Tissue reactions to ionizing radiation—Oral mucosa Gruber, Sylvia; Dörr, Wolfgang
Mutation research,
October-December 2016, 2016 Oct - Dec, 2016-10-00, 20161001, Letnik:
770, Številka:
Pt B
Journal Article
Recenzirano
Radiotherapy is one of the most effective treatment strategies for solid malignancies, including head-and-neck tumors (HNT). Oral mucositis is the most frequent, often dose-limiting early adverse ...event of radio(chemo)therapy for HNT. The oral mucosal response is – like that of typical turnover tissues – based on radiation-induced impairment of epithelial proliferation and cell production, in face of ongoing physiological cell differentiation and cell loss, consequently resulting in hypoplasia and eventually mucosal ulceration. The regenerative epithelial response, i.e. repopulation, and hence the impact of overall treatment time, besides intrinsic radiosensitivity, is the dominant parameter of the radiation tolerance of oral mucosa in fractionated radiotherapy protocols.
The epithelial changes are accompanied, at the molecular and cellular level, by various changes in non-epithelial cell populations, i.e. vascular endothelial cells, macrophages, and fibroblasts. An inflammatory response precedes and parallels the epithelial changes; this includes vasodilation associated with rheological consequences and the manifestation of local hypoxia, activation of macrophages and endothelial cells. During these processes, a variety of intra- and intercellular communication pathways are modulated; NF-κB associated signaling is one prominent example. The interactions of these extra-epithelial changes with epithelial hypoplasia, ulceration and regeneration currently remain largely unclear. Research on the molecular mechanisms underlying the clinical manifestation of oral mucositis will allow for identification of potential early biomarkers of oral mucosal morbidity and thus for individualization of patient follow-up and treatment, and also for the development of targeted strategies for prophylaxis and/or mitigation of oral mucositis.
This review summarizes the features of the clinical manifestation of oral mucositis and its consequences, the “classical” radiobiological parameters of mucosal radiation sensitivity. It moreover focuses on the underlying “molecular” mechanisms, and on biology-based approaches for the amelioration of radiation-induced oral mucositis.
Abstract Background and purpose Currently, there is no consensus on dose prescription in image guided adaptive brachytherapy (IGABT) in locally advanced cervical cancer. The purpose of this study was ...to provide evidence based recommendations for tumor dose prescription based on results from a multi-center patient series (retroEMBRACE). Materials and methods This study analyzed 488 locally advanced cervical cancer patients treated with external beam radiotherapy ± chemotherapy combined with IGABT. Brachytherapy contouring and reporting was according to ICRU/GEC-ESTRO recommendations. The Cox Proportional Hazards model was applied to analyze the effect on local control of dose-volume metrics as well as overall treatment time (OTT), dose rate, chemotherapy, and tumor histology. Results With a median follow up of 46 months, 43 local failures were observed. Dose (D90) to the High Risk Clinical Target Volume (CTVHR ) ( p = 0.022, HR = 0.967 per Gy) was significant for local control, whereas increasing CTVHR volume ( p = 0.004, HR = 1.017 per cm3 ), and longer OTT ( p = 0.004, HR = 1.023 per day) were associated with worse local control. Histology ( p = 0.084), chemotherapy ( p = 0.49) and dose rate ( p = 1.00) did not have significant impact on local control. Separate analyses according to stage of disease showed that dose to CTVHR , residual gross tumor volume (GTVres ), and Intermediate Risk CTV (CTVIR ) has significant impact on local control. Conclusion CTVHR dose of ⩾85 Gy (D90) delivered in 7 weeks provides 3-year local control rates of >94% in limited size CTVHR (20 cm3 ), >93% in intermediate size (30 cm3 ) and >86% in large size (70 cm3 ) CTVHR . CTVIR and GTVres dose of ⩾60 Gy and ⩾95 Gy (D98) leads to similar local control. A dose of 5 Gy (CTVHR ) is required to compensate an increase of OTT by one week. Increased CTVHR volume by 10 cm3 requires additional 5 Gy for equivalent local control.
To evaluate the predictive value of dose-volume histogram (DVH) parameters for late side effects of the rectum, sigmoid colon, and bladder in image-guided brachytherapy for cervix cancer patients.
