Management of Radiotherapy-related Xerostomia With Green Tea and Peppermint

The goal of this study is to evaluate the clinical effectiveness of a mix of (green tea and peppermint) mouth rinse using the subjective dry mouth score as a primary objective and to assess the effect of that mix on the salivary flow rate and objective dry mouth score as a secondary objective.

The Global Cancer Observatory from the World Health Organization estimates that head and neck cancer (HNC) incidence will reach approximately 1.5 million cases worldwide in 2020. Nevertheless, radiotherapy (RT) remains one of the cornerstone standard therapies to attenuate HNC progression. The advancement of linear accelerator (LINAC) technologies together with intensity-modulated radiation therapy (IMRT) techniques have enhanced the precision and efficiency of fractionated RT for HNC. Emerging research efforts have also been undertaken to understand these RT technologies' ability to spare the function of neighboring healthy tissues or organs like the salivary glands (SG). Despite these research advances, a large majority of HNC patients who undergo RT display irreversible dry mouth symptoms (xerostomia) due to high radiation sensitivity of salivary gland (SG) secretory cells. This gland damage is thought to be triggered by an RT-induced loss of acinar cells and a potential impairment of the parasympathetic innervation and vascularization. Hence, the remaining integral SG stem/progenitor cells post-RT will define the true regenerative ability of the SG organ. Cytoprotectant agents like amifostine have been recommended to prevent RT damage to SG cells. Amifostine is the only US Food and Drug Administration (FDA) approved drug for this prevention strategy. In Phase III clinical trials, amifostine was found to reduce xerostomia severity in subjects with grade two and above; however, more than 50% of subjects still presented acute xerostomia symptoms and oral mucosa inflammation. Moreover, amifostine has a very narrow therapeutic window. Therefore, frequent administration is required leading to severe side effects in more than half of the treated individuals. These side effects can lead to the discontinuation of amifostine treatment and RT delay in 25% of HNC patients. The high frequency of reported side effects and its high cost and low-quality evidence of efficacy from several clinical trials make amifostine a less promising pharmacological approach. Thus, novel pharmaceuticals are necessary to prevent SG damage and maintain the acinar epithelial and stem/progenitor cell populations in the SG organ. In vitro and in vivo studies indicate green tea polyphenols (GTPs)/(-)-epigallocatechin-3-gallate (EGCG) as potential natural agents for xerostomia management, potentially delaying salivary dysfunction through molecular mechanisms. Researchers highlighted EGCG's role in suppressing autoantigens, influencing epithelial cell proliferation, and modulating antioxidant enzyme expression in salivary glands. Peppermint essential oil is another herbal preparation with strong antibacterial and cooling effects. As a safe herbal preparation, peppermint essential oil has been found to be effective in alleviating the pain associated with aphthous stomatitis and managing dental plaque.