Cancer-associated fibroblasts (CAFs) are major components of the carcinoma microenvironment that promote tumor progression. However, the mechanisms by which CAFs regulate cancer cell migration are poorly understood. In this study, we show that fibronectin (Fn) assembled by CAFs mediates CAF–cancer cell association and directional migration. Compared with normal fibroblasts, CAFs produce an Fn-rich extracellular matrix with anisotropic fiber orientation, which guides the cancer cells to migrate directionally. CAFs align the Fn matrix by increasing nonmuscle myosin II- and platelet-derived growth factor receptor α–mediated contractility and traction forces, which are transduced to Fn through α5β1 integrin. We further show that prostate cancer cells use αv integrin to migrate efficiently and directionally on CAF-derived matrices. We demonstrate that aligned Fn is a prominent feature of invasion sites in human prostatic and pancreatic carcinoma samples. Collectively, we present a new mechanism by which CAFs organize the Fn matrix and promote directional cancer cell migration.

The American Joint Committee on Cancer (AJCC) staging system for all cancer sites, including gastroenteropancreatic neuroendocrine tumors (GEP‐NETs), is meant to be dynamic, requiring periodic updates to optimize AJCC staging definitions. This entails the collaboration of experts charged with evaluating new evidence that supports changes to each staging system. GEP‐NETs are the second most prevalent neoplasm of gastrointestinal origin after colorectal cancer. Since publication of the AJCC eighth edition, the World Health Organization has updated the classification and separates grade 3 GEP‐NETs from poorly differentiated neuroendocrine carcinoma. In addition, because of major advancements in diagnostic and therapeutic technologies for GEP‐NETs, AJCC version 9 advocates against the use of serum chromogranin A for the diagnosis and monitoring of GEP‐NETs. Furthermore, AJCC version 9 recognizes the increasing role of endoscopy and endoscopic resection in the diagnosis and management of NETs, particularly in the stomach, duodenum, and colorectum. Finally, T1NXM0 has been added to stage I in these disease sites as well as in the appendix.

Mesenteric tumor deposits (MTDs) are not included in the American Joint Committee on Cancer (AJCC) staging system for midgut small intestinal neuroendocrine tumors (NETs). We examined the prognostic significance of MTDs associated with midgut NETs. Hematoxylin and eosin slides from 132 resected jejunal/ileal NETs were reviewed for AJCC tumor stage, lymph node (LN) metastasis, MTDs, and hepatic metastases. MTDs were defined as discrete irregular mesenteric tumor nodules discontinuous from the primary tumor. Clinical or pathologic evidence of metastases and survival data were abstracted from electronic medical records. The cohort included 72 male and 60 female patients with a median age of 60 years. LN metastasis, MTDs, and liver metastasis were present in 80%, 68%, and 58% of patients, respectively. Female sex and presence of MTDs were independent predictors of liver metastasis. The odds ratio for hepatic metastasis in the presence of MTDs was 16.68 (95% confidence interval [CI], 4.66-59.73) and 0.81 (95% CI, 0.20-3.26) for LN metastasis. Age, MTDs, and hepatic metastasis were associated with disease-specific survival (DSS) in univariate analysis. Primary tumor histologic grade, pT3/T4 stage, and LN metastasis were not associated with DSS. Multivariate analysis of liver metastasis-free survival stratified by tumor grade showed that MTDs were associated with adverse outcomes. The hazard ratio for MTDs was 4.58 (95% CI, 1.89-11.11), compared with 0.98 (95% CI, 0.47-2.05) for LN metastasis. MTDs, but not LN metastasis, in midgut NETs are a strong predictor for hepatic metastasis and are associated with poor DSS.

Currently, molecular testing in colorectal cancer (CRC) is aimed at detecting Lynch syndrome and predicting response to anti–epidermal growth factor receptor (EGFR) therapies. However, CRC is a complex disease, with at least 3 molecular pathways of carcinogenesis. The importance of the EGFR signaling pathway in colorectal carcinogenesis is underscored by the availability of anti-EGFR monoclonal antibodies for the treatment of some metastatic CRCs. Potentially, mutations in any of the genes in the EGFR signaling pathway may be associated with prognosis and may predict response to anti-EGFR or other targeted therapies. Although not currently the standard of care, molecular testing of CRCs is expanding to include mutational analysis of the genes in the EGFR pathway, in addition to more widely performed tests for identifying cancers with high microsatellite instability. Multiplex molecular prognostic panels for therapeutic decision making in stage II CRCs also represent expanding use of molecular testing for this common cancer.