medwireNews: The risk for breast cancer recurrence increases at a steady rate for at least 15 years after the end of planned endocrine therapy and is strongly associated with the original tumor diameter and nodal (TN) status, meta-analysis data show.
The findings are based on the results of 88 trials involving 62,923 women with early-stage estrogen receptor (ER)-positive breast cancer who were disease-free after 5 years of scheduled endocrine therapy.
Hongchao Pan (University of Oxford, UK) and co-investigators from the Early Breast Cancer Trialists’ Collaborative Group say the results have “implications for long-term follow-up strategies and [highlight] the need for new approaches to reduce late recurrence.”
“The risk could be somewhat reduced by extending the duration of endocrine therapy, with greater absolute benefits for those at highest risk for recurrence,” they add.
The researchers report in The New England Journal of Medicine that patients with stage T1 disease and no nodal involvement (T1N0) had a 13% cumulative risk for distant recurrence at 20 years. This increased to 20% with one to three nodes involved (T1N1–3), and 34% with four to nine nodes involved (T1N4–9).
The corresponding risks among women initially diagnosed with stage T2 disease were 19% with T2N0, 26% with T2N1–3, and 41% with T2N4–9.
Similar results were observed for the risk for death from breast cancer, but there was no association between TN status and the risk for contralateral breast cancer, the researchers remark.
The team also found that tumor grade and the presence of Ki-67 antibody (which were strongly correlated with each other) only moderately predicted long-term outcome, despite being important independent prognostic factors during the first 5 years.
Progesterone receptor and human epidermal growth factor receptor type 2 receptor status also predicted outcome during the first 5 years, but had no impact on long-term prognosis.
When Pan et al further divided the patients according to tumor grade, they found that, among patients with T1N0 breast cancer, the absolute risk for distant recurrence during years 5 to 20 was 10% for low-grade disease, 13% for moderate-grade disease, and 17% for high-grade disease.
The corresponding risks for any recurrence or a contralateral breast cancer were 17%, 22%, and 26%, respectively.
The study authors conclude: “Recognition of the magnitude of the long-term risks of ER-positive disease can help women and their health care professionals decide whether to extend therapy beyond 5 years and whether to persist if adverse events occur.”
By Laura Cowen
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