Radiation apoptosis of serous acinar cells of salivary and lacrimal glands

Xerostomia and xerophthalmia are common and potentially serious local side effects of radiotherapy for head and neck cancer. Clinical observations supported by experimental findings show that radiation, even in low doses, causes acute diminutions of saliva and tears by rapidly killing the serous cells of the salivary and lacrimal glands, respectively. Serous acini of salivary and lacrimal glands have similar developmental, morphologic, and functional characteristics. Serous acinar cells are functionally mature, secretory epithelial cells that normally do not divide and are long lived. Irradiation of the salivary and lacrimal glands of rhesus monkeys resulted in selective death of serous acinar cells within 24 hours. The paradigm for acute radiation seroadenosis is intermitotic or interphase cell death caused by apoptosis.     

Mobilization of bone marrow stem cells by granulocyte colony-stimulating factor ameliorates radiation-induced damage to salivary glands.

PURPOSE: One of the major reasons for failure of radiotherapeutic cancer treatment is the limitation in dose that can be applied to the tumor because of coirradiation of the normal healthy tissue. Late radiation-induced damage reduces the quality of life of the patient and may even be life threatening. Replacement of the radiation-sterilized stem cells with unirradiated autologous stem cells may restore the tissue function. Here, we assessed the potential of granulocyte colony-stimulating factor (G-CSF)-mobilized bone marrow-derived cells (BMC) to regenerate and functionally restore irradiated salivary glands used as a model for normal tissue damage. EXPERIMENTAL DESIGN: Male-eGFP+ bone marrow chimeric female C57BL/6 mice were treated with G-CSF, 10 to 60 days after local salivary gland irradiation. Four months after irradiation, salivary gland morphology and flow rate were assessed. RESULTS: G-CSF treatment induced homing of large number of labeled BMCs to the submandibular glands after irradiation. These animals showed significant increased gland weight, number of acinar cells, and salivary flow rates. Donor cells expressed surface markers specific for hematopoietic or endothelial/mesenchymal cells. However, salivary gland acinar cells neither express the G-CSF receptor nor contained the GFP/Y chromosome donor cell label. CONCLUSIONS: The results show that BMCs home to damaged salivary glands after mobilization and induce repair processes, which improve function and morphology. This process does not involve transdifferentiation of BMCs to salivary gland cells. Mobilization of BMCs could become a promising modality to ameliorate radiation-induced complications after radiotherapy.     

Comparison of radiosensitivity of rat parotid and submandibular glands after different radiation schedules.

BACKGROUND AND PURPOSE: To investigate the radiosensitivity of rat parotid and submandibular gland functioning after local single dose, conventional fractionated and accelerated fractionated irradiation. METHODS: The salivary glands of male albino Wistar rats were locally irradiated with a single dose (15 Gy) or a calculated (alpha/beta; 9.6) biological effective dose of fractionated irradiation equal to this, viz. conventional fractionation (32 Gy in 16 fractions of 2 Gy/day, five times/week) or accelerated fractionation (32 Gy in 16 fractions of 2 Gy, two fractions/day). Parotid and submandibular/sublingual saliva samples were collected by means of miniaturized Lashley cups before and up to 240 days after irradiation. Salivary flow rate, lag phase and amylase secretion were used as parameters for the assessment of salivary gland function. At the end of the experiments the animals were sacrificed and the glands processed for histopathological examination. RESULTS: Up to 120 days after irradiation no differences were observed between the glands or between the different irradiation schedules. Beyond 120 days, however, the parotid gland performed better in flow rate and lag phase after fractionated irradiation, when compared to the submandibular gland. The observed differences in function corresponded with the observed late histopathological changes. The parotid gland contained more acinar cells and had a higher gland weight. No differences were observed between both fractionation schedules on each gland. CONCLUSIONS: The main observation from this study is the higher radiosensitivity of the submandibular gland compared to the parotid gland for late effects after fractionated irradiation. This may have implications for the treatment planning in case of radiotherapy for head and neck cancer.     

Sparing the parotid glands and surgically transferred submandibular gland with helical tomotherapy in post-operative radiation of head and neck cancer: a planning study.

