Hyposalivation due to chemotherapy exacerbates oral ulcerative mucositis and delays its healing

Cancer therapy including chemotherapy causes gland atrophy, resulting in low salivary secretion in cancer patients. Since saliva plays an important role in oral health, the dysfunction may exacerbate oral ulcerative mucositis (OUM), which is another side effect. Here, we investigated the effect of hyposalivation on OUM using sialoadenectomized rats and examined the effects of anticancer drugs on the salivary glands. As models for hyposalivation, the bilateral submandibular and sublingual glands except (2EXT) or together with (3EXT) the parotid glands were extracted. At 16 days after the procedure, OUM was experimentally developed by topical acetic acid treatment on the labial fornix region of the inferior incisors, and the severity and bacterial loading level were evaluated. The salivary gland weights and histology were analyzed after administration of the representative anticancer drugs 5-fluorouracil or cisplatin. The severity of OUM was greater in both the 3EXT and 2EXT rats and delayed the healing process compared with that in sham rats without salivary gland extraction. The healing process in the 3EXT rats was longer than that in the 2EXT rats. The number of colony-forming units in the ulcerative region from the 3EXT rats was 10-fold greater than that in the sham rats. Both 5-fluorouracil and cisplatin reduced glands weights and damaged the salivary glands. These results suggest that chemotherapy-induced hyposalivation exacerbates OUM and delays healing, most likely due to loss of salivary clearance and antimicrobial functions. This study illustrates the significance of oral health care for cancer patients undergoing chemotherapy.