ABSTRACT
PURPOSE: PET/CT is useful in preoperative evaluation of invasive breast cancer (IBC) to predict axillary metastasis and staging workup. The usefulness is unclear in cases of ductal carcinoma in situ (DCIS) diagnosed at biopsy before surgery, which sometimes is upgraded to IBC after definitive surgery. The aim of this study is to find out the usefulness of PET/CT on DCIS as a preoperative evaluation tool. METHODS: We investigated 102 patients preoperatively diagnosed with DCIS who subsequently underwent definitive surgery between 2010 and 2015. The uptake of 18F-fluorodeoxyglucose was graded by visual and semiquantitative methods. We analyzed the maximum standardized uptake value (SUVmax) of each patient with clinicopathologic variables. We determined optimal cutoff values for SUVmax by receiver operating characteristic curve analysis. RESULTS: Fifteen cases out of 102 cases (14.7%) were upgraded to IBC after surgery. The SUVmax was higher in patients upgraded to IBC (mean: 2.56 vs. 1.36) (P = 0.007). The SUVmax was significantly higher in patients who had symptoms, palpable masses, lesions over 2 cm in size and BI-RAD category 5. Both visual and semiquantitative analysis were significant predictors of IBC underestimation. SUVmax of 2.65 was the theoretical cutoff value in ROC curve analysis in predicting the underestimation of IBC. The underestimation rate was significantly higher in patients with SUVmax >2.65 (P < 0.001), over the moderate enhanced uptake on visual analysis (P < 0.001). CONCLUSION: PET/CT can be used as a complementary evaluation tool to predict the underestimation of DCIS combined with the lesion size, palpable mass, symptomatic lesion, and BI-RAD category.