Radiation fibrosis of the vocal fold: from man to mouse

Radiation-Induced Fibrosis in Head and Neck Cancer: Challenges and Future Therapeutic Strategies for Vocal Fold Treatments

Head and neck cancer encompasses a diverse group of malignant neoplasms originating in regions such as the oral cavity, oropharynx, hypopharynx, larynx, sinonasal cavities, and salivary glands. HNC represents a significant public health challenge, and recent reports indicate an increment in the incidence of HNC in young adults. In 2020, approximately 377,700 new HNC cases and 177,800 HNC-related deaths were reported globally. Major risk factors include tobacco smoking, alcohol consumption, and human papillomavirus (HPV) infections. HNC impacts vital functions such as breathing, swallowing, and speech. Treatments for this type of cancer within this complex anatomy include surgery, radiotherapy, and chemotherapy combinations. Radiotherapy is often an essential component of both curative and palliative HNC treatment, balancing tumor control with the preservation of function and appearance. However, its use can damage adjacent normal tissues, causing acute or chronic toxicity. One complication of HNC irradiation is VF fibrosis, which leads to severe voice impairments, significantly affecting patients' quality of life. Fibrosis involves excessive and aberrant deposition of extracellular matrix, driven by factors such as TGF-β1 and inflammatory cytokines, which ultimately impair the flexibility and function of VF. Current radiation-induced fibrosis treatments primarily focus on symptom management and include systemic therapies like corticosteroids, anti-inflammatory drugs, and antioxidants. However, these treatments have limited efficacy. Experimental approaches targeting molecular pathways involved in fibrosis are being explored. Given the limitations of these treatments, advancing research is crucial to develop more effective therapeutic strategies that can significantly improve the quality of life for HNC patients, especially those vulnerable to VF fibrosis.

Swallowing-related muscle inflammation and fibrosis induced by a single dose of radiation exposure in mice

BACKGROUND

Although radiotherapy is commonly used to treat head and neck cancer, it may lead to radiation-associated dysphagia (RAD). There are various causes of RAD, however, the mechanism has not yet been fully identified. Currently, the only effective treatment for RAD is rehabilitation. Additionally, there are few available animal models of RAD, necessitating the development of new models to establish and evaluate RAD treatments. We hypothesize that radiation-induced neck muscle fibrosis could be one of the causes of RAD due to impairment of laryngeal elevation. Therefore, in this study, we focused on the changes in inflammation and fibrosis of the strap muscles (Sternohyoid, Sternothyroid, and Thyrohyoid muscles) after a single-dose irradiation. This research aims to provide a reference animal model for future studies on RAD.

RESULTS

Compared to control mice, those treated with 72-Gy, but not 24-Gy, irradiation had significantly increased tumor necrosis factor-α (TNF-α) (p < 0.01) and α-smooth muscle actin (αSMA) (p < 0.05) expression at 10 days and significantly increased expression levels of motif chemokine ligand-2 (CCL2), α-SMA, tumor growth factor-β1 (TGF-β1), type1 collagen, and interleukin-1β (IL-1β) (p < 0.05) in the muscles at 1 month by real-time PCR analysis. The results of immunohistochemistry showed that the deposition of type 1 collagen gradually increased in extracellular space after radiation exposure, and the positive area was significantly increased at 3 months compared to non-irradiated control.

CONCLUSIONS

A single dose of 72-Gy irradiation induced significant inflammation and fibrosis in the strap muscles of mice at 1 month, with immunohistochemical changes becoming evident at 3 months. This cervical irradiation-induced fibrosis model holds potential for establishing an animal model for RAD in future studies.

LEVEL OF EVIDENCE

N/A.

