Intratumoral uptake heterogeneity in (18)F-FDG PET has been associated with patient treatment outcomes in several cancer types. Textural feature analysis is a promising method for its quantification. An open issue associated with textural features for the quantification of intratumoral heterogeneity concerns its added contribution and dependence on the metabolically active tumor volume (MATV), which has already been shown to be a significant predictive and prognostic parameter. Our objective was to address this question using a larger cohort of patients covering different cancer types. A single database of 555 pretreatment (18)F-FDG PET images (breast, cervix, esophageal, head and neck, and lung cancer tumors) was assembled. Four robust and reproducible textural feature-derived parameters were considered. The issues associated with the calculation of textural features using co-occurrence matrices (such as the quantization and spatial directionality relationships) were also investigated. The relationship between these features and MATV, as well as among the features themselves, was investigated using Spearman rank coefficients for different volume ranges. The complementary prognostic value of MATV and textural features was assessed through multivariate Cox analysis in the esophageal and non-small cell lung cancer (NSCLC) cohorts. A large range of MATVs was included in the population considered (3-415 cm(3); mean, 35; median, 19; SD, 50). The correlation between MATV and textural features varied greatly depending on the MATVs, with reduced correlation for increasing volumes. These findings were reproducible across the different cancer types. The quantization and calculation methods both had an impact on the correlation. Volume and heterogeneity were independent prognostic factors (P = 0.0053 and 0.0093, respectively) along with stage (P = 0.002) in non-small cell lung cancer, but in the esophageal tumors, volume and heterogeneity had less complementary value because of smaller overall volumes. Our results suggest that heterogeneity quantification and volume may provide valuable complementary information for volumes above 10 cm(3), although the complementary information increases substantially with larger volumes.

In this analysis, the role of metabolic imaging with fluorine 18 fluorodeoxyglucose (FDG) in breast cancer is reviewed. The analysis was limited to recent works by using state-of-the-art positron emission tomography (PET)/computed tomography (CT) technology. The strengths and limitations of FDG PET/CT are examined in various clinical settings, and the following questions are answered: Is FDG PET/CT useful to differentiate malignant from benign breast lesions? Can FDG PET/CT replace sentinel node biopsy for axillary staging? What is the role of FDG PET/CT in initial staging of inflammatory or locally advanced breast cancer? What is the role of FDG PET/CT in initial staging of clinical stage IIA and IIB and primary operable stage IIIA breast cancer? How does FDG PET/CT compare with conventional techniques in the restaging of cancer in patients who are suspected of having disease recurrence? What is the role of FDG PET/CT in the assessment of early response to neoadjuvant therapy and of response to therapy for metastatic disease? Some recommendations for clinical practice are given.

Many studies have pointed out the role of ¹⁸F-FDG PET/CT (or ¹⁸F-FDG PET) in patients with clinical stage III or II breast cancer. ¹⁸F-FDG PET/CT might advantageously replace other staging procedures, such as bone scanning and possibly contrast-enhanced CT of the thorax or abdomen–pelvis. We discuss the findings, locoregional or distant, that can be expected in different categories of breast cancer and their impact on prognosis and management. We also discuss the role of ¹⁸F-FDG PET/CT in restaging and how ¹⁸F-FDG PET/CT compares with conventional techniques in restaging for patients with suspected disease recurrence. We conclude with some recommendations for clinical practice and future research.

This study prospectively evaluated the yield of fluorodeoxyglucose positron emission tomography/computed tomography ( ¹⁸ FDG-PET-CT) in patients with clinical stages II and III breast cancer and the impact of PET-CT results on prognosis. In the course of 71 months, 254 consecutive patients with clinical stages II and III breast cancer (based on clinical examination, mammography, breast magnetic resonance imaging, and locoregional ultrasonography) underwent ¹⁸ FDG-PET-CT. The yield was assessed in the whole population and for each American Joint Committee on Cancer subgroup. The prognostic impact of PET-CT findings was analyzed. Tests of statistical significance were two-sided. ¹⁸ FDG-PET-CT changed the clinical stage in 77 of 254 patients (30.3%; 95% confidence interval [CI] = 25.0% to 36.2%). It showed unsuspected N3 disease (infraclavicular, supraclavicular, or internal mammary nodes) in 40 patients and distant metastases in 53. PET-CT revealed distant metastases in 2.3% (1 of 44) of clinical stage IIA, 10.7% (6 of 56) of stage IIB, 17.5% (11 of 63) of stage IIIA, 36.5% (27 of 74) of stage IIIB, and 47.1% (8 of 17) of stage IIIC patients. Among 189 patients with clinical stage IIB or higher disease and adequate follow-up, disease-specific survival was statistically significantly shorter in the 47 patients scored M1 on ¹⁸ FDG-PET-CT in comparison with those scored M0, with a three-year disease-specific survival of 57% vs 88% ( P < .001). In multivariable analysis, only distant disease on PET-CT and triple-negative phenotype were statistically significant prognostic factors. The relative risk of death was 26.60 (95% CI = 6.60 to 102.62) for M1 vs M0 patients. The yield of ¹⁸ FDG-PET-CT appeared substantial in patients with clinical stage IIB or higher breast cancer. In these patients, ¹⁸ FDG-PET-CT provided powerful prognostic stratification.