[18FDG-PET in patients with in situ breast carcinomas. A cause of false negative results].

Background And Objective: To study the behaviour of 18F-FDG-PET in patients with in situ breast carcinomas.

Patients And Method: The study group included 19 women with a tumor size between 0.8 and 2.2 cm. An uptake in breast with a SUV > 1.9 was considered as positive.

Results: 18F-FDG-PET was positive in 8 patients (SUV; range 0.6-2.8; 1.64 [0.59]) and only when the tumor size was higher than 1 cm. Likewise, only in the PET-positive tumors, an inverse (r = -0.637) and positive (p < 0.05) correlation between SUV and weight of patients was observed. When we compared the results with those obtained in 28 patients having infiltrating ductal carcinomas of the breast, we observed that the 18F-FDG-PET was positive only in tumors > 1 cm also, but the percentages of positives (89%) were higher than those obtained in in-situ carcinoma, regardless of tumor size.

Conclusions: The percentage of positive results of 18F-FDG-PET in in-situ breast carcinomas and the SUV are lower than those observed in infiltrating ductal carcinomas, regardless of tumor size. Those carcinomas can be a source of false negative results with such imaging technique.