Hypoxia Modulates Radiosensitivity and Response to Different Radiation Qualities in A549 Non-Small Cell Lung Cancer (NSCLC) Cells

Hypoxia-induced radioresistance reduces the efficacy of radiotherapy for solid malignancies, including non-small cell lung cancer (NSCLC). Cellular hypoxia can confer radioresistance through cellular and tumor micro-environment adaptations. Until recently, studies evaluating radioresistance secondary to hypoxia were designed to maintain cellular hypoxia only before and during irradiation, while any handling of post-irradiated cells was carried out in standard oxic conditions due to the unavailability of hypoxia workstations. This limited the possibility of simulating in vivo or clinical conditions in vitro. The presence of molecular oxygen is more important for the radiotoxicity of low-linear energy transfer (LET) radiation (e.g., X-rays) than that of high-LET carbon (12C) ions. The mechanisms responsible for 12C ions' potential to overcome hypoxia-induced radioresistance are currently not fully understood. Therefore, the radioresistance of hypoxic A549 NSCLC cells following exposure to X-rays or 12C ions was investigated along with cell cycle progression and gene expression by maintaining hypoxia before, during and after irradiation. A549 cells were incubated under normoxia (20% O2) or hypoxia (1% O2) for 48 h and then irradiated with X-rays (200 kV) or 12C ions (35 MeV/n, LET ~75 keV/µm). Cell survival was evaluated using colony-forming ability (CFA) assays immediately or 24 h after irradiation (late plating). DNA double-strand breaks (DSBs) were analyzed using γH2AX immunofluorescence microscopy. Cell cycle progression was determined by flow cytometry of 4',6-diamidino-2-phenylindole-stained cells. The global transcription profile post-irradiation was evaluated by RNA sequencing. When hypoxia was maintained before, during and after irradiation, hypoxia-induced radioresistance was observed only in late plating CFA experiments. The killing efficiency of 12C ions was much higher than that of X-rays. Cell survival under hypoxia was affected more strongly by the timepoint of plating in the case of X-rays compared to 12C ions. Cell cycle arrest following irradiation under hypoxia was less pronounced but more prolonged. DSB induction and resolution following irradiation were not significantly different under normoxia and hypoxia. Gene expression response to irradiation primarily comprised cell cycle regulation for both radiation qualities and oxygen conditions. Several PI3K target genes involved in cell migration and cell motility were differentially upregulated in hypoxic cells. Hypoxia-induced radioresistance may be linked to altered cell cycle response to irradiation and PI3K-mediated changes in cell motility and migration in A549 cells rather than less DNA damage or faster repair.

Matrix Metalloproteinases and Their Inhibitors as Potential Prognostic Biomarkers in Head and Neck Cancer after Radiotherapy

Head and neck cancer (HNC) is among the ten most frequent tumours, with 5-year survival rates varying from 30% to 70% depending on the stage and location of the tumour. HNC is traditionally known as head and neck squamous cell carcinoma (HNSCC), since 90% arises from epithelial cells. Metastasis remains a major cause of mortality in patients with HNSCC. HNSCC patients with metastatic disease have an extremely poor prognosis with a survival rate of less than a year. Matrix metalloproteinases (MMPs) have been described as biomarkers that promote cell migration and invasion. Radiotherapy is widely used to treat HNSCC, being a determining factor in the alteration of the tumour's biology and microenvironment. This review focuses on analysing the current state of the scientific literature on this topic. Although few studies have focused on the role of these proteinases in HNC, some authors have concluded that radiotherapy alters the behaviour of MMPs and tissue inhibitors of metalloproteinases (TIMPs). Therefore, more research is needed to understand the roles played by MMPs and their inhibitors (TIMPs) as prognostic biomarkers in patients with HNC and their involvement in the response to radiotherapy.

