Tailoring local therapy in breast cancer

By Agata Buczak

​​Imaging‑informed strategies are helping refine escalation and de‑escalation of local therapy in breast cancer​

How can imaging and local therapy be optimized to avoid overtreatment while maintaining oncologic outcomes in breast cancer? In collaboration with the Bulgarian Joint Cancer Network (BJCN), insights from the San Antonio Breast Cancer Symposium (SABCS) 2025, presented at the licensed Best of SABCS^® meeting in Bulgaria provided new evidence to help refine escalation and de‑escalation decisions across diagnostic imaging, axillary management, and radiotherapy techniques.

When should preoperative breast MRI guide escalation of postoperative radiotherapy for residual IMC nodal disease after neoadjuvant therapy?

In patients with residual internal mammary chain (IMC) nodal involvement following neoadjuvant systemic therapy, preoperative breast MRI may help identify those who benefit from radiotherapy escalation.¹ Y. Peng et al. presented data showing that confirmation of residual IMC disease on MRI was associated with a significant improvement in distant recurrence‑free survival when high‑dose postoperative radiotherapy to the IMC was delivered.¹

By contrast, in patients with initial IMC nodal involvement (cN3) who achieved a complete radiologic response (ycN0) after neoadjuvant therapy, no benefit of postoperative IMC radiotherapy was observed for local or distant recurrence‑free survival.¹

Should routine preoperative breast MRI be added before breast‑conserving surgery in early TNBC or non‑luminal HER2‑positive disease?

Isabelle Bedrosian et al. presented findings on the value of routine preoperative breast MRI evaluated in the Alliance A011104/ACRIN 6694 trial.² Among patients with early triple‑negative or non‑luminal human epidermal growth factor receptor 2 (HER2)‑positive breast cancer without pathogenic germline BRCA1/2 mutations and planned breast‑conserving surgery, adding MRI to conventional staging did not significantly reduce locoregional recurrence.²

How can serial FDG PET–CT be used to assess treatment response in metastatic bone disease from luminal breast cancer?

The FEATURE trial (ECOG‑ACRIN EA1183), presented by Jennifer Specht et al., examined serial FDG PET–CT in metastatic bone disease from luminal breast cancer.³ Categorization of response using modified PERCIST (mPERCIST) criteria correlated with progression‑free survival, despite notable inter‑observer variability. FDG PET–CT may therefore complement standard clinical and radiologic assessment when evaluating response to systemic therapy.³

When should radiotherapy be intensified or de‑escalated?

In non–low‑risk ductal carcinoma in situ (DCIS), findings from the BIG 3‑07/TROG 07.01 trial, presented by Boon H. Chua et al., showed that adding a tumor bed boost after breast‑conserving surgery reduced local recurrence, regardless of fractionation, but increased rates of grade ≥2 breast pain and fibrosis.⁴

Radiotherapy de‑escalation was addressed in the INSEMA trial, presented by Guido Hildebrandt et al., where omission of postoperative radiotherapy in selected low‑risk early breast cancer did not significantly affect invasive disease‑free survival, but was associated with a higher risk of local recurrence.⁵ 

Key takeaways

• Preoperative imaging, particularly MRI, can help identify patients who may benefit from escalation or de‑escalation of local therapy after neoadjuvant treatment
• Routine use of advanced imaging is not universally beneficial and should be tailored to disease subtype and treatment intent
• Functional imaging with FDG PET–CT may complement conventional methods for response assessment in metastatic bone disease
• Radiotherapy intensification can improve local control in higher‑risk settings but is associated with increased toxicity
• Carefully selected patients with early breast cancer may be candidates for radiotherapy de‑escalation, which emphasizes the need for individualized treatment decisions

Read more about consensus and new recommendations from Best of 2025 SABCS^® Bulgaria. 

References

1. Peng, 2026. Abstract RF1-03: Magnetic resonance imaging based internal mammary node response after neoadjuvant therapy to guide postoperative internal mammary node boost radiotherapy in breast cancer. https://www.doi.org/10.1158/1557-3265.Sabcs25-rf1-03
2. Bedrosian, 2026. Abstract GS2-07: Effect of preoperative breast MRI staging on local regional recurrence (LRR) in early stage breast cancer: Alliance A011104/ACRIN 6694. https://www.doi.org/10.1158/1557-3265.Sabcs25-gs2-07
3. Specht, 2026. Abstract RF4-06: FDG-PET to assess therapeutic response in patients with bone-dominant metastatic breast cancer, FEATURE: ECOG-ACRIN EA1183. https://www.doi.org/10.1158/1557-3265.Sabcs25-rf4-06
4. Chua, 2022. Radiation doses and fractionation schedules in non-low-risk ductal carcinoma in situ in the breast (BIG 3–07/TROG 07.01): A randomised, factorial, multicentre, open-label, phase 3 study. https://www.doi.org/10.1016/S0140-6736(22)01246-6
5. Reimer, 2025. Axillary surgery in breast cancer — Primary results of the INSEMA trial. https://www.doi.org/10.1056/NEJMoa2412063

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