (P = 0.574). Distant recurrence was significantly more common in women with low ER-positive cancers than high ER-positive cancers (P = 0.029). Advanced stage III disease (P = 0.002) and hormonal therapy (P < 0.001) were associated with distant recurrence in women with low ER-positive cancers. Hormonal therapy significantly reduced the likelihood of distant recurrence (P < 0.001) and of mortality in women with low ER-positive invasive cancers (P = 0.011).

Conclusions

Hormonal therapy reduced distant recurrence and conferred overall survival advantage in women with low ER-positive tumors. Hence hormonal therapy should be recommended to them, particularly those with advanced disease and absent PR expression, who are at high risk of distant recurrence.

Editorial acknowledgement

Clinical trial identification

Legal entity responsible for the study

National Healthcare Group Singapore.

Funding

National Healthcare Group Singapore.

Disclosure

All authors have declared no conflicts of interest.

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