Efficacy of Voice Therapy in Rehabilitation of Muscle Tension Dysphonia in Patients of Nonlaryngeal Head and Neck Cancer: A Sequelae of Chemoradiotherapy

The association of voice disorders in laryngeal cancers has been studied extensively; however Dysphonia associated with chemo-radiation in non laryngeal Head and Neck cancer (HNC) is a new area of practice in voice clinics. This study thus aimed to evaluate the efficacy of voice rehabilitation among non-laryngeal HNC survivors who were treated with curative RadioTherapy (RT)/Chemoradiotherapy (CRT) in adjunct with or without surgery. This tertiary institutional assessor blinded quasi experimental study after inclusion and exclusion criteria consisted of a study cohort of 128 patients who within 1-3 months of completion of treatment for HNC reported to the laryngology clinic for voice complaints and throat discomfort. All patients underwent documentation of laryngeal endoscopic imaging, acoustics assessment, Aronson's Laryngeal Palpatory Method (LPM) and Voice Handicap Index (VHI). Thereafter they were subjected to Vocal Rehabilitation Therapy (VRT) which constituted of Manual circumlaryngeal therapy, SOVTE, and vocal hygiene program. Re-evaluation of the vocal parameters was done at 6 weeks and 3 months from the start of the VRT. All parameters were significantly altered at 6 weeks and 3 months follow-up. Post VRT the videolaryngoscopic findings showed reduction in abnormal supraglottic MTPs with subsequent good approximation of true cords and reduction of involvement of supralaryngeal activities. The Dysphonia Severity Index (DSI) impairment levels and VHI scores showed significant improvement from the baseline to both at 6 weeks and 3 months of VRT (p < 0.001). DSI and VHI scores even showed significant improvement between 6 weeks to 3 months of therapy. There was highly significant correlation of VRT with/without surgery, with CRT and in non-smokers at 6 weeks and 3 months of VRT. In non-laryngeal head and neck malignancies, VRT offered as early as within 1-3 months of completion of treatment of HNC ameliorates surgical and chemo-radiation induced Muscle Tension Dysphonia.

Late laryngeal dysfunction in head and neck cancer survivors

Objectives

Head and neck cancer (HNC) survivorship issues are areas of increasing research interest. Laryngeal dysfunction in HNC patients is particularly important given the importance of the larynx in voice, swallowing, and airway protection. The objective of our study is to characterize late laryngeal dysfunction in a cohort of long-term HNC survivors.

Methods

HNC survivors who were at least 2 years post-treatment were recruited prospectively for standard collection of videolaryngoscopy findings, videofluoroscopic swallowing studies, and assessment of clinical outcomes. Descriptive statistics were performed and clinical presentation and outcomes were compared between survivors >10 years and <10 years post-treatment. Additional factor analysis to correlate clinical outcomes with clinical variables was performed.

Results

Thirty participants were analyzed with a mean age of 66 years. The majority were male (80%) patients treated for oropharyngeal squamous cell carcinoma (67%). Within the cohort, 43% underwent primary chemoradiation therapy and had 13% radiation alone. Common presenting symptoms included swallowing dysfunction (83%), voice change (67%), and chronic cough (17%). Laryngeal findings on video laryngoscopy include vocal fold motion abnormalities (VFMA) in over half of participants (61%) and mucosal changes in 20%. A weak correlation was found between time since treatment and laryngeal dysfunction (r = .182, p = .34), and no correlation was found between age, sex, time since treatment, or primary site and the presence or absence of VFMA, G-tube status, or tracheostomy-tube status.

Conclusion

Late laryngeal dysfunction in HNC survivors contributes to significant morbidity, is difficult to treat, and remains static decades after treatment for their original cancer.

Lay Summary

The voice-box, or the larynx, plays an important role in voice, swallowing and airway protection. It is particularly vulnerable to radiation-related damage and changes. This study demonstrates the sequelae of long-term damage of the larynx in head and cancer survivors.

Level of Evidence

IV.

