The Japan Breast Cancer Research Group (JBCRG) released 71-month follow-up results from the POSITIVE trial in Annals of Oncology, demonstrating that chemotherapy provides no significant benefit in disease-free survival for patients with HR+, HER2- early breast cancer who possess low-risk genomic scores despite having other clinical risk factors.
Genomic Scores vs. Clinical Risk Factors in the POSITIVE Trial
The POSITIVE trial, officially designated as JBCRG-01002, addressed a specific clinical tension in breast cancer treatment: the conflict between clinical risk factors and genomic assay results. In standard practice, clinicians often rely on tumor size, lymph node involvement, and grade to determine if chemotherapy is necessary. However, genomic assays like Oncotype DX provide a recurrence score (RS) that predicts the actual likelihood of benefit from chemotherapy.
The trial enrolled patients with hormone receptor-positive (HR+), HER2-negative early breast cancer who were clinically categorized as high-risk but had low-risk genomic scores. This created a cohort where traditional guidelines suggested chemotherapy, but the molecular profile suggested it might be unnecessary. By comparing endocrine therapy (ET) alone against a combination of chemotherapy and ET, the JBCRG sought to determine if the genomic score is a more reliable predictor of outcome than clinical staging.
The study design specifically targeted the "grey zone" of treatment decision-making. For these patients, the risk of chemotherapy-induced toxicity—including neuropathy and secondary malignancies—must be weighed against the potential for reduced recurrence. The 71-month analysis provides the long-term evidence needed to justify omitting chemotherapy in this specific subgroup.
71-Month Disease-Free Survival and Recurrence Rates
The long-term data published in Annals of Oncology indicates that adding chemotherapy did not result in a statistically significant improvement in disease-free survival (DFS). The 71-month follow-up confirms that the trend observed in earlier interim analyses remained stable over time.
Patients receiving endocrine therapy alone showed recurrence rates comparable to those who received both chemotherapy and endocrine therapy. This suggests that for patients with a low genomic recurrence score, the biological drivers of the tumor are less likely to respond to cytotoxic chemotherapy, regardless of the clinical stage or node status that would typically trigger its use.
The lack of a significant difference in DFS implies that the biological signature of the tumor, as captured by the genomic assay, outweighs the prognostic value of traditional clinical markers in this population. While clinical factors identify who is more likely to recur, the genomic score identifies who is more likely to benefit from the addition of chemotherapy. In the POSITIVE trial, the low-risk genomic score correctly identified a group that could safely forgo chemotherapy without compromising their long-term survival prospects.
Reducing Treatment Toxicity in Low-Risk Patients
The clinical implication of the POSITIVE trial results is a shift toward more personalized, "de-escalated" therapy. Chemotherapy is associated with significant morbidity. By validating that endocrine therapy alone is sufficient for genomically low-risk patients, the JBCRG provides a framework to reduce the treatment burden on thousands of patients.
This shift is particularly relevant for older patients or those with comorbidities who are more susceptible to the adverse effects of chemotherapy. The trial demonstrates that the avoidance of chemotherapy does not come at the cost of increased recurrence for this specific genomic profile.
The findings align with a broader movement in oncology toward molecularly driven treatment. Rather than treating a "stage" of cancer, clinicians are increasingly treating the "biology" of the tumor. The POSITIVE trial adds a critical layer of evidence to this approach by showing that the benefit of chemotherapy is absent even when clinical markers suggest high risk, provided the genomic score remains low.
Future Application of Genomic Profiling
While the POSITIVE trial provides clarity for HR+, HER2- patients, the results emphasize the necessity of genomic testing as a standard component of the diagnostic workup. Without a genomic assay, clinicians would likely continue to administer chemotherapy to these patients based on their clinical risk factors, exposing them to unnecessary toxicity.
The JBCRG’s findings suggest that the recurrence score should be the primary driver for chemotherapy decisions in early-stage HR+ breast cancer. However, the study also highlights the need for continued monitoring. While DFS was not significantly improved, the trial continues to inform how clinicians manage the long-term endocrine therapy required for these patients.
Future research will likely focus on whether specific subtypes of "low-risk" genomic tumors still benefit from chemotherapy or if other targeted therapies can replace the role of cytotoxic drugs entirely. For now, the 71-month data serves as a benchmark for avoiding over-treatment in breast cancer care.
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