KEY POINTS
- The report describes a 37-year-old woman with ER-positive, PR-positive, HER2-negative invasive ductal breast carcinoma and extensive bilateral axillary and supraclavicular lymphadenopathy, much of which remained unexplained despite imaging, laboratory evaluation and multiple biopsies.
- Initial work-up showed a biopsy-proven primary tumor and ipsilateral axillary metastasis but negative contralateral axillary and bilateral supraclavicular sampling. Conventional staging therefore classified the disease as cT2N1M0, stage IIB, while the extensive persistent adenopathy remained diagnostically ambiguous.
- After four cycles of neoadjuvant docetaxel/cyclophosphamide, suspicious nodes remained. 18F-fluoroestradiol PET demonstrated intense estrogen-receptor-specific uptake in selected ipsilateral axillary, subpectoral and supraclavicular nodes while adjacent enlarged nodes—and enlarged contralateral nodes—showed no uptake.
- Based on the FES PET distribution, the patient was treated for presumed cT2N3, stage IIIC disease for radiation-planning purposes, despite the earlier negative supraclavicular fine-needle aspiration. This changed both the superior extent of the target and the dose strategy.
- The superior border of the supraclavicular radiation field was extended from the level of the cricoid to the inferior mandible. The patient received 40.05 Gy in 15 fractions to breast and regional nodes, followed by 12 Gy in six fractions to high level II/III and supraclavicular regions, with a simultaneous integrated boost to 15 Gy in six fractions for grossly FES-avid nodes.
- Subsequent mastectomy and axillary dissection showed substantial residual disease: a 7 × 5-cm tumor bed, 10 cm of DCIS, extensive lymphovascular invasion and 10 of 13 nodes positive, with extranodal extension, resulting in ypT3N3a pathology. This supports a high overall nodal disease burden but does not histologically validate every FES-avid supraclavicular node.
- FES PET has important limitations for planning: physiologic hepatic uptake limits evaluation of liver metastases, injection-site draining veins can retain tracer and mimic uptake, and this single case cannot determine diagnostic sensitivity, specificity or whether FES-guided field expansion improves local control.
CLINICAL TAKEAWAY
This case shows a plausible niche for FES PET in radiation oncology: ER-positive breast cancer with discordant biopsies and widespread indeterminate adenopathy where knowing which nodes actually express ER could change field design. It is not evidence for routine FES-guided contouring; prospective studies are needed before imaging alone is used to escalate nodal stage or dose.