As in previous years, this year’s American Society of Clinical Oncology (ASCO) Congress, held in Chicago, featured important developments in the field of breast cancer. The overall message of ASCO 2026 was very clear: more personalization, less unnecessary treatment, and higher quality of life. Treatment decisions are now shaped not only by tumor size or stage, but also by biological characteristics and the patient’s individual risk profile.
The Era of Changing Treatment Earlier with Liquid Biopsy
One of the most notable studies of the congress was the SERENA-6 study. This research evaluated the benefit of changing treatment when ESR1 mutations emerging in circulating tumor DNA (ctDNA) were detected in metastatic hormone receptor-positive/HER2-negative breast cancer before progression was seen with imaging methods. The results showed that identifying resistance at the molecular level in the early period may extend the duration of disease control.
This study suggests that liquid biopsy may become part of routine practice in breast cancer follow-up in the near future. Perhaps in the coming years, instead of waiting only for radiological progression, treatments will be changed earlier by monitoring molecular changes.
A New Standard on the Horizon in HER2-Positive Disease
Another important topic at ASCO 2026 was HER2-positive metastatic breast cancer. In the DESTINY-Breast09 study, the data obtained with the combination of trastuzumab deruxtecan (T-DXd) and pertuzumab showed stronger efficacy compared with long-standing standard first-line treatments.
These results indicate that antibody-drug conjugates (ADCs) will begin to be used not only in later lines of treatment, but also in earlier stages of therapy. ADC technology, one of the most important transformations in breast cancer treatment in recent years, appears likely to take on an even more central role in the coming period.
Combination Treatments Are Gaining Strength in Triple-Negative Breast Cancer
Triple-negative breast cancer is still considered one of the most aggressive subtypes of breast cancer. Studies presented at ASCO 2026 showed that the combined use of immunotherapy and antibody-drug conjugates produced promising results. In particular, combinations of sacituzumab govitecan and immunotherapy were reported to potentially increase treatment success in certain patient groups.
These developments show that treatment options, which have long been limited in triple-negative breast cancer, are gradually expanding.
A Less Extensive, Smarter Approach in Surgery
From the perspective of a breast surgeon, one of the most important messages of ASCO 2026 was related to axillary surgery. The updated results of the SENOMAC study showed that safe outcomes can be achieved in many patients with limited sentinel lymph node involvement without performing axillary dissection. In addition, this approach significantly reduces complications that negatively affect quality of life, such as lymphedema and restricted shoulder movement.
These findings reveal that the long-standing de-escalation process in breast cancer surgery is continuing to gain strength. The goal is no longer only to treat cancer, but also to preserve the patient’s arm function, quality of life, and daily activities.
Genomic Tests Are Changing Chemotherapy Decisions
At ASCO 2026, the importance of genomic testing was once again emphasized. The data presented showed that chemotherapy can be safely avoided in some early-stage breast cancer patients with high clinical risk through genomic analyses.
This development is an important example showing that tumor biology has become more decisive than anatomical features in breast cancer treatment. Today, it is much more clearly understood why two patients at the same stage may receive completely different treatments.
Conclusion
Following ASCO 2026, it is possible to summarize the three key concepts that stood out in the breast cancer field as follows:
First, treatments are becoming increasingly personalized.
Second, strong evidence is increasing for reducing unnecessary surgery and unnecessary chemotherapy.
Third, thanks to liquid biopsy, genomic testing, and next-generation targeted treatments, the disease can be managed earlier and with greater precision.
The future of breast cancer treatment is not based on a more aggressive approach, but on a smarter, more selective, and more personalized one. This was exactly the most important message of ASCO 2026.