BACKGROUND AND PURPOSE: To evaluate the feasibility of sparing the parotid glands and surgically transferred submandibular gland (SMG) by intensity modulated radiotherapy (IMRT) in post-operative cases of head and neck cancer (HNC). MATERIALS AND METHODS: Ten patients (larynx-2, base of tongue-4, tonsil-3, and unknown primary-1; pathologic stages III-IV) who underwent SMG transfers on the side of N0 neck along with definitive surgery were selected for this study. IMRT planning was done retrospectively using helical tomotherapy approach. Planning objective was to deliver 60 Gy to PTV1 and 54 Gy to PTV2 while maintaining the mean dose to the total parotid volume (TPV) and SMG less than 26 Gy. RESULTS: The mean dose (+/-SD) to the TPV and SMG were 25+/-0.6 Gy and 23+/-1.9 Gy, respectively. The D(95) for PTV1 and PTV2 were 59.9+/-0.1 Gy and 54.9+/-0.3 Gy, respectively, satisfying our planning goal for PTV coverage. The D(99) for PTV1 and PTV2 were 58.2+/-0.7 Gy and 49.5+/-2.2 Gy, respectively, showing that sparing the salivary glands did not result in underdosing of the PTVs. CONCLUSIONS: By combining the gland transfer and IMRT, the mean dose to TPV and transferred SMG could be reduced to less than 26 Gy in post-operative patients of HNC.     

Structural and functional characteristics of irradiation damage to parotid glands in the miniature pig

PURPOSE: To evaluate the effects of a solitary megadose protocol of ionizing radiation (IR) on the structure and function of the miniature pig (minipig) parotid gland. METHODS AND MATERIALS: Fourteen minipigs were subjected to either 15 or 20 Gy to one parotid gland with a linear accelerator, whereas another four minipigs served as non-IR controls. Salivary flow rates and salivary chemistries were measured pre-IR and 4 and 16 weeks post-IR. A quantitative assessment of gland weight and acinar area and detailed serum chemistry and hematologic analyses were also performed. RESULTS: Parotid flow rates decreased by approximately 50% either with 20 Gy at 4 weeks, or 15 Gy at 16 weeks post-IR. In the 20 Gy group, salivary flow rates were reduced by approximately 80% at 16 weeks post-IR. A significant decrease in salivary calcium and amylase and an increase of salivary potassium levels were found in both IR groups. There were also transient alterations in serum chemistry and hematology parameters post-IR. Parotid gland weights were significantly decreased (-50%) in the 15 and 20 Gy groups at 4 and 16 weeks post-IR. Additionally, the acinar cell area in glands of both IR groups was significantly reduced from that in control glands at both the 4 and 16 weeks time points. CONCLUSION: Structural changes in salivary gland parenchyma occurred relatively early after IR, whereas the alterations in salivary output were relatively delayed. Further, reductions in salivary flow were not proportional to acinar cell area loss. Together, these findings suggest that nonparenchymal IR damage likely contributes to IR-induced salivary hypofunction.     

鼻咽癌放射性口干症与腮腺受照射体积相关性研究

目的 研究腮腺体积大小与鼻咽癌放射性口干症的关系。方法 选取2015—2016年收治的 199例鼻咽癌患者,根据腮腺大小分为大腮腺组与小腮腺组,并对两组患者放疗后口干情况进行对比,同时对两组之间的剂量学指标进行比较分析。计数资料采用χ²检验,计量资料采用t检验或非参数Mann-Whitney U检验,对DVH指标行非参数Mann-Whitney U检验。结果 两组患者放疗后3、6个月口干程度无差异,放疗后 1年大腮腺组患者口干程度较小腮腺组轻(P=0.035)。两组患者双侧腮腺受量不同,小腮腺组患者双侧腮腺受量高于大腮腺组,而两组患者颌下腺平均受量相近。结论 腮腺初始体积大小是影响放疗后口干评级的因素之一,大腮腺患者放疗后口干恢复情况优于小腮腺患者;对于小腮腺患者在计划制作时应更加注意降低剂量保护腮腺组织。     

Decrease in radio-sensitivity of the tumor by radiation-induced damage to immuno-related cells

Immunological competence plays an important role in response of patients to radiation therapy and dose of radiation required for tumor control depends also on the immunocompetence of the individual patient. Radiation therapy (even localized irradiation) can, however, cause lymphopenia and induce an immunodeficient state. This may facilitate growth of residual tumor cells or metastatic foci, this negating benefits of the therapy. A brief overview of damage to T and B lymphocytes as well as macrophages and natural killer (NK) cells by radiation therapy was presented. The restoration and potentiation of the immunological competence of the patients by biological response modifiers (BRM) such as OK432 (a bacterial preparation), recombinant interferon (rIFN-gamma) and recombinant interleukin-2 (rIL-2) with or without lymphokine activated killer (LAK) cells, were discussed.     

