唾液腺放射性损伤及其防护

放射治疗在头颈肿瘤的地位已得到广泛认同,但放疗并发症不容忽视,最常见的是放射性口干。其主要机制为放射诱导的唾液腺损伤,早期和晚期损伤的机制不同。目前对唾液腺放射防护的研究主要集中在放射防护剂、放射技术、基因转移技术等多个方面。     

头颈部肿瘤放疗对唾液腺的损伤

唾液腺损伤是头颈部肿瘤放疗的最常见并发症之一,放射性唾液腺损伤及功能障碍的机制包括射线对唾液腺细胞的直接损伤、射线间接引起唾液腺组织营养血管的闭锁及放射引起的自身免疫介导唾液腺损伤.另外,放射性唾液腺损伤及功能障碍还涉及到腺体体积的缩小和分泌功能的减退、以及对损伤的预防和治疗等.     

中药放射防护剂的研究进展

放疗是治疗恶性肿瘤的重要手段,伴随着放射治疗常会产生不同程度的放射副反应或放射损伤h’。从细胞分子水平上讲,放射损伤主要表现为DNA损伤、生物膜损伤、免疫系统损伤和造血系统损伤’‘,‘’。而许多有效的化学放射防护剂都有较大的毒副作用［‘］,因此,大大降低...     

放射性核素定量检测放疗后唾液腺功能的方法

放射性核素定量检测放疗后唾液腺功能的方法曹秀华，张庆坤，贾莹莹，唐谨，吴文凯头颈部肿瘤如鼻咽癌等放疗后会损伤唾液腺功能，过去采取收集每分钟唾液量的方法，以判定涎腺功能，但由于放疗后，病人唾液少，收集困难，此方法欠准确。本文介绍放射核素检测诞腺功能的方...     

放射诱导鼻咽癌细胞凋亡的研究现状

鼻咽癌（NPC）是我国高发的恶性肿瘤之一，放射治疗是其主要的治疗手段。目前研究表明，放射与细胞凋亡存在密切关系，放射可诱导肿瘤细胞发生凋亡，并加速细胞凋亡过程而使更多的肿瘤细胞死亡，从而使肿瘤发生消退。探讨和研究射线与NPC细胞凋亡的关系，对了解放射诱导NPC细胞死亡的分子机制、放疗技术的改进和放射防护等具有重要的现实意义。     

肠道菌群对放射性肠损伤防护作用的基础与临床研究进展

人类肠道中定殖着各种菌群,放射线作用下菌群分布会发生变化,同时菌群本身对肠道组织的放射敏感性也有一定调节作用,而人为对肠道菌群进行干预能有效改善放疗后的急性肠道损伤^[1-4]。笔者为探讨肠道菌群对放射性肠损伤的防护作用,用“radiation、enteritis、gut flora”为检索词检索了PubMed文库1990年以来文献,主要围绕肠道菌群在放射性肠损伤中的作用及分子机制进行选择,包含了临床试验和动物实验。现就肠道菌群与肠道放射性损伤及放射敏感性之间关系和相关机制进行总结。     

头颈部恶性肿瘤放射治疗后唾液腺功能减退的防治

放射治疗是头颈部恶性肿瘤治疗的主要方法之一 ,应用常规照射时腮腺、颌下腺等大涎腺常受到较高剂量的照射 ,引起涎腺分泌功能减退 ,口干是患者常见的后遗症。放射治疗引起的唾液量减少一方面是由于直接损伤涎腺细胞 ,另一方面间接引起唾液腺组织基质纤维化及其营养血管的闭锁。Ｓｔｅｐｈｅｎｓ等[1] 观察到涎腺细胞的损伤在单次剂量如 2Ｇｙ照射后 2 4ｈ就已发生 ,细胞形态变化呈凋亡特征 (细胞核深染、核固缩、核碎裂及核融解等 ) ,故认为涎腺细胞损伤的主要机制是射线引起细胞凋亡。放射能够导致分泌颗粒包膜的过氧化损伤 ,使涎液成分如…     

前列腺癌放疗直肠防护技术研究进展

放射治疗是前列腺癌的重要治疗手段, 前列腺与直肠关系密切, 直肠防护至关重要。近年来, 直肠防护技术层出不穷, 本文对前列腺癌放疗中直肠防护技术进行了系统综述, 包括放疗技术改进、图像引导、直肠球囊扩张、直肠隔离凝胶的使用等对直肠的防护作用, 为临床提高前列腺癌放疗安全, 降低直肠放射损伤提供参考。     