The Histological Background of Recurrence in Laryngeal Squamous Cell Carcinoma: An Insight into the Modifications of Tumor Microenvironment

Recurrent laryngeal carcinoma presents differences from the primary tumor that largely depend on the treatment. In this article, we review the histologic and molecular treatment-induced changes that may affect the diagnosis of recurrent laryngeal carcinoma, the assessment of predictive markers, and the response to treatment with immune checkpoint inhibitors. Radiotherapy induces profound modifications that are strictly related to necrosis of different tissue components, fibrosis, and damage of the tumor vessels. Postradiotherapy recurrent/persistent laryngeal squamous cell carcinoma typically presents a discohesive growth pattern within a fibrotic background associated with significant changes of the tumor immune microenvironment, with both important immunosuppressive and immunostimulatory effects. Overall, the increase of immunoregulatory cells and immune checkpoints such as CTLA-4, TIM-3, PD-1, and PD-L1 induced by radiotherapy and chemotherapy strongly supports the use of immune checkpoint inhibitors in recurrent/persistent laryngeal carcinoma. Future studies aiming to identify predictive factors of the response to immune checkpoint inhibitors should consider such treatment-induced modifications.

Voice After Cordectomy Type I or Type II or Radiation Therapy for Large T1a Glottic Cancer

OBJECTIVE

T_1a glottic cancer can be treated with transoral laser microsurgery (TLM) or radiation therapy (RT). Dysphonia is the major disadvantage of TLM, and preservation of voice appears to be the best advantage of RT compared to TLM. Studies on voice outcomes of both options gave conflicting results, but there is a tendency toward better voice outcome after TLM compared to the past.

STUDY DESIGN

Nonrandomized retrospective cohort study.

SETTING

Tertiary referral center.

METHODS

In total, 172 patients with a cancer lesion involving more than two-thirds of 1 membranous vocal fold underwent cordectomy type I (n = 56) (C1 group) or type II (n = 59) (C2 group) or RT (n = 57) (RT group). GRBASI (grade, roughness, breathiness, asthenia, strain, instability), videolaryngostroboscopy, Voice Handicap Index-30, acoustic analysis including F0, jitter, shimmer, noise to harmonic ratio, cepstral peak prominence, and cepstral spectral index of dysphonia using running speech, and aerodynamic analysis were performed before treatment and 6 and 24 months after treatment.

RESULTS

Study groups did not differ significantly on pretreatment voice outcomes (P > .05). The RT group had significantly better voice outcomes at 6 months posttreatment compared to the C1 and C2 groups (P < .05). The C1 group had significantly better voice outcomes at 6 months posttreatment compared to the C2 group (P < .05). The C1 group had significantly better voice outcomes at 24 months posttreatment compared to the RT and C2 groups (P < .05). The RT and C2 groups did not differ significantly at 24 months posttreatment (P > .05).

CONCLUSION

Voice outcomes after C2 are equal to RT. C1 has better voice outcomes than RT. C1 and C2 can be the treatment of choice for large T_1a glottic cancers.

Laryngeal contact granuloma after radiotherapy in patients with nasopharyngeal carcinoma: a case series

Background

Laryngeal contact granuloma (LCG) is a benign hypertrophic lesion and phonatory injury after abnormal vocal behavior is regarded as its major etiology. Patients receiving radiation for non-laryngeal head and neck tumors are troubled by persistent voice impairment. The occurrence of LCG after radiotherapy for nasopharyngeal carcinoma (NPC) in our practice has implored us to re-exam their underlying etiology. We hypothesize that a proportion of LCG results from voice change caused by non-laryngeal head and neck cancer radiotherapy and firstly describe a distinct LCG population originated after radiotherapy for NPC with respect to the clinical profile, presentation, prognosis and response to treatment of patients.

Methods

We retrospectively reviewed the laryngoscopic examination and tumor study findings to elucidate the common clinical features of patients who presented with LCG after radiotherapy for NPC. All patients were regularly monitored with telescopic examination until lesions disappeared. Data on age, sex, clinical presentation, telescopic findings, management, latency time of lesion formation, remission time and clinical outcome were reviewed.

