br Methods br Results br Discussion Peritoneal micro metasta

Methods
Results
Discussion Peritoneal micro-metastases are a common occurrence and portend poor prognosis for many malignancies including ovarian, gastric, and pancreatic cancer (Ferrone et al., 2006; Merchant et al., 1999; Bentrem et al., 2005; Burke et al., 1998; Yachida et al., 2002; Yoshimura et al., 1984). The current standard method of detection relies on cytologic evaluation of harvested isradipine according to for cytomorphologic characteristics of malignant transformation. This test is highly specific and clinically relevant: positive results are associated with very poor prognosis, early intraabdominal recurrence, and death (Jimenez et al., 2000a; Gold et al., 2007; Ferrone et al., 2006; Merchant et al., 1999; Bentrem et al., 2005; Burke et al., 1998; Yachida et al., 2002; Yoshimura et al., 1984). However, when very few free cancer cells are present in the peritoneum, they may be difficult to identify by cytomorphologic criteria alone. In addition, mesothelial atypia and inflammatory infiltrates can complicate cytologic analysis of peritoneal fluid. Pancreatic and gastric cancer patients undergo DL with the goal of accurate preoperative staging and are often found to have false negative cytology. Many of these patients then undergo resection with curative intent only to develop early postoperative recurrence in the peritoneal cavity. NV1066-mediated eGFP expression has been shown to aid in detection of malignant deposits in preclinical animal models of pleural, peritoneal, and lymphatic disease, and in preparations of malignant cells mixed with benign cells from various organs in vitro (Adusumilli et al., 2005, 2006a, b, 2011; Eisenberg et al., 2006; Stanziale et al., 2004). In the current study, we clinically test a virally-mediated fluorescence detection assay with NV1066 was employed to detect peritoneal micro-metastases in pancreatic cancer patients. In this cohort of pancreatic adenocarcinoma patients evaluated prospectively, virally-mediated fluorescence increased the yield of diagnosis of peritoneal micro-metastasis by 46% over conventional cytology. This increased sensitivity appears to be clinically relevant. Patients undergoing resection with curative intent, all of whom had negative conventional cytology, had a median recurrence free survival of only 6.5months if eGFP positive, versus 12.2months if eGFP negative (P=0.01). This finding confirms that the presence of eGFP positive cells in peritoneal washings is a sensitive indicator of micrometastasis and that these cells do go on to develop into early recurrence. As is true for pancreas cancer in general, the most common site of first clinical recurrence after curative-intent resection for patients in this trial was the liver, followed by the peritoneum. eGFP positivity predicted not only intraperitoneal, but any recurrence. This finding suggests that the presence of eGFP positive cells may be an indicator of aggressive tumor biology. Median disease specific survival for the eGFP-negative patients was 36.2months, double that of eGFP-positive patients. Although not statistically significant, this survival is comparable if not superior to the 20–24month median survival expected after curative resection and adjuvant therapy. Median survival of this magnitude for pancreatic cancer patients has only been reported in neoadjuvant therapy trials. This finding suggests that virally-mediated fluorescence detection of peritoneal micrometastasis may have an important role in patient selection for surgery. Virally-mediated fluorescence detection can be incorporated into the DL procedure with essentially no increased morbidity or risk to the patient, and can enhance the sensitivity of detection of peritoneal micrometastatic disease. This assay is inexpensive, rapid, and easy to perform and interpret. eGFP positivity could potentially be incorporated into DL for pancreatic cancer patients. If adopted into clinical practice, eGFP positive patients, like those with positive cytology, could be offered neoadjuvant or definitive systemic therapy. While this pilot study focuses on pancreatic adenocarcinoma, there is reason to believe that this highly sensitive and specific assay is applicable to essentially all intraabdominal malignancies. Virally mediated fluorescence has the potential to enhance the sensitivity of DL for the detection of occult micrometastatic disease for many cancers (Kemeny et al., 2006).