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More than twice as many patients with locally advanced breast cancer were upstaged to stage IV when they underwent positron emission tomography-computed tomography (PET-CT) compared with conventional staging, researchers reported.

Mark N. Levine, MD, MSc, of Juravinski Hospital - Hamilton Health Sciences in Ontario, and colleagues randomized 369 patients to 18F-labeled fluorodeoxyglucose PET-CT or conventional staging consisting of a bone scan plus CT of the thorax and abdomen. In the PET-CT group, 43 patients (23%) were upstaged compared with 21 (11%) in the conventional group (absolute difference 12%, P=0.02).

Consequently, fewer patients in the PET-CT group received combined modality treatment compared with the conventional group (81% vs 89%, P=0.03), according to the study in the .

"To our knowledge, our trial is the first and only randomized controlled trial on this subject," the team wrote. "In patients with locally advanced breast cancer, PET-CT detected more distant metastases than conventional staging, and fewer PET-CT patients received combined modality therapy. Our randomized trial demonstrates the utility of the PET-CT staging strategy."

In the following interview, Levine, who is also chair of Oncology, Breast Cancer Research, and Clinical Epidemiology & Biostatistics at McMaster University, discussed further details about the study and its implications.

Why is it significant that fewer of the PET-CT patients received combined modality treatment?

Levine: Patients with locally advanced breast cancer usually receive neoadjuvant chemotherapy followed by breast cancer surgery and local regional radiation -- combined modality treatment. If metastases are detected, many patients will avoid the toxicity of chemotherapy because they are administered less aggressive therapy.

How should the results of this study affect clinical practice or policy?

Levine: Our trial provides Level I evidence on the effectiveness of the staging strategy. It has already informed policy in Ontario as PET-CT is now covered by the provincial health plan. We expect the NCCN [National Comprehensive Cancer Network] will upgrade the strength of the recommendation for PET-CT in their guideline.

You noted an interesting finding, that treatment didn't change in about 20% of upstaged PET-CT patients, but it did change in most of the upstaged conventional imaging patients. Why do you think that was the case?

Levine: One possibility is that in a few patients, that PET-CT detected metastases of low tumor burden -- e.g., mediastinal nodes, or oligometastases, and the oncologist chose to treat the patient with aggressive potentially curative treatment.

Another interesting observation was that nearly 100% of upstaged PET-CT patients were found to have positive regional nodes. What insight does this provide about how breast cancer spreads?

Levine: It supports both step-step local spread and/or hematogenous spread.

Finally, what do you plan to explore in your longer-term follow-up of these patients?

Levine: Good question. We have collected quality-of-life and cost data for the first 12 months following randomization. This will be used for an economic analysis. In addition, we plan to obtain 3-year and 5-year follow-up information on recurrence and mortality using record linkage. This will inform whether earlier detection of breast cancer spread influences the clinical course of the disease or is merely a form of lead-time bias: earlier detection results in "giving the patient more time with disease."

Read the study here.