Effects of topotecan treatment on nasal, buccal, and lingual mucosa in the rabbit: Light and transmission electron microscopic evaluation

Anticancer agents may cause side effects and some of which may be dose dependant. It is important for clinicians to see the effects on tissues histopathologically. The aim of this study was to investigate the effects of topotecan (hycamtin®), a topoisomerase I inhibiting anticancer agent, on nasal, buccal, and lingual mucosa of rabbits. The study was carried out in two groups each consisting of 20 rabbits. Rabbits in group I received i.v. topotecan (0.5 mg/kg once daily) for 3 days. Rabbits in group II received i.v. topotecan (0.25 mg/kg once daily) for 3 days. In group I and II, biopsies from the nasal, buccal, and lingual mucosa were taken on the fourth (1 day after the 3-day topotecan treatment) and 15th day (12 days after the 3-day topotecan treatment). Light and transmission electron microscopic (TEM) observations have shown that nasal mucosa was not affected by topotecan administration. Topotecan treatment resulted in the formation of some ulcerative lesions in the lingual mucosa especially on the lower surface of the tongue. On the dorsal surface, the epithelium showed highly edematous and degenerating cells and separations in the stratum granulosum. In the buccal mucosa, effects were similar. In lingual and buccal mucosa, healing was observed on the 15th day. The oral (lingual and buccal) mucosal side effects of topotecan were observed as reversible and not dose dependent. It was concluded that these side effects are not severe, and topotecan may be used safely in cancer treatment.