18FDG–PET–CT improves breast cancer staging

By Lynda Williams, Senior medwireNews Reporter

A prospective study has shown fluorodeoxyglucose positron emission tomography/computed tomography (¹⁸FDG-PET-CT) to be a powerful tool for the detection of nodal and distant metastatic disease in patients with breast cancer.

When applied to 254 patients with stage II or III disease diagnosed by clinical examination, magnetic resonance imaging, or ultrasound, ¹⁸FDG-PET-CT findings led to a change of American Joint Committee on Cancer stage in 30.3% of patients, report David Groheux (Hôpital Saint-Louis, Paris, France) and co-authors.

¹⁸FDG-PET-CT had the greatest impact on patients with the most advanced disease, leading to a stage change in 16.1% of stage IIB patients, 31.7% of stage IIIA patients, 51.4% of stage IIIB patients, and 47.1% of stage IIIC patients.

"It is hoped that the information provided at initial staging might lead to better management of these patients who account for the largest mortality rate from breast cancer," say Groheux et al.

As ¹⁸FDG-PET-CT findings resulted in a stage change in just 4.5% of stage IIA patients, however, the team believes that the imaging technique may be "justified" only for patients with stage IIB disease or above.

Stage modification was prompted by the detection of previously unsuspected disease in the infraclavicular, supraclavicular, or internal mammary nodes, or distant metastases by ¹⁸FDG-PET-CT.

Following up patients with clinical IIB or greater disease, 3-year disease-specific survival was significantly shorter for the patients with distant metastases on ¹⁸FDG-PET-CT compared with those who had no evidence of distant metastases, at 57% versus 88%.

In multivariate analysis, distant metastatic disease on ¹⁸FDG-PET-CT and a triple-negative breast cancer phenotype were the only significant prognostic factors for disease-specific survival. The relative risk for death for M1 versus M0 patients was 26.60, while the relative risk for triple-negative phenotype versus other phenotypes was 18.58.

"The remarkable progression in the yield of ¹⁸FDG-PET-CT with advancing clinical stage and the correlation between PET-CT findings and prognosis are strong arguments that the overwhelming majority of patients classified as M+ on the basis of ¹⁸FDG-PET-CT have true-positive metastases," the researchers say.

Nevertheless, they emphasize that as their findings were in a single institution, the research must be repeated in other settings.

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