Increase in immunogenicity and sensitivity to natural cell-mediated cytotoxicity following in vitro exposure of MCA105 tumor cells to ultraviolet radiation

The effect of short wave length ultraviolet C (UVC) light irradiation on tumor cell immunogenicity and sensitivity to natural cell-mediated cytotoxicity was studied. Two consecutive courses of UVC irradiation of 3LL Lewis lung carcinoma and MCA105 fibrosarcoma increased their immunogenicity and sensitivity to lysis by normal spleen cells. Analysis of the effector cells involved in lysis of the parental MCA105 and UV-treated MCA105UV tumor cells was performed by comparing the cytotoxic activity of normal spleen cells containing both natural killer (NK) and natural cytotoxicity (NC) cell activity (NK+, NC+) with: (a) normal spleen cells in which NC activity was neutralized by anti-tumor necrosis factor (TNF) antibodies (NK+, NC-); (b) NK-depleted or NK-deficient spleen cells (NK-, NC+); and (c) NK-depleted or -deficient spleen cells with NC activity blocked by anti-TNF antibodies (NK-, NC-). In addition, the ability of polyinosinic-polycytidylic acid or interleukin 2-stimulated spleen cells to lyse UV-treated and untreated tumor cells in the presence or absence of anti-TNF antibodies was also investigated. Lysis of MCA105 cells was shown to be mediated mostly by NC cells, since it was inhibited in the presence of anti-TNF antibodies and was not significantly affected by depletion or stimulation of NK cells. UV irradiation of MCA105 tumor cells substantially increased their sensitivity to both NK and NC effector cells. Augmentation of NK sensitivity of MCA105UV cells was associated with an increase in their lysability by large granular lymphocyte-derived cytolytic granules. UVC treatment of tumor cells also increased their sensitivity to lysis by recombinant TNF-alpha, pointing to the possible mechanism responsible for the increase in their sensitivity to NC cell-mediated cytotoxicity. Indeed, selection of MCA105UV cells for resistance to TNF led to resistance to spleen cell-mediated NC cytotoxicity. UVC irradiation did not affect internalization and degradation of TNF by MCA105UV cells but substantially increased sensitivity to TNF-induced DNA fragmentation. The results of this study indicate that UV irradiation can be a potent and stable modulator of the immunobiological properties of tumor cells.     

Malignant epithelial tumors in the minor salivary glands, the submandibular gland, and the sublingual gland. Prognostic factors and treatment results

Ninety-five malignant tumors in the submandibular gland, the sublingual gland, and the minor salivary glands seen in a 25-year period were reviewed. The patients were retrospectively staged using the Union Internationale Contre le Cancer (UICC) classification. The most frequent tumor was adenoid cystic carcinoma, followed by adenocarcinoma. The submandibular gland was the most frequent location. Five-year and 10-year crude survival rates were 62% and 43%, respectively. Clinical stage was the most important prognostic factor. Survival was not correlated with location of tumor, although recurrence and metastases occurred more frequently in patients with cancer of the submandibular gland. Histologically, the 5-year and 10-year survival was significantly better for patients with adenoid cystic carcinoma compared with the other types; however, although still significant, this difference diminished at 10 years, confirming the need for a long observation time for patients with this tumor.     

