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Poster Display session

68P - 20-year tamoxifen benefit in ER-positive/HER2-negative breast cancer patients in randomized clinical trials

Date

04 May 2022

Session

Poster Display session

Topics

Breast Cancer

Presenters

Huma Dar

Citation

Annals of Oncology (2022) 33 (suppl_3): S148-S164. 10.1016/annonc/annonc889

Authors

H.A. Dar1, A. Johansson2, A. Nordenskjöld3, C. Yau4, C. Benz5, L. Esserman6, K.A. Rodriguez-Wallberg7, B.A. Nordenskjöld3, G. Perez-Tenorio3, O. Stål8, T. Fornander9, L. Lindström10

Author affiliations

  • 1 Karolinska Institute, Stockholm/SE
  • 2 Karolinska Institutet, Huddinge/SE
  • 3 LiU - Linköping University, Linköping/SE
  • 4 UCSF - University of California San Francisco, San Francisco/US
  • 5 Buck Institute for Age Research, Novato/US
  • 6 UCSF Helen Diller Family Comprehensive Cancer Center, San Francisco/US
  • 7 Karolinska Universitetssjukhuset Huddinge - Reproduktionsmedicin, Huddinge/SE
  • 8 Linköping University Hospital, Linkoping/SE
  • 9 Karolinska Institutet, 171 77 - Huddinge/SE
  • 10 Karolinska Institutet, Stockholm/SE
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Abstract 68P

Background

The clinically used breast cancer markers are known to predict short-term survival, but whether they predict long-term survival is unclear. We therefore aimed to investigate the long-term benefit from tamoxifen (TAM) by clinically used markers in ER-positive/HER2-negative breast cancer patients.

Methods

Secondary analysis of ER-positive/HER2-negative patients (n=1242) in the Stockholm tamoxifen trials (1976-1996) randomized to TAM (40 mg) vs no TAM. Complete 20-year follow-up was from Swedish registers. Distant recurrence-free interval (DRFI) by clinically used markers was assessed by Kaplan-Meier, multivariable Cox proportional hazards, and time-varying analysis.

Results

Kaplan-Meier analysis showed significantly (log-rank P<0.05) improved long-term DRFI from TAM vs no TAM for larger tumor size (T1c P<0.001; T2-3 P=0.012), grade 2 (P<0.001), lymph node-negative (P<0.001), PR-positive (P<0.001) and Ki-67-low tumors (P<0.001). Multivariable analysis (Table) showed significant long-term TAM benefit for patients with larger tumor size (T1c HR=0.56; 95% CI, 0.42-0.75; T2 HR=0.67; 95% CI, 0.49-0.92), grade 2 (HR=0.55; 95% CI, 0.42-0.71), lymph node-negative (HR=0.45, 95% CI, 0.33-0.62), PR-positive (HR=0.59, 95% CI, 0.47-0.75) and Ki-67-low tumors (HR=0.55, 95% CI, 0.43-0.71). Time-varying analysis showed that patients with tumor size T1c, grade 2, lymph node-negative, PR-positive, and Ki-67-low tumors significantly benefitted from TAM for 20 years (HR=0.56, 95% CI: 0.35-0.92; HR=0.49, 95% CI: 0.32-0.76; HR=0.50, 95% CI: 0.30-0.84; HR=0.54, 95% CI: 0.36-0.80; HR =0.51, 95% CI: 0.34-0.75 at year 20, respectively). Patients with tumor size T2-3 had significant TAM benefit for 10 years (HR=0.62, 95% CI: 0.40-0.96 at year 10). Table: 68P

Clinically used variables Category Trial arm Risk of distant recurrence HR (95% CI)
Tumor size T1a/b TAM+ 0.81 (0.39-1.68)
TAM- 1.0 ref.
T1c TAM+ 0.56 (0.42-0.75)
TAM- 1.0 ref.
T2-3 TAM+ 0.67 (0.49-0.92)
TAM- 1.0 ref.
Tumor grade Grade 1 TAM+ 0.85 (0.43-1.71)
TAM- 1.0 ref.
Grade 2 TAM+ 0.55 (0.42-0.71)
TAM- 1.0 ref.
Grade 3 TAM+ 0.91 (0.61-1.38)
TAM- 1.0 ref.
Lymph node status Negative TAM+ 0.45 (0.33-0.62)
TAM- 1.0 ref.
Positive TAM+ 0.85 (0.64-1.11)
TAM- 1.0 ref.
PR status Positive TAM+ 0.59 (0.47-0.75)
TAM- 1.0 ref.
Negative TAM+ 0.68 (0.45-1.03)
TAM- 1.0 ref.
Ki-67 status Low TAM+ 0.55 (0.43-0.71)
TAM- 1.0 ref.
Medium/High TAM+ 0.72 (0.49-1.06)
TAM- 1.0 ref.

Conclusions

Our findings suggest a significant long-term tamoxifen treatment benefit among patients with larger tumors, lymph node-negative tumors, PR-positive tumors, and Ki-67 low tumors.

Clinical trial identification

The trial center for the STO-trials was the Regional Cancer Center Stockholm-Gotland, in Stockholm Sweden. However, the start of the Stockholm Tamoxifen trials in 1976 was well before trial registration started in Sweden, therefore information on trial number is not available.

Legal entity responsible for the study

The authors.

Funding

Swedish Research Council, Swedish Research Council for Health, Working life and Welfare, The Gösta Milton Donation Fund and Swedish Cancer Society.

Disclosure

All authors have declared no conflicts of interest.

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