Tumour markers and FDG PET/CT for prediction of disease relapse in patients with breast cancer

The aim of the study was to assess the role of CA 15.3, CT and positron emission tomography (PET)/CT in patients with breast cancer and suspected disease relapse after primary treatment. We studied 111 consecutive patients (mean age 61 +/- 12 years) with previous breast cancer, already treated and with clinical or biochemical suspicion of disease relapse. All patients underwent CT and (18)F-fluorodeoxyglucose (FDG) PET/CT. In all patients, the value of CA 15.3 was compared to PET/CT and CT. The final diagnosis of relapse was established by invasive and noninvasive follow-up and was compared with CA 15.3, CT and PET/CT results. Univariate and multivariate analyses were used to identify the independent predictors of disease relapse and receiver-operating characteristic (ROC) curve for the identification of optimal CA 15.3 cutoff. Of all patients, 40 (36%) showed an increased CA 15.3 value, CT was positive in 73 (66%), whereas at PET/CT imaging 64 (58%) showed positive findings for disease relapse. Of 40 patients with increased marker levels, 22 patients had positive CT and 30 positive PET/CT (55 vs 75%, p < 0.001). At the end of follow-up, recurrence occurred in 32 (29%) patients, 16 (50%) of whom showed high levels of CA 15.3. PET/CT predicted relapse in 26 (81%) patients, whereas CT correctly identified 23 (72%). At univariate analysis, recurrence was significantly associated with high CA 15.3 values (p < 0.05) and positive PET/CT (p < 0.005). At multivariable analysis only positive PET/CT remained an independent predictor of disease relapse (p < 0.05). ROC analysis showed an optimal cutoff point for CA 15.3 of 19.1 U/ml (AUC 0.65, p < 0.01) to individuate positive PET/CT. FDG PET/CT is more sensitive than CT and CA 15.3 in the evaluation of disease relapse. PET/CT might be considered a complementary imaging technique during follow-up in patients with breast cancer.