New in Advances in Radiation Oncology: FES-PET for staging newly diagnosed invasive lobular carcinoma Key finding: In a 4-patient case series, FES-PET changed or supported management in all 3 patients who received it. Case 1: occult supraclavicular nodal (SUVmax 3.3) and chest wall avidity (SUVmax 5.4) after NAC and three margin-positive surgeries prompted a 1000 cGy in 5 fraction sequential boost. Case 2: biopsy-confirmed osseous metastases shifted a cT3N3bM0 patient from curative intent to first-line metastatic therapy. Case 3: a negative scan supported proceeding with chest wall RT and RNI. A fourth patient staged with conventional imaging alone went from cT2N1M0 to pT3N3a at surgery. Why it matters: ILC is a known blind spot for mammography, MRI, and FDG-PET. When occult nodal disease shows up before the plan is locked, it changes volumes, dose, and sometimes intent. Important caveat: n = 4, retrospective, selection bias in who got scanned, no systematic comparison with conventional imaging, and short follow-up. The SCL node in case 1 was treated based on tracer avidity without pathologic confirmation. FES-PET is NCCN-supported for recurrent or metastatic ILC, not for primary staging. Bottom line: This is a signal, not a standard. Useful hypothesis-generating data for a real staging gap, but prospective work is needed before upfront FES-PET changes how we stage locally advanced ILC. doi.org/10.1016/j.adro.2026.… @ASTRO_org #RadOnc #OncTwitter #BCSM