Metabolic tumor volume measured by F-18 FDG PET/CT reflects histopathological characteristics of primary breast cancer

Objectives The purpose of this study is to compare metabolic tumor volume (MTV) and maximum SUV (SUVmax) as predictors of histopathological characteristics in patients with primary breast cancer.

Methods Eighty three patients with biopsy-proven breast cancer underwent pre-operative FDG PET/CT and contrast enhanced CT (CECT) within 1 month (mean 3.7 ± 4.2 days). CECT was used for the determination of anatomical extent of primary breast cancer. Volume of interest (VOI) fully encasing primary tumor was drawn, and then SUVmax and MTV (at the cut-off value of SUV 2.5) were measured. Multivariate logistic regression analysis was used for evaluating correlation between metabolic parameters and histopathological characteristics.

Results Pathologic analysis revealed invasive ductal carcinoma in 74 patients (89%), invasive lobar carcinoma in 7 patients (8%), and invasive papillary carcinoma in 2 patients (3%). SUVmax and MTV of primary breast malignancy showed moderate correlation (r=0.530, p<0.001). Both SUVmax and MTV were significantly higher in patients with tumor invasive size > 2 cm, histological grade 3, negative PR, and positive for distant metastasis. In patients with negative ER, only MTV was significantly higher (p=0.013). In multivariate logistic regression analysis, MTV was a significant factor correlated with tumor invasive size (p=0.002), histological grade (p<0.001), ER (p=0.010), PR (p=0.008) and distant metastases (p=0.012).

Conclusions Our preliminary results show that MTV only reflect histopathological characteristics in breast cancer. Therefore, MTV could be a useful parameter to predict prognosis in patients with primary breast cancer