Quantitative FES-PET can predict response to hormonal therapy and may help guide treatment selection. Treatment selection using quantitative FES-PET in our patient series would have increased the rate of response from 23% to 34% overall, and from 29% to 46% in the subset of patients lacking HER2/neu overexpression. A multi-institutional collaborative trial would permit definitive assessment of the value of FES-PET for therapeutic decision making.

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The PET compound 18 F-fluoroestradiol ( 18 F-FES) has been developed and tested as an agent for the imaging of estrogen receptor (ER) expression in vivo. 18 F-FES uptake has been shown to correlate with ER expression assayed in vitro by radioligand binding; however, immunohistochemistry (IHC) rather than radioligand binding is used most often to measure ER expression in clinical practice. We therefore compared 18 F-FES uptake with ER expression assayed in vitro by IHC with both qualitative and semiquantitative measures. Methods: Seventeen patients with primary or metastatic breast cancer were studied with dynamic 18 F-FES PET; cancer tissue samples, collected close to the time of imaging, were assayed for ER expression by IHC. For each tumor, partial-volume-corrected measures of 18 F-FES uptake were compared with ER expression measured by 3 different ER scoring methods: qualitative scoring (0-31), the Allred score (0-10), and a computerized IHC index. Results: There was excellent agreement (r 5 0.99) between observers using IHC as well as the different methods of measuring ER content (P , 0.001). ER-negative tumors had 18 F-FES partial-volumecorrected standardized uptake values of less than 1.0, whereas ER-positive tumors had values above 1.1. Correlation coefficients for the different measures of ER content and the different measures of 18 F-FES uptake ranged from 0.57 to 0.73, with the best correlation being between the computerized IHC index and 18 F-FES partial-volume-corrected standardized uptake values. Conclusion: Our results showed good agreement between 18 F-FES PET and ER expression measured by IHC. 18 F-FES imaging may be a useful tool for aiding in the assessment of ER status, especially in patients with multiple tumors or for tumors that are difficult to biopsy.

Purpose: Advanced head and neck cancer shows hypoxia that results in biological changes to make the tumor cells more aggressive and less responsive to treatment resulting in poor survival. [F-18] fluoromisonidazole (FMISO) positron emission tomography (PET) has the ability to noninvasively quantify regional hypoxia. We investigated the prognostic effect of pretherapy FMISO-PETon survival in head and neck cancer. Experimental Design: Seventy-three patients with head and neck cancer had pretherapy FMISO-PETand 53 also had fluorodeoxyglucose (FDG) PETunder a research protocol from April 1994 to April 2004. Results: Significant hypoxia was identified in 58 patients (79%). The mean FMISO tumor/ blood max (T/B max ) was 1.6 and the mean hypoxic volume (HV) was 40.2 mL. There were 28 deaths in the follow-up period. Mean FDG standard uptake value (SUV) max was 10.8.The median time for follow-up was 72 weeks. In a univariate analysis,T/B max (P = 0.002), HV (P = 0.04), and the presence of nodes (P = 0.01) were strong independent predictors. In a multivariate analysis, including FDG SUV max , no variable was predictive at P < 0.05. When FDG SUV max was removed from the model (resulting in n = 73 with 28 events), nodal status and T/B max (or HV) were both highly predictive (P = 0.02, 0.006 for node andT/B max , respectively; P = 0.02 and 0.001for node and HV, respectively).Conclusions: Pretherapy FMISO uptake shows a strong trend to be an independent prognostic measure in head and neck cancer.