鼻咽癌放疗后口干燥症的发生机制及防治研究进展

口干燥症是鼻咽癌放疗后常见且不可逆的并发症，目前其发生机制尚未完全明确，亦无有效的治疗手段。本文综述唾液腺放射性损伤的机制及其临床防治研究进展。     

放射性唾液腺损伤机理的研究进展

放射性唾液腺损伤是头颈部肿瘤放射治疗常见的并发症,其形成机理尚未完全明确。目前认为,放疗后导致的唾液腺结构和功能的损伤是其主要因素,包括唾液腺腺泡与导管的结构改变以及血管、淋巴管与神经损伤后导致唾液的分泌和排泄功能改变等。现就近年来放射性唾液腺损伤机理的研究进展作一综述。     

Scintigraphy in prediction of the salivary gland function after gland-sparing intensity modulated radiation therapy for head and neck cancer

BACKGROUND AND PURPOSE: To evaluate salivary gland scintigraphy in prediction of salivary flow following radiation therapy. PATIENTS AND METHODS: Twenty patients diagnosed with head and neck cancer were treated with intensity modulated radiation therapy with an intention to spare the salivary gland function. The total quantitative saliva secretion was measured prior to and 6 and 12 months after therapy, and the function of the major salivary glands was monitored using Tc-99m-pertechnetate scintigraphy. Two models were designed for prediction of the post-treatment salivary flow: an average model, based on the average proportions of saliva produced by each of the four major glands in healthy subjects, and an individual model, based on saliva produced by each gland as measured by scintigraphy prior to therapy. These models were compared with volume-based (Lyman) normal tissue complication probability models using two published sets of model parameters. RESULTS: The D(50) for the parotid and the submandibular gland function assessed at 6 and 12 months after radiotherapy was approximately 39Gy. The scintigraphy-based individual model predicted well the measured post-treatment saliva flow rates. The correlation coefficient between the predicted stimulated and the measured saliva flow rate was 0.77 (p<0.0001) at 6 months and 0.55 (p=0.034) at 12 months after completion of radiotherapy. The relative changes in unstimulated and stimulated salivary flow rates showed similar dependency on the cumulative radiation dose. CONCLUSIONS: Salivary gland function assessed by scintigraphy prior to radiotherapy is useful in prediction of the residual salivary flow after radiotherapy.     

Some factors influencing salivary function when treating with radiotherapy

Salivary flow rate (FR) was studied in 29 patients treated with external irradiation to bead and neck areas. “Resting” saliva samples were collected before, during the radiotherapy course and follow-up. Several parameters were investigated: field arrangement, amount of salivary glands irradiated, dose to these glands, initial FR, its recovery during and after irradiation, and influence of therapy interruption (split course) in FR. We found that the level of the upper border of the field is a critical factor when using parallel-opposed lateral fields to the upper neck area and lateral face. More than 50% of the parotids have to be outside the fields to prevent severe dryness. Neck fields which do not encompass salivary glands do not decrease salivary secretion. There is some relation between the initial FR and the dose necessary to produce dryness: patients with high initial salivary FR require higher doses. FR recovery occurs during weekend interruptions before xerostomia develops. Interruptions of therapy for more than two weeks during the radiotherapy course prior to development of dryness might decrease late xerostomia, at least in patients with high initial FR. Objective recovery of the FR has not been observed after treatment in spite of the subjective improvement in the sensation of dryness of some patients.     

颌下腺移位术预防鼻咽癌放疗后口干燥症的长期效果

目的:评价颌下腺移位术预防鼻咽癌放疗后口干燥症的长期效果.方法:70例鼻咽癌患者随机分为试验组36例和对照组34例.试验组在行常规放疗前将颌下腺移位至颏下区,放疗时颏下区设置挡块.~(99)T_c核素扫描检测放疗前后颌下腺功能,测定放疗前后唾液分泌量,放疗后60个月进行口干程度问卷调查,统计5年生存率.结果:放疗后60个月:试验组颌下腺摄取、分泌功能均明显较对照组好,两者之间有显著性差异,P值分别为0.000和0.000;试验组和对照组唾液量的平均值分别为1.65g和0.73g(P=0.000);试验组中度至重度口干燥症的发生率亦显著低于对照组(12.9% vs 78.6%,P=0.000);试验组和对照组的5年生存率分别为86.1%和82.4%,两者之间无显著性差异(P=0.67).结论:颌下腺移位术不影响鼻咽癌远期疗效,预防鼻咽癌放疗后口干燥症的长期效果良好,可改善鼻咽癌患者放疗后的生存质量.     

