Exosomes in Head and Neck Squamous Cell Carcinoma

Mucosal human papillomaviruses (HPV) are the cause of cervical cancer and likely a subset of head and neck squamous cell carcinomas (HNSCC), yet the global prevalence and type distribution of HPV in HNSCC remains unclear. We systematically reviewed published studies of HNSCC biopsies that employed PCR-based methods to detect and genotype HPV to describe the prevalence and type distribution of HPV by anatomic cancer site. Geographic location and study size were investigated as possible sources of variability. In the 5,046 HNSCC cancer specimens from 60 studies, the overall HPV prevalence was 25.9% [95% confidence interval (95% CI), 24.7-27.2]. HPV prevalence was significantly higher in oropharyngeal SCCs (35.6% of 969; 95% CI, 32.6-38.7) than oral SCCs (23.5% of 2,642; 95% CI, 21.9-25.1) or laryngeal SCCs (24.0% of 1,435; 95% CI, 21.8-26.3). HPV16 accounted for a larger majority of HPV-positive oropharyngeal SCCs (86.7%; 95% CI, 82.6-90.1) compared with HPV-positive oral SCCs (68.2%; 95% CI, 64.4-71.9) and laryngeal SCCs (69.2%; 95% CI, 64.0-74.0). Conversely, HPV18 was rare in HPV-positive oropharyngeal SCCs (2.8%; 95% CI, 1.3-5.3) compared with other head and neck sites [34.1% (95% CI, 30.4-38.0) of oral SCCs and 17.0% (95% CI, 13.0-21.6) of laryngeal SCCs]. Aside from HPV16 and HPV18, other oncogenic HPVs were rarely detected in HNSCC. Tumor site-specific HPV prevalence was higher among studies from North America compared with Europe and Asia. The high HPV16 prevalence and the lack of HPV18 in oropharyngeal compared with other HNSCCs may point to specific virus-tissue interactions. Small sample size and publication bias complicate the assessment of the prevalence of HPV in head and neck sites beyond the oropharynx.

Answer questions and earn CME/CNE The recently released eighth edition of the American Joint Committee on Cancer (AJCC) Staging Manual, Head and Neck Section, introduces significant modifications from the prior seventh edition. This article details several of the most significant modifications, and the rationale for the revisions, to alert the reader to evolution of the field. The most significant update creates a separate staging algorithm for high-risk human papillomavirus-associated cancer of the oropharynx, distinguishing it from oropharyngeal cancer with other causes. Other modifications include: the reorganizing of skin cancer (other than melanoma and Merkel cell carcinoma) from a general chapter for the entire body to a head and neck-specific cutaneous malignancies chapter; division of cancer of the pharynx into 3 separate chapters; changes to the tumor (T) categories for oral cavity, skin, and nasopharynx; and the addition of extranodal cancer extension to lymph node category (N) in all but the viral-related cancers and mucosal melanoma. The Head and Neck Task Force worked with colleagues around the world to derive a staging system that reflects ongoing changes in head and neck oncology; it remains user friendly and consistent with the traditional tumor, lymph node, metastasis (TNM) staging paradigm. CA Cancer J Clin 2017;67:122-137. © 2017 American Cancer Society.

Exosomes offer distinct advantages that uniquely position them as highly effective drug carriers. Comprised of cellular membranes with multiple adhesive proteins on their surface, exosomes are known to specialize in cell-cell communications and provide an exclusive approach for the delivery of various therapeutic agents to target cells. In addition, exosomes can be amended through their parental cells to express a targeting moiety on their surface, or supplemented with desired biological activity. Development and validation of exosome-based drug delivery systems are the focus of this review. Different techniques of exosome isolation, characterization, drug loading, and applications in experimental disease models and clinic are discussed. Exosome-based drug formulations may be applied to a wide variety of disorders such as cancer, various infectious, cardiovascular, and neurodegenerative disorders. Overall, exosomes combine benefits of both synthetic nanocarriers and cell-mediated drug delivery systems while avoiding their limitations.