Results

The medical review identified 27 cases of LCG secondary to radiotherapy for NPC. All lesions had been diagnosed during routine endoscopy following radiation. The interval between radiation onset and endoscopic diagnosis was 3.77 months (range, 0.67-11 months). 20 cases were resolved through simple observation, 4 cases were resolved with the administration of proton pump inhibitors (PPIs), and 3 cases with a poor response to PPI therapy required subsequent surgical resection. The mean remission time in the observation and PPI groups was 4.42 months (range, 0.73-18.9 months) and 5.78 months (range, 2.17-14.63 months), respectively. All patients recovered completely and none experienced recurrence during a mean follow-up of 32.44 months (range, 5.6-71.67 months).

Conclusions

Iatrogenic granulomas of vocal process are presenting after radiation for non-laryngeal head and neck cancers. In contrast with spontaneous granulomas, these granulomas can be cured at high remission rates and low recurrence trend without specific intervention. Thus, simple observation may be sufficient for radiation-induced LCG.

Matrix Adhesiveness Regulates Myofibroblast Differentiation from Vocal Fold Fibroblasts in a Bio-orthogonally Cross-linked Hydrogel

Repeated mechanical and chemical insults cause an irreversible alteration of extracellular matrix (ECM) composition and properties, giving rise to vocal fold scarring that is refractory to treatment. Although it is well known that fibroblast activation to myofibroblast is the key to the development of the pathology, the lack of a physiologically relevant in vitro model of vocal folds impedes mechanistic investigations on how ECM cues promote myofibroblast differentiation. Herein, we describe a bio-orthogonally cross-linked hydrogel platform that recapitulates the alteration of matrix adhesiveness due to enhanced fibronectin deposition when vocal fold wound healing is initiated. The synthetic ECM (sECM) was established via the cycloaddition reaction of tetrazine (Tz) with slow (norbornene, Nb)- and fast (trans-cyclooctene, TCO)-reacting dienophiles. The relatively slow Tz-Nb ligation allowed the establishment of the covalent hydrogel network for 3D cell encapsulation, while the rapid and efficient Tz-TCO reaction enabled precise conjugation of the cell-adhesive RGDSP peptide in the hydrogel network. To mimic the dynamic changes of ECM composition during wound healing, RGDSP was conjugated to cell-laden hydrogel constructs via a diffusion-controlled bioorthognal ligation method 3 days post encapsulation. At a low RGDSP concentration (0.2 mM), fibroblasts residing in the hydrogel remained quiescent when maintained in transforming growth factor beta 1 (TGF-β1)-conditioned media. However, at a high concentration (2 mM), RGDSP potentiated TGF-β1-induced myofibroblast differentiation, as evidenced by the formation of an actin cytoskeleton network, including F-actin and alpha-smooth muscle actin. The RGDSP-driven fibroblast activation to myofibroblast was accompanied with an increase in the expression of wound healing-related genes, the secretion of profibrotic cytokines, and matrix contraction required for tissue remodeling. This work represents the first step toward the establishment of a 3D hydrogel-based cellular model for studying myofibroblast differentiation in a defined niche associated with vocal fold scarring.

Photobiomodulation therapy in management of cancer therapy-induced side effects: WALT position paper 2022

Disclaimer

This article is based on recommendations from the 12th WALT Congress, Nice, October 3-6, 2018, and a follow-up review of the existing data and the clinical observations of an international multidisciplinary panel of clinicians and researchers with expertise in the area of supportive care in cancer and/or PBM clinical application and dosimetry. This article is informational in nature. As with all clinical materials, this paper should be used with a clear understanding that continued research and practice could result in new insights and recommendations. The review reflects the collective opinion and, as such, does not necessarily represent the opinion of any individual author. In no event shall the authors be liable for any decision made or action taken in reliance on the proposed protocols.

Objective

This position paper reviews the potential prophylactic and therapeutic effects of photobiomodulation (PBM) on side effects of cancer therapy, including chemotherapy (CT), radiation therapy (RT), and hematopoietic stem cell transplantation (HSCT).