A ...total of 141 patients received external-beam radiotherapy and image-guided brachytherapy with or without chemotherapy. The DVH parameters for the most exposed 2, 1, and 0.1 cm(3) (D(2cc), D(1cc), and D(0.1cc)) of the rectum, sigmoid, and bladder, as well as International Commission on Radiation Units and Measurements point doses (D(ICRU)) were computed. Total doses were converted to equivalent doses in 2 Gy by applying the linear-quadratic model (α/β = 3 Gy). Late side effects were prospectively assessed using the Late Effects in Normal Tissues-Subjective, Objective, Management and Analytic score. The following patient groups were defined: Group 1: no side effects (Grade 0); Group 2: side effects (Grade 1-4); Group 3: minor side effects (Grade 0-1); and Group 4: major side effects (Grade 2-4).
The median follow-up was 51 months. The overall 5-year actuarial side effect rates were 12% for rectum, 3% for sigmoid, and 23% for bladder. The mean total D(2cc) were 65 ± 12 Gy for rectum, 62 ± 12 Gy for sigmoid, and 95 ± 22 Gy for bladder. For rectum, statistically significant differences were observed between Groups 1 and 2 in all DVH parameters and D(ICRU). Between Groups 3 and 4, no difference was observed for D(0.1cc). For sigmoid, significant differences were observed for D(2cc) and D(1cc), but not for D(0.1cc) in all groups. For bladder, significant differences were observed for all DVH parameters only comparing Groups 3 and 4. No differences were observed for D(ICRU).
The parameters D(2cc) and D(1cc) have a good predictive value for rectal toxicity. For sigmoid, no prediction could be postulated because of limited data. In bladder, DVH parameters were predictive only for major toxicity.
Brachytherapy in the treatment of locally advanced cervical cancer has changed substantially because of the introduction of combined intracavitary/interstitial applicators and an adaptive target ...concept, which is the focus of the prospective, multi-institutional EMBRACE study (www.embracestudy.dk) on image-guided adaptive brachytherapy (IGABT). So far, little has been reported about the development of early to late vaginal morbidity in the frame of IGABT. Therefore, the aim of the present EMBRACE analysis was to evaluate the manifestation pattern of vaginal morbidity during the first 2 years of follow-up.
In total, 588 patients with a median follow-up time of 15 months and information on vaginal morbidity were included. Morbidity was prospectively assessed at baseline, every 3 months during the first year, and every 6 months in the second year according to the Common Terminology Criteria for Adverse Events, version 3, regarding vaginal stenosis, dryness, mucositis, bleeding, fistula, and other symptoms. Crude incidence rates, actuarial probabilities, and prevalence rates were analyzed.
At 2 years, the actuarial probability of severe vaginal morbidity (grade ≥3) was 3.6%. However, mild and moderate vaginal symptoms were still pronounced (grade ≥1, 89%; grade ≥2, 29%), of which the majority developed within 6 months. Stenosis was most frequently observed, followed by vaginal dryness. Vaginal bleeding and mucositis were mainly mild and infrequently reported.
Severe vaginal morbidity within the first 2 years after definitive radiation (chemo)therapy including IGABT with intracavitary/interstitial techniques for locally advanced cervical cancer is limited and is significantly less than has been reported from earlier studies. Thus, the new adaptive target concept seems to be a safe treatment with regard to the vagina being an organ at risk. However, mild to moderate vaginal morbidity is still pronounced with currently applied IGABT, and it needs further attention.
To establish dose-response relationships for late side effects of the rectum and bladder in cervix cancer patients after magnetic resonance image-guided adaptive brachytherapy (IGABT).
A cohort of ...141 patients was treated with 45 to 50.4 Gy with or without cisplatin plus 4 fractions of 7 Gy IGABT. Doses for the most exposed 2, 1, and 0.1-cm(3) (D(2 cc), D(1 cc), D(0.1 cc)) volumes of the rectum and bladder were converted into the equivalent dose in 2 Gy fractions (EQD2), using a linear quadratic model (α/β = 3 Gy). Late side effects were prospectively assessed (using late effects in normal tissues subjective, objective, management and analytic LENT SOMA) scales. Dose-response relationships were determined by logit analyses.
