PET/CT bests contrast CT at monitoring metastatic breast cancers

PET/CT is superior to contrast-enhanced CT when it comes to predicting both progression-free and disease-specific survival in patients with metastatic breast cancer, according to a study published online May 1 in the European Journal of Nuclear Medicine and Molecular Imaging.

Christopher Riedl, MD, PhD, of Weill Cornell and colleagues followed 65 patients with metastatic breast cancer who were treated with first- or second-line systemic therapy in prospective clinical trials.

The team evaluated response to contrast CT and FDG PET/CT using, respectively, RECIST and PERCIST criteria.

They found that all responders by RECIST (n = 22) were also responders by PERCIST, but 40 percent (17 of 43) of non-responders by RECIST were responders by PERCIST.

Further, responses according to RECIST and PERCIST both correlated with progression-free survival, but PERCIST showed a significantly higher predictive accuracy (concordance index for progression-free survival: 0.70 vs. 0.60).

Also:

• One-year progression-free survival for responders vs. non-responders by RECIST was 59 percent vs. 27 percent, compared to 63 percent vs. 0 percent by PERCIST.
• Four-year disease-free survival of responders and non-responders by RECIST was 50 percent and 38 percent, respectively (p = 0.2, concordance index: 0.55) as compared to 58 percent vs. 18 percent for PERCIST (p < 0.001, concordance index: 0.65).

In addition, response on PET/CT proved “a significantly better predictor for disease-specific survival than disease control on contrast CT,” the authors report.

In patients with metastatic breast cancer, tumor response on PET/CT “appears to be a superior predictor of progression-free survival and disease-specific survival than response on CE-CT,” Riedl et al. conclude.

They add that monitoring tumor response by PET/CT “may increase the power of clinical trials using tumor response as an endpoint and may improve patient management in clinical routine.”