Background

There is a considerable body of evidence supporting the efficacy of PBM for preventing oral mucositis (OM) in patients undergoing RT for head and neck cancer (HNC), CT, or HSCT. This could enhance patients’ quality of life, adherence to the prescribed cancer therapy, and treatment outcomes while reducing the cost of cancer care.

Methods

A literature review on PBM effectiveness and dosimetry considerations for managing certain complications of cancer therapy were conducted. A systematic review was conducted when numerous randomized controlled trials were available. Results were presented and discussed at an international consensus meeting at the World Association of photobiomoduLation Therapy (WALT) meeting in 2018 that included world expert oncologists, radiation oncologists, oral oncologists, and oral medicine professionals, physicists, engineers, and oncology researchers. The potential mechanism of action of PBM and evidence of PBM efficacy through reported outcomes for individual indications were assessed.

Results

There is a large body of evidence demonstrating the efficacy of PBM for preventing OM in certain cancer patient populations, as recently outlined by the Multinational Association for Supportive Care in Cancer/International Society of Oral Oncology (MASCC/ISOO). Building on these, the WALT group outlines evidence and prescribed PBM treatment parameters for prophylactic and therapeutic use in supportive care for radiodermatitis, dysphagia, xerostomia, dysgeusia, trismus, mucosal and bone necrosis, lymphedema, hand-foot syndrome, alopecia, oral and dermatologic chronic graft-versus-host disease, voice/speech alterations, peripheral neuropathy, and late fibrosis amongst cancer survivors.

Conclusions

There is robust evidence for using PBM to prevent and treat a broad range of complications in cancer care. Specific clinical practice guidelines or evidence-based expert consensus recommendations are provided. These recommendations are aimed at improving the clinical utilization of PBM therapy in supportive cancer care and promoting research in this field. It is anticipated these guidelines will be revised periodically.

Change in Voice Quality after Radiotherapy for Early Glottic Cancer

Our aim was to track the changes in voice quality for two years after radiotherapy (RT) for early glottic cancer. A videoendostroboscopy, subjective patient and phoniatrician voice assessments, a Voice Handicap Index questionnaire, and objective acoustic measurements (F0, jitter, shimmer, maximal phonation time) were performed on 50 patients with T1 glottic carcinomas at 3, 12, and 24 months post-RT. The results were compared between the subsequent assessments, and between the assessments at 3 months and 24 months post-RT. The stroboscopy showed a gradual progression of fibrosis of the vocal folds with a significant difference apparent when the assessments at 3 months and 24 months were compared (p < 0.001). Almost all of the subjective assessments of voice quality showed an improvement during the first 2 years, but significant differences were noted at 24 months. Jitter and shimmer deteriorated in the first year after RT with a significant deterioration noticed between the sixth and twelfth months (p = 0.048 and p = 0.002, respectively). Two years after RT, only 8/50 (16%) patients had normal voices. The main reasons for a decreased voice quality after RT for early glottic cancer were post-RT changes in the larynx. Despite a significant improvement in the voice after RT shown in a few of the evaluation methods, only a minority of the patients had a normal voice two years post-RT.

Effect of vocal rehabilitation after chemoradiation for non-laryngeal head and neck cancers

Objective

This study evaluated the effect of voice intervention in patients who received chemoradiation to the neck for non-laryngeal head and neck malignancies.

Methods

Twenty individuals with non-laryngeal malignancies of the head and neck who received chemoradiation were divided by block randomisation into an intervention group that received voice rehabilitation and a control group without rehabilitation. All patients underwent acoustic analysis, perceptual and subjective analysis of voice before the commencement of chemoradiotherapy and at 1, 3 and 6 months after chemoradiotherapy.

Results

In both groups, all parameters were significantly altered at one month follow-up except for fundamental frequency (females in control group and males in intervention group). In the intervention group, all parameters returned to pretreatment levels (no statistical differences) at 6 months. In the control group, all except for a few subjective parameters (grade, breathiness and asthenia) remained significantly altered at 6 months compared to the levels before radiotherapy.

