Pathologic Effects of External Beam Irradiation on Human Vocal Folds

Clinical Question: What exactly are the pathologic changes that occur in the vocal folds after external beam irradiation?

Background: With the increase in chemoradiation for laryngeal cancer as an organ-preserving modality, it is imperative that we define the effects on the larynx so that patients can be counseled appropriately. These include hoarseness, dysphagia, aspiration and xerostomia and can even lead to a nonfunctional larynx. The goal was to study these changes at a cellular and molecular level.

Study design: Tissue selection was done by collecting irradiated laryngeal specimens, and pathology and medical records were reviewed to exclude specimens that had recurrent or persistent disease. The part of the laryngeal specimen that included the primary malignancy was also excluded so that only the effect of radiation on the tissue would be studied. Tissue analysis was performed in a blinded fashion. Specific tissue stains were used, quantified by optical density. Histomorphometry and immunohistochemistry were used to study structure and extracellular matrix in the vocal folds.

Setting: University medical center.

Synopsis: Thirteen irradiated larynges were studied. A mean of 30 months had elapsed after irradiation. Chemotherapy records were lacking. Increased muscle and collagen disorganization were found in the vocalis muscle, and increased collagen, hyaluronic acid, fibronectin and MMP-9 were found in the superficial lamina propria. The effects of radiation in the larynx increased over time.

Bottom line: This elegant study showed that external beam radiation results in significant pathologic changes in the vocal fold that have long-term effects on voice and other laryngeal functions. Therapeutic interventions can target these changes.

Reference: Berg EE, Kolachala V, Branski RC, et al. Pathologic effects of external beam irradiation on human vocal folds. Ann Otol Rhinol Laryngol. 2011;120(11):748-754.