Early to late sparing of radiation damage to the parotid gland by adrenergic and muscarinic receptor agonists

Damage to salivary glands after radiotherapeutic treatment of head and neck tumours can severely impair the quality of life of the patients. In the current study we have investigated the early-to-late pathogenesis of the parotid gland after radiation. Also the ability to ameliorate the damage using pretreatment with adrenergic or muscarinic receptor agonists is studied. Rats were locally irradiated with or without i.p. pretreatment with phenylephrine (alpha-adrenoceptor agonist, 5 mg kg(-1)), isoproterenol (beta-adrenoceptor agonist, 5 mg kg(-1)), pilocarpine (4 mg kg(-1)), methacholine (3.75 mg kg(-1)) (muscarinic receptor agonists) or methacholine plus phenylephrine. Parotid salivary flow rate, amylase secretion, the number of cells and gland histology were monitored sequentially up to 240 days postirradiation. The effects were described in 4 distinct phases. The first phase (0-10 days) was characterised by a rapid decline in flow rate without changes in amylase secretion or acinar cell number. The second phase (10-60 days) consists of a decrease in amylase secretion and is paralleled by acinar cell loss. Flow rate, amylase secretion and acinar cell numbers do not change in the third phase (60-120 days). The fourth phase (120-240 days) is determined by a further deterioration of gland function but an increase in acinar cell number, albeit with poor tissue morphology. All drug pretreatments used could reduce radiation effects in phase I and II. The protective effects were lost during phase IV, with the exception of methacholine plus phenylephrine pretreatment. The latter combination of drugs ameliorated radiation-damage throughout the entire follow-up time. The data show that combined pre-irradiation stimulation of muscarinic acetylcholine receptors with methacholine plus alpha-adrenoceptors with phenylephrine can reduce both early and late damage, possibly involving the PLC/PIP2 second messenger pathways. This opens perspectives for the development of clinical applicable methods for long-term sparing of parotid glands subjected to radiotherapy of head and neck cancer patients.     

Dose, volume, and function relationships in parotid salivary glands following conformal and intensity-modulated irradiation of head and neck cancer.

PURPOSE: To determine the relationships between the three-dimensional dose distributions in parotid glands and their saliva production, and to find the doses and irradiated volumes that permit preservation of the salivary flow following irradiation (RT). METHODS AND MATERIALS: Eighty-eight patients with head and neck cancer irradiated with parotid-sparing conformal and multisegmental intensity modulation techniques between March 1994 and August 1997 participated in the study. The mean dose and the partial volumes receiving specified doses were determined for each gland from dose-volume histograms (DVHs). Nonstimulated and stimulated saliva flow rates were selectively measured from each parotid gland before RT and at 1, 3, 6, and 12 months after the completion of RT. The data were fit using a generalized linear model and the normal tissue complication probability (NTCP) model of Lyman-Kutcher. In the latter model, a "severe complication" was defined as salivary flow rate reduced to < or =25% pre-RT flow at 12 months. RESULTS: Saliva flow rates data were available for 152 parotid glands. Glands receiving a mean dose below or equal to a threshold (24 Gy for the unstimulated and 26 Gy for the stimulated saliva) showed substantial preservation of the flow rates following RT and continued to improve over time (to median 76% and 114% of pre-RT for the unstimulated and stimulated flow rates, respectively, at 12 months). In contrast, most glands receiving a mean dose higher than the threshold produced little saliva with no recovery over time. The output was not found to decrease as mean dose increased, as long as the threshold dose was not reached. Similarly, partial volume thresholds were found: 67%, 45%, and 24% gland volumes receiving more than 15 Gy, 30 Gy, and 45 Gy, respectively. The partial volume thresholds correlated highly with the mean dose and did not add significantly to a model predicting the saliva flow rate from the mean dose and the time since RT. The NTCP model parameters were found to be TD50 (the tolerance dose for 50% complications rate for whole organ irradiated uniformly) = 28.4 Gy, n (volume dependence parameter) = 1, and m (the slope of the dose/response relationship) = 0.18. Clinical factors including age, gender, pre-RT surgery, chemotherapy, and certain medical conditions were not found to be significantly associated with the salivary flow rates. Medications (diuretics, antidepressants, and narcotics) were found to adversely affect the unstimulated but not the stimulated flow rates. CONCLUSIONS: Dose/volume/function relationships in the parotid glands are characterized by dose and volume thresholds, steep dose/response relationships when the thresholds are reached, and a maximal volume dependence parameter in the NTCP model. A parotid gland mean dose of < or =26 Gy should be a planning goal if substantial sparing of the gland function is desired.     

