Chemical-Induced Oral Squamous Cell Neoplasms in Rodents: An Overview of NTP 2-Year Cancer Studies.

Oral cancer is the seventh most common malignancy worldwide, and lifestyle factors participate in its development. Rodent studies can help identify substances that contribute to its development and provide information on the early stages of carcinogenicity. The National Toxicology Program (NTP) has conducted more than 500 short-term and 2-year toxicology and carcinogenicity studies in rodents, and some of the tested compounds resulted in oral cancer. Our goal was to review the NTP carcinogenic studies to describe those chemicals that have oral carcinogenic outcome in rodents. For this project, we reviewed the results from all NTP carcinogenicity studies and a board-certified veterinary pathologist reviewed the slides from all neoplasms in the oral cavity that were considered treatment related. We have identified 26 chemicals with an adverse effect in the oral cavity. Fourteen chemicals demonstrated clear evidence of carcinogenicity in the oral cavity. We provide information on the carcinogenic findings in rodents together with a detailed description of the morphologic aspects of the oral cancers and speculate that the carcinogenic effects can be induced by different pathological modes of action. The findings reviewed here provide indicators for potential oral carcinogenesis processes in rodent models, which can be further investigated in future mechanistic studies.

The effect of radiotherapy on taste sensation in head and neck cancer patients - a prospective study.

BACKGROUND: One of the main side effects of head and neck (H&N) radiation therapy (RT) is alteration in taste sensation. It causes significant morbidity and has a major effect on quality of life (QoL). The aim of this study was to prospectively define the effect of RT on taste sensation (general, and four basic tastes) and correlate these findings with changes in saliva secretion and QoL questionnaires. METHODS: Patients with H&N cancer treated with RT, in which the oral cavity was expected to receive a mean dose of 30 Gray (Gy). Patients were evaluated by Whole-Saliva Sialometry, validated Taste Strips and European Organization for Research and Treatment of Cancer H&N QoL questionnaires prior to RT (T0), mid-point of radiotherapy dose (T1), at the end of radiotherapy (T2) and 1 (T3), 3 (T4) and 12 months (T5) after completion of treatment course. RESULTS: Twenty-eight patients were recruited, and 21 patients completed study procedures and were analyzed. Median age was 66 years (range 18-90). The most common tumor site was the oral cavity. The median prescribed radiation dose to the high dose volume was 66 (range 60-70). The median mean and max dose to the oral cavity were 25.1 (range 14-69) and 64.9 (range 30-70), respectively. There was a significant decrease in overall taste sensation between T0 and T1 and T2. With specific tastes, there were significant decreases in sensation of sweet and salty, a trend with bitter and no change with sour. All returned to baseline at T3 and onwards. There was no significant correlation between the max or mean dose to the oral cavity and overall taste sensation or between doses to different areas of the tongue and overall or specific tastes. At T0 there was a significant positive correlation between overall taste sensation and whole-saliva sialometry, and at T1 and T2 there were strong trends. There were significant declines in QoL scores during RT. CONCLUSIONS: We found a significant immediate reduction in taste sensation due to RT in H&N cancer patients with taste recovery 1 month after treatment completion. There were strong trends to a correlation with saliva production that requires further exploration.