Southwest Oncology Centers

Neuroendocrine tumors (NETs) originate from neuroendocrine cells, which receive neural input and play a key role in transmitting signals by secreting bioactive substances such as monoamines (e.g., serotonin), peptides (e.g., somatostatin), and hormones (e.g., insulin) that regulate a wide range of physiological functions. While NETs in the liver are typically metastatic, often originating from other sites in the gastrointestinal (GI) tract, they can, in rare cases, manifest as primary tumors in the liver. These are referred to as primary hepatic neuroendocrine tumors (PHNT). We present the case of a 62-year-old male patient diagnosed with PHNT confirmed through imaging and immunohistochemistry analysis. Given the rarity of this diagnosis, there are no established treatment guidelines for PHNT. In this case, lattice radiotherapy (LRT) via TomoTherapy (TomoTherapy, Inc. in Madison, WI) was selected as the first-line treatment approach for the tumor.

The aim of this study was to identify which patient characteristics are associated with the highest likelihood of positive findings on 11C-acetate PET/computed tomography attenuation correction (CTAC) (PET/CTAC) scan when imaging for recurrent prostate cancer.

From 2007 to 2011, 250 11C-acetate PET/CTAC scans were performed at a single institution on patients with prostate cancer recurrence after surgery, brachytherapy, or external beam radiation. Of these patients, 120 met our inclusion criteria. Logistic regression analysis was used to examine the relationship between predictability of positive findings and patients' characteristics, such as prostate-specific antigen (PSA) level at the time of scan, PSA kinetics, Gleason score, staging, and type of treatment before scan.

In total, 68.3% of the 120 11C-acetate PET/CTAC scans were positive. The percentage of positive scans and PSA at the time of scanning and PSA velocity (PSAV) had positive correlations. The putative sensitivity and specificity were 86.6% and 65.8%, respectively, when a PSA level greater than 1.24 ng/mL was used as the threshold for scanning. The putative sensitivity and specificity were 74% and 75%, respectively, when a PSAV level greater than 1.32 ng/mL/y was used as the threshold. No significant associations were found between scan positivity and age, PSA doubling time, Gleason score, staging, or type of treatment before scanning.

This retrospective study suggests that threshold models of PSA greater than 1.24 ng/mL or PSAV greater than 1.32 ng/mL per year are independent predictors of positive findings in 11C-acetate PET/CTAC imaging of recurrent prostate cancer.