Abstract 5038: Chrysotile asbestos fibers in tissue adjacent to laryngeal squamous cell carcinoma in cases with a history of occupational asbestos exposure

Abstract

Abstract Asbestos describes a group of naturally occurring fibrous silicate mineral compounds. Its use dates back thousands of years but became widespread in the late 19th century through the late 20th century due to its favorable industrial properties, including its strength, flexibility and thermal properties, with peak use in the United States occurring in the 1970s. Asbestos has been associated with a number of chronic respiratory diseases, including malignancy, and was first linked to mesothelioma and lung cancer in the early to mid part of the 20th century. Despite the known health risks, asbestos is not universally banned and is still in use in many countries (including the United States), with an estimated 125 million occupationally-exposed individuals worldwide. In addition to mesothelioma and lung cancer, asbestos has also been implicated as a risk factor for squamous cancers involving the upper airway, in particular laryngeal and pharyngeal carcinoma, as indicated by recent meta-analyses; however, evidence for the latter associations is based solely on epidemiologic data from observational studies. The primary objective of this work was to attempt to strengthen the evidence via empirical demonstration of persistent asbestos fibers embedded in the tissue surrounding the tumor, thus providing a more definitive biological link between exposure and disease. Six HPV-negative laryngeal and pharyngeal squamous cell carcinoma cases were selected from a large population-based case-control study of head and neck cancer, plus one case with no occupational exposure history as a control. Briefly, detailed occupational history was available for 1,056 head and neck cancer cases enrolled through major teaching hospitals located in Boston, Massachusetts. Occupational data was reviewed to identify those with an occupational history of asbestos exposure. Tissue cores were obtained from adjacent non-neoplastic tissue in tumor blocks from the initial primary tumor resection from a subset of 6 cases with a history of occupational-asbestos exposure and 1 case with no reported occupational exposure (control). A count of asbestos fibers >5um was performed on the cores from each case at Duke University using a scanning electron microscope equipped with an energy dispersive x-ray analyzer (EDXA). Despite the low volume of input tissue, chrysotile asbestos fibers were identified in 3/6 of evaluated cases with a history of occupational asbestos exposure; all 3 cases had tumors originating in the larynx. This is the first study to demonstrate the presence of asbestos fibers in the larynx of cases with laryngeal squamous cell carcinoma, adding an additional line of physical evidence implicating asbestos as an etiologic factor for laryngeal squamous cell carcinoma. Citation Format: Stephanie K. Wronkiewicz, Victor Roggli, Damaris Kuhnell, Rondi A. Butler, Karl T. Kelsey, Scott M. Langevin. Chrysotile asbestos fibers in tissue adjacent to laryngeal squamous cell carcinoma in cases with a history of occupational asbestos exposure [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5038.