Eleven patients developed rectal side effects, and 23 patients had urinary side effects. A significant dose effect was found for all rectal dose-volume histogram (DVH) parameters for patients with side effect grades of 1 to 4 but was only significant for D(2 cc) and D(1 cc) for grades ≥ 2. The ED10 values for D(2 cc) were 73 Gy for grades 1 to 4 and 78 Gy for grades 2 to 4 rectal morbidity. For bladder side effects, a significant dose effect was shown for all DVH parameters for complication grades ≥ 2; the respective ED10 was 101 Gy.
Well-defined dose-response curves could be established for D(2 cc) in the rectum and the urinary bladder.
Radiation therapy treatment of breast cancer, Hodgkin's disease or childhood cancers expose the heart to high local radiation doses, causing an increased risk of cardiovascular disease in the ...survivors decades after the treatment. The mechanisms that underlie the radiation damage remain poorly understood so far. Previous data show that impairment of mitochondrial oxidative metabolism is directly linked to the development of cardiovascular disease.
In this study, the radiation-induced in vivo effects on cardiac mitochondrial proteome and function were investigated. C57BL/6N mice were exposed to local irradiation of the heart with doses of 0.2 Gy or 2 Gy (X-ray, 200 kV) at the age of eight weeks, the control mice were sham-irradiated. After four weeks the cardiac mitochondria were isolated and tested for proteomic and functional alterations. Two complementary proteomics approaches using both peptide and protein quantification strategies showed radiation-induced deregulation of 25 proteins in total. Three main biological categories were affected: the oxidative phophorylation, the pyruvate metabolism, and the cytoskeletal structure. The mitochondria exposed to high-dose irradiation showed functional impairment reflected as partial deactivation of Complex I (32%) and Complex III (11%), decreased succinate-driven respiratory capacity (13%), increased level of reactive oxygen species and enhanced oxidation of mitochondrial proteins. The changes in the pyruvate metabolism and structural proteins were seen with both low and high radiation doses.
This is the first study showing the biological alterations in the murine heart mitochondria several weeks after the exposure to low- and high-dose of ionizing radiation. Our results show that doses, equivalent to a single dose in radiotherapy, cause long-lasting changes in mitochondrial oxidative metabolism and mitochondria-associated cytoskeleton. This prompts us to propose that these first pathological changes lead to an increased risk of cardiovascular disease after radiation exposure.
This study analyzed functioning and symptom scores for longitudinal quality of life (QoL) from patients with locally advanced cervical cancer who underwent definitive chemoradiation therapy with ...image guided adaptive brachytherapy in the EMBRACE study.
In total, 744 patients at a median follow-up of 21 months were included. QoL was prospectively assessed using European Organization for Research and Treatment of Cancer Quality of Life core module 30 (EORTC QLQ-C30) and EORTC cervical cancer module 24 (CX24) questionnaires at baseline, then every 3 months during the first year, every 6 months in the second and third years, and finally yearly thereafter in patients with no evidence of disease. Outcomes were evaluated over time and compared to those from an age-matched female reference population.
General QoL and emotional and social functioning were impaired at baseline but improved during the first 6 months after treatment, to reach a level comparable to that of the reference population, whereas cognitive functioning remained impaired. Both social and role functioning showed the lowest scores at baseline but which increased after treatment to reach a plateau at 6 months and then declined slightly at 3 and 4 years. The overall symptom experience was elevated at baseline and decreased to a level within the range of that of the reference population. Similarly, tumor-related symptoms (eg, pain, appetite loss, and constipation), which were present before treatment, decreased substantially at the first follow-up after treatment. Several treatment-related symptoms developed either immediately after and persisted over time (diarrhea, menopausal symptoms, peripheral neuropathy, and sexual functioning problems) or developed gradually after treatment (lymphedema and dyspnea).
This longitudinal prospective QoL analysis showed that patients' general QoL and functioning were impaired before treatment compared to those of reference data. Several tumor-related symptoms resolved after treatment, and functioning and general QoL returned to that of the level of the reference population, indicating a transient impact of diagnosis and treatment. However, several treatment-related symptoms and problems did develop and persist, either immediately or gradually after treatment.