Overexpression of BLM promotes DNA damage and increased sensitivity to platinum salts in triple-negative breast and serous ovarian cancers

BackgroundPlatinum-based therapy is an effective treatment for a subset of triple-negative breast cancer and ovarian cancer patients. In order to increase response rate and decrease unnecessary use, robust biomarkers that predict response to therapy are needed.Patients and methodsWe performed an integrated genomic approach combining differential analysis of gene expression and DNA copy number in sensitive compared with resistant triple-negative breast cancers in two independent neoadjuvant cisplatin-treated cohorts. Functional relevance of significant hits was investigated in vitro by overexpression, knockdown and targeted inhibitor treatment.ResultsWe identified two genes, the Bloom helicase (BLM) and Fanconi anemia complementation group I (FANCI), that have both increased DNA copy number and gene expression in the platinum-sensitive cases. Increased level of expression of these two genes was also associated with platinum but not with taxane response in ovarian cancer. As a functional validation, we found that overexpression of BLM promotes DNA damage and induces sensitivity to cisplatin but has no effect on paclitaxel sensitivity.ConclusionsA biomarker based on the expression levels of the BLM and FANCI genes is a potential predictor of platinum sensitivity in triple-negative breast cancer and ovarian cancer.     

p73 protein expression correlates with radiation-induced apoptosis in the lack of p53 response to radiation therapy for cervical cancer

PURPOSE: p73 belongs to the p53 tumor suppressor family of genes and can inhibit cell growth in a p53-like manner by inducing apoptosis or cell cycle arrest. Here, we investigated whether p73 could compensate for impaired p53 function in apoptosis induced by radiation therapy (RT) for cervical cancer. METHODS AND MATERIALS: Sixty-eight patients with squamous cell carcinoma of the cervix who received definitive RT combined with (n=37) or without (n=31) cisplatin were investigated. Biopsy specimens were excised from the cervical tumor before RT and after 9 Gy. RESULTS: Mean apoptosis index (AI) was 0.93% before RT and 1.97% after 9 Gy with a significant increase (p<0.001). For all patients, there was a significant correlation between p73 expression positivity after 9 Gy and AI ratio (AI after 9 Gy/AI before RT) (p=0.021). Forty-one patients were regarded as the p53-responding group according to the expression of p53 after 9 Gy, whereas the remaining 27 patients were regarded as the p53-nonresponding group. A significant correlation between p73 expression after 9 Gy and AI ratio was observed in the p53-non-responding group (p<0.001) but not in the p53-responding group (p=0.940). CONCLUSION: Our results suggest that p73 plays an important role in compensating for the lack of p53 function in radiation-induced apoptosis of cervical cancer.     

The dose to the parotid glands with IMRT for oropharyngeal tumors: the effect of reduction of positioning margins.

PURPOSE: The aim of this paper is to quantify the importance of the reduction of positioning margins applied to the clinical target volume (CTV) on the dose distribution of the parotid gland for different intensity-modulated radiotherapy (IMRT) strategies for the treatment of oropharyngeal cancer. METHODS AND MATERIALS: CTVs and organs at risk were delineated in the planning computed tomographic (CT) scans of three patients. Margins of 0, 3, 6 and 9mm were applied to the CTVs in order to obtain the planning target volumes (PTVs). Three IMRT strategies were used to optimize the dose distribution. RESULTS: The analysis of the three IMRT strategies resulted in: (1) an optimal dose distribution in the PTV; (2) optimal dose distribution in the PTV while sparing the parotid gland and (3) more parotid gland sparing but at expense of the dose homogeneity in the PTV. The mean parotid dose increased linearly with increasing margin by approximately 1.3Gy per mm. As a result, the normal complication probability (NTCP) for xerostomia decreased when smaller margins were applied. Reducing the margin from 6 to 3mm resulted in an NTCP reduction of approximately 20%. CONCLUSION: Reducing the CTV-PTV margin by improving the patient position accuracy may lead to a significant reduction of NTCP for the IMRT treatment of the oropharyngeal tumors and lymph nodes level II.     

