A recent analysis by the Early Breast Cancer Trialists’ Collaborative Group (EBCTCG), published in The Lancet, reveals a significant decline in the risk of distant recurrence among women with early breast cancer enrolled in clinical trials between 1990 and 2009. The study, encompassing data from over 155,000 women, highlights the impact of improved treatments and patient characteristics on long-term outcomes.
Study Details and Key Findings
The pooled analysis included data from 151 trials, comparing distant recurrence rates in patients enrolled from 1990 to 1999 with those enrolled from 2000 to 2009. The findings indicate a notable reduction in the 10-year distant recurrence risk across various subgroups.
In node-negative patients, the 10-year distant recurrence risk decreased from 10.1% to 3% in estrogen receptor (ER)-positive disease and from 18.3% to 11.9% in ER-negative disease. Among patients with one to three positive nodes, the risk decreased from 19.9% to 14.7% in ER-positive disease and from 31.9% to 22.1% in ER-negative disease. For those with four to nine positive nodes, the risk decreased from 39.6% to 28.5% in ER-positive disease and from 47.8% to 36.5% in ER-negative disease.
Impact of Improved Treatments and Patient Characteristics
Analysis suggests that 80.5% of the improvement in distant metastasis risk for ER-positive disease and 89.8% for ER-negative disease could be attributed to changes in patient and tumor characteristics, as well as advancements in treatments. These included a higher proportion of patients with node-negative disease in more recent trials. Even after adjustment for these factors, the improvements remained statistically significant (P < .0001).
After adjusting for therapy, rates of distant recurrence were reduced by 25% among patients with ER-positive disease and 19% among those with ER-negative disease over the two time periods.
Implications for Long-Term Management
The investigators concluded that a significant portion of the improvement in trial outcomes is due to a greater proportion of women with lower-risk disease entering trials and improved adjuvant treatment. They also noted that after adjustment, women diagnosed since 2000 have approximately a fifth lower rate of distant recurrence than those from the 1990s. While long-term risks of distant recurrence for estrogen receptor-positive disease persist, they are about a tenth lower than previously reported.
