RSNA: PET/CT accurately assesses breast cancer patients after neodjuvant chemo

CHICAGO—FDG-PET/CT is useful in the evaluation of neoadjuvant chemotherapy (NAC) efficacy and in management of locally advanced breast cancer patients, according to a single-center study presented Nov. 25 at the 2012 Radiological Society of North America (RSNA).

In her presentation, the study’s lead author Sachiko Kiyoto, MD, said, that “the predictive and prognostic assessment [of FDG-PET in these patients] is controversial, even now.” Thus, she and her colleagues from the Shikoku Cancer Center in Matsuyama City, Japan, sought to evaluate whether changes in FDG tumor uptake at baseline and after NAC could predict pathological complete response (pCR) and disease-free survival after surgery.

In the study, the researchers evaluated 87 consecutive patients (90 lesions) who underwent FDG PET/CT at baseline and after NAC between 2006 and 2010. They measured the maximum standardized uptake values (SUVmax), and defined the pCR as pathological stage T0 and N0 after NAC. Finally, they evaluated the ability of ΔSUVmax to differentiate pathological findings (pCR vs. non-pCR) by receiver-operating-characteristic curve (ROC) analysis.

At surgery, 12 lesions had pCR, whereas 78 lesions had non-pCR. By the ROC analysis, 80.8 percent of ΔSUVmax was the threshold value for differentiation between pCR and non-pCR, with the area under the curve of 0.775.

The sensitivity, specificity, positive predictive value, negative predictive value and accuracy were 92 percent, 62 percent, 27 percent, 98 percent and 62 percent, respectively.

On clinical follow-up after surgery, Kiyoto and colleagues observed recurrence in 12 percent of the 41 metabolic responders (ΔSUVmax, greater than 80.8 percent), whereas in 37 percent of the 49 metabolic non-responders (ΔSUVmax, less than 80.8 percent). Kaplan-Meier curve shows disease-free survival rate of metabolic responders was significantly higher than that of non-responders.

“The recurrence rate of non-pCR patients was lower than pCR patients, but not significantly,” said Kiyoto. 

Metabolic non-responders after NAC show non-pCR with high probability and low disease-free survival rate on follow-up after surgery, the researchers concluded.