Conclusions

In non-laryngeal head and neck malignancies, voice rehabilitation offered at 1 month after treatment ameliorates chemoradiation-induced dysphonia within 6 months.

Radiation-induced neuropathies in head and neck cancer: prevention and treatment modalities

Head and neck cancer (HNC) is the sixth most common human malignancy with a global incidence of 650,000 cases per year. Radiotherapy (RT) is commonly used as an effective therapy to treat tumours as a definitive or adjuvant treatment. Despite the substantial advances in RT contouring and dosage delivery, patients suffer from various radiation-induced complications, among which are toxicities to the nervous tissues in the head and neck area. Radiation-mediated neuropathies manifest as a result of increased oxidative stress-mediated apoptosis, neuroinflammation and altered cellular function in the nervous tissues. Eventually, molecular damage results in the formation of fibrotic tissues leading to susceptible loss of function of numerous neuronal substructures. Neuropathic sequelae following irradiation in the head and neck area include sensorineural hearing loss, alterations in taste and smell functions along with brachial plexopathy, and cranial nerves palsies. Numerous management options are available to relieve radiation-associated neurotoxicities notwithstanding treatment alternatives that remain restricted with limited benefits. In the scope of this review, we discuss the use of variable management and therapeutic modalities to palliate common radiation-induced neuropathies in head and neck cancers.

Induction of Fibrogenic Phenotype in Human Mesenchymal Stem Cells by Connective Tissue Growth Factor in a Hydrogel Model of Soft Connective Tissue

Scar formation is the typical endpoint of wound healing in adult mammalian tissues. An overactive or prolonged fibrogenic response following injury leads to excessive deposition of fibrotic proteins that promote tissue contraction and scar formation. Although well-defined in the dermal tissue, the progression of fibrosis is less explored in other connective tissues, such as the vocal fold. To establish a physiologically relevant 3D model of loose connective tissue fibrosis, we have developed a synthetic extracellular matrix using hyaluronic acid (HA) and peptidic building blocks carrying complementary functional groups. The resultant network was cell adhesive and protease degradable, exhibiting viscoelastic properties similar to the human vocal fold. Human mesenchymal stem cells (hMSCs) were encapsulated in the HA matrix as single cells or multicellular aggregates and cultured in pro-fibrotic media containing connective tissue growth factor (CTGF) for up to 21 days. hMSCs treated with CTGF-supplemented media exhibited an increased expression of fibrogenic markers and ECM proteins associated with scarring. Incorporation of α-smooth muscle actin into F-actin stress fibers was also observed. Furthermore, CTGF treatment increased the migratory capacity of hMSCs as compared to the CTGF-free control groups, indicative of the development of a myofibroblast phenotype. Addition of an inhibitor of the mitogen-activated protein kinase (MAPK) pathway attenuated cellular expression of fibrotic markers and related ECM proteins. Overall, this study demonstrates that CTGF promotes the development of a fibrogenic phenotype in hMSCs encapsulated within an HA matrix and that the MAPK pathway is a potential target for future therapeutic endeavors towards limiting scar formation in loose connective tissues.

Efficacy of Voice Therapy in Improving Vocal Function in Adults Irradiated for Laryngeal Cancers: A Pilot Study

BACKGROUND

Radiation therapy (XRT) for laryngeal cancers causes acute and chronic vocal dysfunction. Although these deleterious effects of XRT are well-established, there is a dearth of research with respect to effective voice rehabilitation following XRT for laryngeal cancers.

OBJECTIVE

To obtain preliminary data on the efficacy of voice rehabilitation, using vocal function exercises (VFEs) in improving vocal function in adults irradiated for laryngeal cancer. The comparison treatment group (VH) received vocal hygiene counseling.

