The efficacy of screening with FDG-PET/CT for distant metastases in breast cancer patients scheduled for neoadjuvant systemic therapy.

Purpose: This study aims to identify which breast cancer patients benefit from the routine use of FDG-PET/CT in a large cohort of patients scheduled for neoadjuvant systemic therapy (NST).

Methods: A total of 1337 breast cancer patients eligible for NST were identified from a retrospective database between 2011 and 2020 at a single tertiary care hospital. All patients underwent staging with FDG-PET/CT prior to NST. The incidence and extent of asymptomatic distant metastases in different patient subgroups were determined, as well as the impact on treatment. Logistic regression analysis was used to identify prognostic patient and tumor characteristics.

Results: FDG-PET/CT detected distant metastases in 109 patients (8%). Initial clinical stage was a prognostic factor for the presence of distant metastases, with a significantly higher risk for stage 2b and 3 as opposed to lower stages (p < 0.001). The incidence of distant metastases was 3% (4/125) for stage 1, 2% (8/534) for stage 2a, 7% (24/354) for stage 2b and 23% (73/324) for stage 3. Other characteristics such as age, tumor subtype, histological type and grade were not correlated with the risk of distant metastases. Among the subset of patients with distant metastases, 46% received palliative treatment, while the remaining 54% were diagnosed with oligometastatic breast cancer and were treated with curative intent.

Conclusion: The results of the current study support the routine use of FDG-PET/CT for the detection of distant metastases in breast cancer patients with initial clinical stage 2b and 3, regardless of tumor subtype.