medwireNews: Long-term results from the ShortHER trial of adjuvant trastuzumab de-escalation provide reassurance for patients with HER2-positive, early breast cancer who may need to discontinue treatment before completing the standard 1-year course.
At a median follow-up of 8.7 years, the long-term disease-free survival (DFS) and overall survival (OS) curves for the 9-week and 1-year courses of trastuzumab were “superimposable” among the 85% of the study population with low- or intermediate-risk disease, presenter Pier Franco Conte (University of Padova, Italy) told delegates of the ESMO Breast Cancer Virtual Congress 2021.
He stressed, however, that as the trial was previously unable to demonstrate the noninferiority of the 9-week course, the 1-year regimen remains the standard of care, but based on the updated results Conte believes that “de-escalated treatments are a reasonable option for a large proportion of real-world HER2-positive, early breast cancer patients.”
Evandro de Azambuja (Institut Jules Bordet, Brussels, Belgium), who discussed the presentation, agreed that 1-year trastuzumab remains the standard, but added that “a shorter trastuzumab administration could be an option to be tested in patients with a low risk of relapse or to reassure patients who experience cardiac events before the end of therapy.”
The discussant continued: “This regimen could facilitate the access to trastuzumab [in] patients with low risk of relapse living in countries with limited resources.”
The trial included 1253 patients with HER2-positive, node-positive or high-risk node-negative disease who were randomly assigned to receive sequential anthracycline–taxane combinations alongside either 9 weeks or 1 year of trastuzumab.
A total of 37.5% of participants were considered to be at low risk of relapse on the basis of tumor size and nodal status (pT≤2 cm, N0), while 47.1% had an intermediate risk (pT≤2 cm, N1–N3 or pT>2 cm, N0–N3) and 15.4% had a high risk (any pT, N4+).
Overall, the 5-year DFS rate in the current analysis was 85.8% in the 9-week trastuzumab arm and 87.9% in the 1-year arm; the 5-year OS rate was identical in both groups, at 95.1%.
When stratified by risk category, the 5-year DFS rates remained comparable between the 9-week and 1-year groups for patients with low or intermediate risk, at 91% versus 91% and 89% versus 88%, respectively. By contrast, the rates were lower in the 9-week than 1-year group for high-risk patients, at 64% versus 82% and a hazard ratio of 2.06.
The OS findings were similar in the three risk groups, reported Conte, such that the 5-year rates with 9 weeks versus a year of trastuzumab were 99% versus 97% among low-risk patients, 95% versus 96% among intermediate-risk patients, and 91% versus 95% among those at high risk.
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