Expression of Wnt-1, TGF-β and related cell-cell adhesion components following radiotherapy in salivary glands of patients with manifested radiogenic xerostomia

Background

Radiation-induced xerostomia still represents a common symptom following radiotherapy of head and neck malignancies, which significantly impairs the patient’s quality of life. In this cross-sectional study, human salivary glands were investigated to assess the role of Wnt/β-catenin and TGF-β pathways in the pathogenic process of radiogenic impairment of salivary function.

Methods

Irradiated human salivary glands were investigated in patients with manifested xerostomia. Alteration of Wnt-1 and cell-cell adhesion was evaluated immunohistologically as well as changes in the expression of TGF-β were assessed in salivary gland tissue.

Results

We assessed two alteration patterns in which Wnt-1 expression represents one change along with up-regulation of β-catenin and E-cadherin in irradiated but viable acinar cells. Increased expression of tenascin-C was observed in sites of epithelial-mesenchymal interaction and loss of cell-cell adhesion was assessed in translocated epithelial cells in the stroma.

Conclusion

Increased transdifferentiation and remodeling of acinar structures was associated with decrease of viable acinar structures. The role of Wnt and TGF signaling may provide a potential therapeutic approach to prevent radiation-induced damage to salivary glands during radiotherapy for head and neck cancer.     

益气养阴活血方对鼻咽癌放疗后涎腺功能的影响

 目的　观察益气养阴活血方治疗放射性涎腺反应的临床疗效。方法　2005年1月至2005年12月对鼻咽癌患者进行了中药治疗放射性涎腺反应的临床研究。治疗组30例患者在放疗期间应用中药益气养阴活血方；对照组30例在放疗期间使用常规处理。结果　两组患者均完成放疗，但对照组中有5例患者放疗过程中曾中止1～2周；急性放射性腮腺改变的发生程度两组差异无统计学意义（χ2 = 2.387，P = 0.122）；两组放射性腮腺改变的发生时间比较，治疗组明显迟于对照组（χ2 = 13.106，P = 0.000）；治疗后两组患者Karnofsky评分比较，治疗组优于对照组（χ2 = 12.685，P = 0.013）；放疗的客观疗效比较，治疗组缓解率90.0 %，对照组86.7 %（χ2 = 0.638，P = 0.727）。结论　益气养阴活血方能减低鼻咽癌放射性涎腺反应临床症候，明显推迟急性放射性反应出现的时间，减轻了患者的痛苦，显著提高鼻咽癌放疗完成率，提高患者的生活质量，中药配合放疗对鼻咽癌有较好的治疗作用。     

Estimation of long-term salivary gland damage induced by radiotherapy

A classification is proposed for estimating salivary gland damage induced by radiotherapy to the head and neck. The volume of salivary glands irradiated was evaluated, and their relative proportions of whole saliva output were calculated. Stimulated salivary flow rate was measured in 61 patients treated with radiotherapy for head and neck malignancies. A highly significant negative correlation was found between the classification of salivary gland damage and stimulated salivary flow rate. The volume of the major salivary glands irradiated seems to be the most important factor affecting the postirradiation salivary flow after a curative dose of radiotherapy. If possible, partial sparing of the salivary glands may help to keep the patient's salivary secretion at an acceptable level and promote protection against dental caries. Most patients irradiated to the head and neck, however, need an effective prophylactic programme for the rest of their lives in order to preserve their teeth.     

Adénomes pléomorphes parotidiens récidivants : place de la radiothérapie

Parotid pleomorphic adenoma is the most frequent tumor of salivary glands. The prognosis depends on the recurrences because they could lead to iatrogenic events (facial paralysis). Moreover the risk of malignant transformation increases with the number of local relapses. This article aims at reviewing histological and radiological criteria and the surgical techniques. To improve local control, adjuvant irradiation (in first intention or after recurrence) may be useful but is still controversial for benign tumors in young patients with a risk of radio-induced cancer. We listed studies in which adjuvant radiotherapy was used so as to define its place in the treatment strategy. Prognostic factors were found by some authors. Other studies have to be done before strong evidence-based recommendations are issued.