To investigate the value of dose-volume histogram (DVH) parameters for predicting local control in magnetic resonance (MR) image-guided brachytherapy (IGBT) for patients with cervical cancer.
Our ...study population consists of 141 patients with cervical cancer (Stages IB-IVA) treated with 45-50 Gy external beam radiotherapy plus four times 7 Gy IGBT with or without cisplatin. Gross tumor volume (GTV), high-risk clinical target volume (HRCTV), and intermediate-risk clinical target volume (IRCTV) were contoured, and DVH parameters (minimum dose delivered to 90% of the volume of interest D90 and D100) were assessed. Doses were converted to the equivalent dose in 2 Gy (EQD2) by applying the linear quadratic model (alpha/beta = 10 Gy). Groups were defined for patients with or without local recurrence (LR) in the true pelvis for tumor size at diagnosis (GTV at diagnosis GTVD of 2-5 cm (Group 1) or greater than 5 cm (Group 2) and for tumor size response at IGBT (HRCTV) of 2-5 cm (Group 2a) or greater than 5 cm (Group 2b).
Eighteen LRs were observed. The most important DVH parameters correlated with LR were the D90 and D100 for HRCTV. Mean D90 and D100 values for HRCTV were 86 +/- 16 and 65 +/- 10 Gy, respectively. The D90 for HRCTV greater than 87 Gy resulted in an LR incidence of 4% (3 of 68) compared with 20% (15 of 73) for D90 less than 87 Gy. The effect was most pronounced in the tumor group (Group 2b).
We showed an increase in local control in IGBT in patients with cervical cancer with the dose delivered, which can be expressed by the D90 and D100 for HRCTV. Local control rates greater than 95% can be achieved if the D90 (EQD2) for HRCTV is 87 Gy or greater.
Purpose
A relative biological effectiveness (RBE) of 1.1 is commonly used in clinical proton therapy, irrespective of tissue type and depth. This in vitro study was conducted to quantify the RBE of ...scanned protons as a function of the dose‐averaged linear energy transfer (LETd) and the sensitivity factor (α/ß)X. Additionally, three phenomenological models (McNamara, Rørvik, and Jones) and one mechanistic model (repair‐misrepair‐fixation, RMF) were applied to the experimentally derived data.
Methods
Four human cell lines (FaDu, HaCat, Du145, SKMel) with differential (α/ß)X ratios were irradiated in a custom‐designed irradiation setup with doses between 0 and 6 Gy at proximal, central, and distal positions of a 80 mm spread‐out Bragg peak (SOBP) centered at 80 mm (setup A: proton energies 66.5–135.6 MeV) and 155 mm (setup B: proton energies 127.2–185.9 MeV) depth, respectively. LETd values at the respective cell positions were derived from Monte Carlo simulations performed with the treatment planning system (TPS, RayStation). Dosimetric measurements were conducted to verify dose homogeneity and dose delivery accuracy. RBE values were derived for doses that resulted in 90 % (RBE90) and 10 % (RBE10) of cell survival, and survival after a 0.5 Gy dose (RBE0.5Gy), 2 Gy dose (RBE2Gy), and 6 Gy dose (RBE6Gy).
Results
LETd values at sample positions were 1.9, 2.1, 2.5, 2.8, 4.1, and 4.5 keV/µm. For the cell lines with high (α/ß)X ratios (FaDu, HaCat), the LETd did not impact on the RBE. For low (α/ß)X cell lines (Du145, SKMel), LQ‐derived survival curves indicated a clear correlation of LETd and RBE. RBE90 values up to 2.9 and RBE10 values between 1.4 and 1.8 were obtained. Model‐derived RBE predictions slightly overestimated the RBE for the high (α/ß)X cell lines, although all models except the Jones model provided RBE values within the experimental uncertainty. For low (α/ß)X cell lines, no agreement was found between experiments and model predictions, that is, all models underestimated the measured RBE.
Conclusions
The sensitivity parameter (α/ß)X was observed to be a major influencing factor for the RBE of protons and its sensitivity toward LETd changes. RBE prediction models are applicable for high (α/ß)X cell lines but do not estimate RBE values with sufficient accuracy in low (α/ß)X cell lines.
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