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PERSEPHONE

Six months of trastuzumab was almost as good as twelve, with half the heart toxicity, though twelve remains the global standard.

4-year DFS 89.4% vs 89.8% (HR 1.07), meeting non-inferiority; cardiac events requiring discontinuation 4% vs 8%. Other shorter-duration trials (PHARE, SOLD, Short-HER) were inconclusive, so most guidelines retain 12 months while accepting 6 in resource-limited settings.

Setting
Adjuvant HER2+ early breast cancer: 6 vs 12 months of trastuzumab
Phase
Phase 3
Sponsor
Cancer Research UK
Registry
Headline result
4-year DFS 89.4% vs 89.8%, non-inferior.
Reported
2019
Enrolled
4088
Replication
PHARE, SOLD, Short-HER did not establish non-inferiority; pooled analyses suggest a small loss with shorter therapy in higher-risk disease.

Outcomes

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In plain words
What these results mean for people, not percentages
4,088 people took part
4-year disease-free survivalprimarysurrogate endpoint
  • 89.4 vs 89.8 out of 100 alive without the cancer coming back at 4 years with 6 months trastuzumab compared with 12 months trastuzumab; 0.4 fewer per 100.
  • On this measure the first group did worse, not better.
  • Put another way, the treated group had about 7 percent higher chance of the event at any given time (hazard ratio 1.07, likely range 0.93 to 1.24).
  • The likely range for the hazard ratio crosses 1, so the difference could be due to chance.
  • This is a surrogate endpoint: it measures the cancer being controlled or absent on scans and tests, which often, but not always, translates into living longer.
  • These results apply to the people the trial enrolled: Adjuvant HER2+ early breast cancer: 6 vs 12 months of trastuzumab. People in a different situation may not see the same effect.
  • The trial selected people by a biomarker (HER2); the result should not be assumed for people whose cancer does not have it.

Numbers are from the trial as recorded here; see the source links in the table below. This is orientation, not medical advice: ask your team how closely the trial population matches you.

4,088 participants enrolled.

4-year disease-free survivalprimary
HR 1.07 (0.93–1.24)
6 months trastuzumab89.4 of 100
n = 2,043
12 months trastuzumab89.8 of 100
n = 2,045
Source
EndpointArmnValueHR (95% CI)pSource
4-year disease-free survivalprimary6 months trastuzumab2,04389.4%1.07 (0.93–1.24)link
12 months trastuzumab2,04589.8%
Replication
PHARE, SOLD, Short-HER did not establish non-inferiority; pooled analyses suggest a small loss with shorter therapy in higher-risk disease.

Connected

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