18F-FDG-PET/CT for systemic staging of patients with newly diagnosed ER-positive and HER2-positive breast cancer.

18F-FDG-PET/CT revealed distant metastases in 14% (95% CI: 9-20%) of patients with stage IIB ER+/HER2- and HER2+ breast cancer, which is similar to upstaging rates previously seen in patients with stage IIB triple-negative breast cancer (15%, 95% CI: 9-24%). The detection of unsuspected distant metastases in these patients alters treatment and prognosis. NCCN guidelines should consider adding patients with stage IIB breast cancer for consideration of systemic staging with 18F-FDG-PET/CT at the time of initial diagnosis.