S288
Clinical - Breast
ESTRO 2026
controversy remains regarding the use of IMNI in certain subgroups. Therefore, the present study aimed to perform a patient-level meta-analysis of the DBCG IMN1 and IMN2 studies, allowing subgroup analysis of clinical relevance. Material/Methods: The DBCG IMN1 and IMN2 were prospective, nationwide, population-based cohort studies. Node- positive breast cancer patients with right-sided tumours were allocated to IMNI, whereas patients with left-sided tumours were allocated to no IMNI [3,4]. All patients had axillary lymph node dissection and received locoregional radiotherapy (RT). The DBCG IMN1 (2003-07) and IMN2 (2007-14) studies were combined to perform a patient-level meta-analysis. Crude and adjusted hazard ratios (HR) were calculated using the Cox proportional hazard model. Applying competing events, cumulative incidences were calculated for DM and BCM, while the Kaplan-Meier method was used for OS. Results: In total, 7630 patients treated 2003-14 were analysed. Median age was 58 years, mastectomy was performed in 54% of patients, and 64.5% had 1-3 positive axillary nodes. Baseline characteristics were evenly distributed between patients treated with IMNI and without IMNI (data not shown). The median follow-up was 14.1 years for OS. OS was improved in patients treated with IMNI compared to no IMNI with a crude HR of 0.86 (95% CI 0.80-0.93, p<0.0001) and an adjusted HR of 0.85 (95% CI 0.79-0.92, p<0.0001). For BCM and DM, similar significant effects were seen, Figure 1. Subgroup analysis showed that the effect of IMNI was maintained in patients with only 1 macrometastatic lymph node (HR 0.83, 95% CI 0.71- 0.96). A higher efficacy of IMNI was seen in patients treated with both chemotherapy and endocrine therapy compared to either one or none. Age, tumour size, tumour location, and type of surgery did not affect the efficacy of IMNI, Figure 2. The 15-year cumulative incidence of cardiovascular death was 0.6% in patients with right-sided tumours and 1.1% in left- sided.
need for new strategies to determine the long term prognosis of these patients. We selected a group of patients to analyze the presence of CAF S1 fibroblast for a future study. Distant recurrence in T1N0 Luminal BC is strongly associated with the presence of CAF-S1 fibroblast The determination of CAF-S1 could more accurately predict recurrence in this subgroup of patients and could be a target for future treatments References: -Parker, J. S., Mullins, M., Cheang, M. C., Leung, S., Voduc, D., Vickery, T., ... & Bernard, P. S. (2009). Supervised risk predictor of breast cancer based on intrinsic subtypes. Journal of clinical oncology, 27(8), 1160-1167-Meattini I, Coles CE, Tramm T, Borghesi S, Krug D, Montero A, Nardone V, Salvestrini V, Valzano M, Valentini V, Aristei C. Biomarker-Directed Radiotherapy in Breast Cancer: A Narrative Review. JAMA Oncol. 2025 Mar 1;11(3):329-339. doi: 10.1001/jamaoncol.2024.5780. PMID: 39820307- Bonneau, C., Eliès, A., Kieffer, Y., Bourachot, B., Ladoire, S., Pelon, F. (2020). A subset of activated fibroblasts is associated with distant relapse in early luminal breast cancer. Breast Cancer Research, 22, 1- 22 Keywords: BREAST , LUMINAL CANCER, EARLY STAGES Internal mammary node irradiation in 7630 node- positive breast cancer patients: A patient-level meta-analysis of the DBCG IMN1 and IMN2 studies Anders W. Mølby Nielsen 1,2 , Lise B. J. Thorsen 1,2 , Demet Özcan 2,3 , Louise W. Matthiessen 4 , Else Maae 5 , Marie L. H. Milo 6 , Mette H. Nielsen 7 , Trine Tramm 3 , Jens Overgaard 2 , Birgitte V. Offersen 1,2 1 Department of Oncology, Aarhus University Hospital, Aarhus, Denmark. 2 Department of Experimental Clinical Oncology, Aarhus University Hospital, Aarhus, Denmark. 3 Department of Pathology, Aarhus University Hospital, Aarhus, Denmark. 4 Department of Oncology, Copenhagen University Hospital Herlev and Gentofte, Copenhagen, Denmark. 5 Department of Oncology, Vejle Hospital, University Hospital of Southern Denmark, Vejle, Denmark. 6 Department of Oncology, Aalborg University Hospital, Aalborg, Denmark. 7 Department of Oncology, Odense University Hospital, Odense, Denmark Purpose/Objective: The Danish Breast Cancer Group (DBCG) internal mammary node (IMN) 1 and 2 studies showed that internal mammary node irradiation (IMNI) reduced distant metastasis (DM), lowered breast cancer mortality (BCM), and improved overall survival (OS) in node-positive breast cancer patients [1,2]. However, these studies were analysed separately, and Proffered Paper 2803
Made with FlippingBook - Share PDF online