頭頸癌放射治療患者之口腔照護模式研究與 DMBA誘發倉鼠頰囊袋癌之放射治療效果評估

對放射線特別敏感的頭頸部腫瘤，尤其如扁桃腺癌、鼻咽癌等而言，放射治療常為臨床治療之首選，可單獨、合併化學治療或為輔助療法；但患者易因放療後遺症，如唾液腺功能障礙和猛爆性齲齒等，嚴重影響生活品質，對牙醫師和腫瘤科醫師都是一長期挑戰。另一方面，建立動物研究模式將有助於放射腫瘤學的長期發展。本研究之第一單元為頭頸癌放射治療患者之口腔照護模式研究。收集高醫口腔病理科放治化療門診370位頭頸癌中的232位鼻咽癌和62位口腔癌患者(共佔所有頭頸癌患之79.5 %)為主要研究對象。對鼻咽癌患者而言，放療後齲齒數增加極為顯著(7.18 ±7.10 與2.45±2.85; c2= 46.32, p < 0.0001)，而氟托的配製與否和回診率具極顯著之相關性(c2=48.56, p < 0.0001)。相對之，口腔癌患者放療後齲齒並未增加，且回診率與氟托配製與否亦無關，但其存活率雖較鼻咽癌為低，回診率卻與其存活狀況有顯著相關。因此，鼻咽癌與口腔癌患者應有不同的照顧模式。鼻咽癌的口腔照護應以完整的長期照護，減少因口乾引起之齲齒等口腔疾病為主，鼓勵居家塗氟與定期回診，口腔癌則以減輕口腔症狀為主，避免感染，提高其口腔舒適度。第二單元為建立癌症動物的放療模式。將53隻倉鼠隨機分為治療組A與B及控制組C到G後，A與B組於頰囊塗抹誘癌劑7, 12-dimethyl benz[a]anthrance(DMBA)，每週三次，共12週，再以分次照射方式，以6MV直線加速器每週二次，每次7Gy，分別給予放射量21與42 Gy；未塗抹誘癌劑的C與D組亦給予放射量21與42 Gy，E組與F組分別於頰囊塗抹DMBA與礦物油；而G組則未給予任何處置。實驗結果發現：倉鼠頰囊袋於癌化後及放射治療後，頰囊袋容積明顯減少三分之一與二分之一。分次放射的模式下，C與D組倉鼠頰囊並無明顯的黏膜炎產生。照射21Gy可使倉鼠在外觀上有殘餘腫瘤的動物數減少(5/9，55.55% )，但鏡檢下之內生型腫瘤數卻顯著增多；照射42Gy時，外觀留有殘餘腫瘤的動物數更少(1/9，11.11% )，且鏡檢下的外生型腫瘤數及總腫瘤數均明顯減少。放療前後鏡檢下的外生型腫瘤數及總腫瘤數於三組間具極顯著之統計差異(p<0.0001, p<0.001)。放療的主要機制為壞死，但鏡檢下仍有殘餘腫瘤細胞，顯示腫瘤復發之可能性。免疫組織化學染色之結果顯示：放射引發的自戕反應，部份與p53及一氧化氮合成酶的表現有關；而對腫瘤細胞自戕反應的影響，抑制細胞自戕蛋白質survivin 於殘餘腫瘤細胞中呈陽性反應，證實其與放射抗性有關； 42Gy下，p53不表現，可能由於iNOS的作用使放射敏感性增加。此外，由TUNEL染色可觀察唾液腺的早期幅射損傷。頷下腺中的漿液細胞及管道細胞的自戕現象較高，但黏液細胞幾乎不表現，且頷下腺的放射敏感度高於耳下腺，並伴隨劑量而增。總括以上，本研究之結論如下：(1) 放療前的牙科治療計劃應同時納入頭頸癌患者的放療計劃中；(2) 倉鼠頰囊袋癌模型可應用於正常組織與癌細胞之分次放射效應之研究。

關鍵字

口腔照護；頭頸癌放射治療；分次放射； DMBA誘癌；倉鼠

並列摘要

Radiotherapy (RT) is an effective treatment for radiosensitive head and neck (H&N) cancers, especially for carcinomas of nasopharynx(NPC) and tonsil. It is wildly used either alone or concurrent with chemotherapy. The side effects of RT, particularly the irreversible salivary gland damage and rampant caries severely affects the quality of life of surviving patients, these complications present long-term challenges to both dentists and oncologists. On the other hand, the establishment of an animal caner model for RT will facilitate the development on radiooncological sciences. Therefore, the aim of the fist part of this study was to construct an oral care model of H&N radiotherapy patients. A total of 232 NPC and 62 oral cancer patients underwent regular recall dental examinations and treatments according to a standard protocol of our Dental Department. The mean number of carious tooth of the NPC patient population during/after RT was significantly higher than the population before RT (7.18±7.10 vs. 2.45±2.85; c2= 46.32, p<0.0001). As compared patients using fluoride trays to those without using, the former had a significantly higher rate of dental follow-up compliance (c2=48.56, p<0.0001). Therefore, fluoride tray fabrication is recommended for dentate NPC patients receiving RT. By contrast, the oral cancer RT patients, their caries rate was not related to radiation experience, and their dental compliances were related to their survival condition rather than fluoride trays. Therefore, the oral care model should be modified for NPC and oral cancer patients according to their different treatment modalities. The objective of the second part study was to establish an animal cancer model for RT. Fifty-three hamsters was divided randomly into the experimental groups A, B and control groups C to G. After treating the pouches of groups A and B animals with 7, 12-dimethyl benz[a]anthrance (DMBA) thrice a week for 12 weeks, the heads of the animals received fractionated radiation (7Gy/twice/week) of a total dose of 21Gy and 42Gy with a 6 MV linear accelerator, respectively. The untreated pouches of groups C and D animals were similarly irradiated. The pouches of groups E and F animals were treated with DMBA or mineral oil for 12 weeks, respectively. The pouches of group G animals remained untreated throughout the experiment. The volume of buccal pouches were significantly decreased to 2/3 and less than 1/2 after carcinoma induction and RT in both groups A and B when comparing with group G. There were no obvious mucositis after fractionated radiation in groups C and D. 55.55% in groups A (5 in 9 animals) and 11.11% in B (1 in 9 animals) have visible residual exophytic tumors after RT. Microscopically, the endophytic tumor numbers in group A was significant increased when compared with group E. Both the exophytic tumor and total tumor numbers were decreased for group B animal. There were significant differences on the exophytic tumor and total tumor numbers among groups A, B and E (p<0.0001, p<0.001). Moreover, the main radiogenic killing effect is necrosis, but the residual tumor cells indicating the possibilities of recurrence. Immunohistological examinations showed p53 and iNOS were associated with the radiation-induced apoptosis of the hamster buccal pouches. The radioresistancy of DMBA-induced buccal pouch carcinoma of hamster may be related to over-expression of survivin, an antiapoptosis protein. Although p53 was not expressed in animals receiving high radiation dose, iNOS may increase the radiosensitivity. Furthermore, via TUNEL staining, the early apoptosis was found in serous cells and ductal cells rather than mucous cells of the parotid and submandibular glands, but submandibular glands were more radiosensitive than parotid counterparts. In conclusion, our study indicate that, (1) a pre-RT dental care regimen should be conducted simultaneously with the H&N cancer patient’s treatment plan to treat the disease; (2) the hamster pouch cancer model could be employed to study the fractionated radiation effect on both cancer cells and normal tissues.