Clinicopathological Features of Cases with Primary Breast Cancer not Identified by 18F-FDG-PET

Several studies have reported that high F18-fluorodeoxyglucose (FDG) uptake is predictive of poor prognosis and aggressive features in patients with breast cancer. While these studies evaluated the prognostic value for cases with high FDG uptake, they did not elucidate the meaning of FDG negativity in primary breast cancer. In this study, we evaluated the clinicopathological features of breast cancer cases without FDG uptake. We retrospectively investigated the cases of 219 consecutive patients with primary breast cancer who underwent FDG-positron emission tomography (PET) preoperatively. Among the 219 patients, 25 (11.4%) did not have FDG uptake in the tumor. The 219 cases with breast cancer were divided into two groups based on the presence of FDG uptake in the primary tumor. The present univariate analysis revealed that histology, small invasive tumor size, high estrogen receptor (ER) or progesterone receptor (PgR) expression, low nuclear grade and absence of lymph node metastasis were significantly associated with negative FDG uptake in the primary tumor. On the other hand, the size of ductal spread was not significantly different between the two groups. Multivariate analysis revealed that small-size tumor invasion and lower nuclear grade were statistically significant. Among the 25 cases without FDG uptake, there was no recurrent disease in spite of there being no case that underwent chemotherapy, while 4 cases among the 194 cases with FDG uptake had disease recurrence. Our findings imply that preoperative FDG negativity in primary breast cancer is effective in predicting better prognosis, but is less effective in predicting ductal spread. Cases without FDG uptake in the primary tumor may have a lower risk of recurrent disease and may be able to safely avoid adjuvant chemotherapy.