Resection versus expectant management of small incidentally discovered nonfunctional pancreatic neuroendocrine tumors.

BACKGROUND: Sporadic, nonfunctional pancreatic neuroendocrine tumors (NF-PNETs) are diagnosed with increasing frequency. We compared the risk of tumor growth, metastasis, and mortality between patients treated versus those treated expectantly. METHOD: A retrospective study of patients seen at our institution with sporadic NF-PNETs, with ≥ 12 months of follow-up. Kaplan-Meier analysis was performed. RESULTS: Between 1999 and 2014, 35 patients with an incidentally discovered nonfunctional PNET were identified. Twenty underwent resection and 15 were followed with imaging. In the operative group, 8 had NF-PNETs < 2 cm, while 12 had NF-PNETs ≥ 2 cm. In the nonoperative expectant management by serial imaging group, 10 had NF-PNETs < 2 cm while 5 had NF-PNETs ≥ 2 cm. Small NF-PNETs (<2 cm) in either the operative or nonoperative groups demonstrated no evidence of progression or metastasis (median follow-up of 27.8 months). Morbidity in the operative group was 35% with pancreatic pseudocyst the most common. CONCLUSION: Incidentally discovered NF-PNETs < 2 cm in size can be observed safely with serial imaging.

MicroRNA analysis of microdissected normal squamous esophageal epithelium and tumor cells.

Previous studies have identified several dysregulated microRNAs in esophageal squamous cell carcinoma (ESCC); however, to date there are no ex vivo analyses comparing expression levels of these regulatory molecules in esophageal squamous cell tumors versus patient-matched normal epithelium. We describe here a technical strategy to evaluate microRNAs in normal esophageal basal cells (NB), normal esophageal differentiated cells (ND), and tumor cells (T). Laser capture microdissection was used to procure target populations from five cases and 18 ESCC-associated microRNAs were measured by RT-qPCR. Five microRNAs (miR-25, miR-106b, miR-21, miR-203, and miR-145) demonstrated consistent differential expression in at least one of the three comparisons: T vs. NB, T vs. ND, or NB vs. ND. The potential regulatory role of the microRNAs in ESCC was further evaluated by correlating their expression with a matched mRNA dataset, which included the same five cases and cell populations. In conclusion, the present work demonstrates the feasibility of studying microRNA levels in precisely dissected cell populations from clinical samples, and sheds light on the molecular mechanisms associated with ESCC.

Effect of immunohistochemistry on molecular analysis of tissue samples: implications for microdissection technologies.

Laser-based tissue microdissection is an important tool for the molecular evaluation of histological sections. The technology has continued to advance since its initial commercialization in the 1990s, with improvements in many aspects of the process. More recent developments are tailored toward an automated, operator-independent mode that relies on antibodies as targeting probes, such as immuno-laser capture microdissection or expression microdissection (xMD). Central to the utility of expression-based dissection techniques is the effect of the staining process on the biomolecules in histological sections. To investigate this issue, the authors analyzed DNA, RNA, and protein in immunostained, microdissected samples. DNA was the most robust molecule, exhibiting no significant change in quality after immunostaining but a variable 50% to 75% decrease in the total yield. In contrast, RNA in frozen and ethanol-fixed, paraffin-embedded samples was susceptible to hydrolysis and digestion by endogenous RNases during the initial steps of staining. Proteins from immunostained tissues were successfully analyzed by one-dimensional electrophoresis and mass spectrometry but were less amenable to solution phase assays. Overall, the results suggest investigators can use immunoguided microdissection methods for important analytic techniques; however, continued improvements in staining protocols and molecular extraction methods are key to further advancing the capability of these methods.