PET/CT-FDG vs Conventional Staging in Locally Advanced Breast Cancer

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In a Canadian study reported in the Journal of Clinical Oncology, Dayes et al found that positron-emission tomography/computed tomography–fluorodeoxyglucose (PET/CT-FDG) improved the detection of distant metastasis vs conventional staging in patients with locally advanced breast cancer. It also reduced the use of curative-intent combined-modality therapy.

Study Details

In the open-label trial, 369 patients with invasive ductal carcinoma of the breast and TNM stage III or IIb (T3N0, but not T2N1) from six centers in Ontario were randomly assigned between December 2016 and April 2022 to receive PET/CT-FDG (n = 184) or conventional staging including bone scan and CT of the chest/abdomen and pelvis (n = 185). The primary endpoint was upstaging to stage IV. A key secondary outcome measure was receipt of curative-intent combined modality therapy.

Key Findings

A total of 43 patients in the PET/CT-FDG group (23%) and 21 in the conventional staging group (11%) were upstaged to stage IV (relative risk = 2.4, 95% confidence interval [CI] = 1.4–4.2, P = .002). Upstaging to stage IV occurred in 4 (25%) of 16 patients in the PET/CT-FDG group and 4 (24%) of 17 in the conventional staging group with inflammatory breast cancer, and in 39 (23%) of 168 and 17 (10%) of 168 without inflammatory disease.

On the basis of the findings, treatment was altered in 35 (81%) of 43 patients in the PET/CT-FDG group and in 20 (95%) of 21 in the conventional staging group with upstaging to stage IV. Overall, 149 patients (81%) in the PET/CT-FDG group vs 165 patients (89.2%) in the conventional staging group received combined-modality treatment (absolute difference = 8.2%, 95% CI = 0.1–15.4, P = .03).

The investigators concluded, “In patients with [locally advanced breast cancer], [PET/CT-FDG] detected more distant metastases than conventional staging, and fewer [PET/CT-FDG] patients received combined modality therapy. Our randomized trial demonstrates the utility of the [PET/CT-FDG] staging strategy.”

They stated, “On the basis of the results, the Ontario Ministry of Health now funds [PET/CT-FDG] for the staging of patients with clinical stage IIb (T3 N0) and stage III breast cancer.”

Mark N. Levine, MD, MSc, of the Ontario Clinical Oncology Group, Juravinski Hospital, Hamilton, is the corresponding author for the Journal of Clinical Oncology article.

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