Adenoid cystic carcinoma of the salivary glands. Management of recurrent, advanced, or persistent disease with hyperthermia and radiation therapy

Adenoid cystic carcinomas (ACC) of the salivary glands are aggressive tumors characterized by multiple late local recurrences and distant metastases. Current therapy includes wide local excision and high-dose postoperative radiation therapy (XRT) (5400 to 7000 cGy). Despite early aggressive treatment, local recurrence remains a major problem with limited safe and effective therapeutic options available. The excellent local responses obtained in four patients (six sites) with ACC of the head and neck treated either with additional low-dose irradiation (2160 to 3420 cGy) in conjunction with two to five hyperthermia (HT) treatments or with full dose XRT and HT as part of the overall treatment plan are reported. All HT treatments were for 45 minutes once steady state conditions were obtained. Monitored intratumoral temperatures for all treatments achieved average maximum (Tmax), average mean (Tave), and average minimum (Tmin) temperatures of 44.2 degrees C, 41.2 degrees C, and 38.9 degrees C, respectively. A complete response was obtained for all six fields with no significant long-term complications. Two patients remain alive and free of local disease at 42 and 63 months of follow-up. Two patients died--one with metastases (with persistent local control) and one with a local recurrence at 9 and 30 months, respectively, after XRT and HT. This is the first report of HT and low-dose XRT in the management of previously irradiated ACC and suggests a potential role for the use of this modality in the treatment of ACC.     

Comparative sensitivity of cells from human tumors and derivative tumor xenografts to radiation and heat treatments.

BACKGROUND: Human tumor xenografts in athymic mice are often used to study the efficacy of cancer treatments, but it is not known whether the xenografts accurately reflect the treatment responsiveness of the original tumors. PURPOSE: To assess the validity of tumor xenografts as specific models of neoplastic disease, a soft-agar colony assay was used to compare the sensitivity of cells from surgical tumor specimens and derivative xenograft lines to various radiation and heat treatments in vitro. METHODS: Xenograft lines were established from melanomas and from carcinomas of the bladder, breast, cervix, and colon. Single-cell suspensions from the original tumors and the corresponding tumor xenografts were subjected to treatments that measured inherent radiation sensitivity, split-dose radiation repair capacity, low-dose-rate radiation sensitivity, inherent heat sensitivity, capacity for development of thermotolerance, and sensitivity to step-down heating (treatment at 43.5 degrees C followed by treatment at 41.5 degrees C). Cell survival curves were plotted for each treatment, and a two-tailed Student's t test was used to search for statistically significant correlations between the curves. RESULTS: Although cells from different surgical tumor specimens varied widely in their sensitivity to radiation and heat treatments, there was always a statistically significant correlation (P < .05) between the sensitivity of cells from the surgical specimens and the corresponding tumor xenografts. CONCLUSIONS: These observations strongly suggest that intrinsic properties of human tumor cells generally are retained during serial heterotransplantation. Thus, human tumor xenograft lines may be valuable tools in studies aimed at identifying cellular properties of importance for the clinical treatment sensitivity of human cancer. This does not necessarily mean, however, that the treatment responsiveness of the xenografts in vivo mirrors the clinical treatment responsiveness of the tumors in patients.     

Sparing of the submandibular glands by intensity modulated radiotherapy in the treatment of head and neck cancer.

BACKGROUND AND PURPOSE: The submandibular glands produce most of the unstimulated saliva output and are the key in prevention of radiation-related xerostomia. We investigated whether sparing of the submandibular function is feasible with intensity modulated radiotherapy (IMRT). PATIENTS AND METHODS: Thirty-six patients diagnosed with head and neck cancer were treated with IMRT and had at least one parotid gland excluded from the planning target volume. In a subset, of these patients (n=18) where the risk of cancer recurrence in the contralateral submandibular region was judged low, the contralateral submandibular gland was spared from full-dose irradiation. The total unstimulated and stimulated salivary flow rates and adverse effects were monitored. RESULTS: Twelve months following IMRT mean unstimulated saliva flow was 60% of the baseline value among patients who had one submandibular gland spared and 25% among those who did not (P=0.006). Patients whose contralateral submandibular was spared reported less grade two or three xerostomia (4 vs. 11; P=0.018), and used less saliva substitutes. No cancer recurrences were detected at the vicinity of the spared glands during a median follow-up time of 31 months. CONCLUSIONS: Submandibular gland sparing with IMRT is safe in selected patients treated for head and neck cancer. It is effective in prevention of radiation-associated xerostomia.