STUDY DESIGN

Randomized clinical trial.

METHODS

Participants were randomized to the VFE + VH or VH group. Both interventions lasted 6 weeks. The primary outcome measure was improvement in VHI scores. Secondary outcome measures included auditory-perceptual assessments, acoustic and aerodynamic measures, and laryngeal imaging.

RESULTS

Ten participants were recruited for the study. The VFE + VH (n = 6) group demonstrated a statistically significant improvement in the primary outcome measure (P = 0.03), as well as select parameters of all secondary outcome measures. The VH (n = 4) group did not demonstrate a statistically significant improvement in primary or secondary outcome measures.

CONCLUSIONS

This study offers preliminary data for the utility of VFEs in the irradiated laryngeal cancer population. However, findings in the VFE + VH group lack generalizability, secondary to sample heterogeneity, and limited sample size.

Application of Manual Therapy for Dysphagia in Head and Neck Cancer Patients: A Preliminary National Survey of Treatment Trends and Adverse Events

BACKGROUND

Radiation-associated dysphagia is a common and debilitating consequence of treatment for head and neck cancer (HNC). Since commonly employed dysphagia therapy programs for HNC patients still lack authoritative efficacy, some speech-language pathologists (SLPs) have started employing manual therapy (MT) techniques in an attempt to prevent or rehabilitate dysphagia in this patient population. However, exceptionally little is known about the use of MT in this patient population.

OBJECTIVES

The purpose of this study was to describe practice patterns as well as the rate, type, and severity of adverse events associated with SLP provision of MT to HNC patients.

METHODS

An Internet-based questionnaire geared toward SLPs who practice MT was developed and sent to SLPs practicing in the United States, 3 times, through 3 national listservs (American Speech Language Hearing Association [ASHA] Special Interest Division 13, ASHA Special Interest Division 3, and University of Iowa Voiceserv), over the course of 4 weeks.

RESULTS

Of the 255 respondents, 116 (45.5%) performed MT on HNC patients. Of these 116 SLPs, 27.6% provided proactive MT during radiation, 62.1% provided 1 to 2 sessions per week, and 94.8% prescribed a MT home program. The rate, type, and severity of reported adverse events were similar between HNC and non-HNC patients.

CONCLUSION

This preliminary survey demonstrated that SLPs provide MT to HNC patients during and after cancer treatment, and that reported adverse events paralleled those experienced by noncancer patients. However, these results should be taken with caution, and a well-designed prospective study is needed to formally establish the safety and the preliminary efficacy of this novel clinical intervention.

Voice Outcomes After Radiation for Early-Stage Laryngeal Cancer

OBJECTIVES

Radiation treatment for laryngeal cancer has been shown to cause tissue changes to the vocal folds, which can result in degradation of voice. Our objective in this study was to investigate changes in perceptual, acoustic, and patient-reported outcomes over an extended period of follow-up after radiation.

DESIGN

Retrospective review.

METHODS

All patients treated with radiation for early-stage laryngeal carcinoma (in situ, T1, or T2) by a single surgeon from 2011-2018 were reviewed. Demographics and treatment information were recorded. Only patients with at least two dates of follow-up with acoustic data (cepstral spectral index of dysphonia [CSID]) and patient-reported surveys (voice handicap index-10 [VHI-10]) were included. Voice samples were rated by two senior speech-language pathologists on the grade, roughness, breathiness, asthenia, and strain scale.

RESULTS

Of 115 patients with early-stage laryngeal cancer, 31 patients met inclusion criteria. The average follow-up from time of treatment was 9.6 years (range 3.0-20.3 years), and the average time in between the first and last voice recordings was 2.6 years (range 0.3-5.5 years). The lesions represented were carcinoma in situ (n = 4), T1 (n = 22), and T2 (n = 5). The VHI-10 scores worsened slightly (mean increase +0.27, median +1) from first to last measurements as did the CSID score (median increase +7.0, median +7.4), though neither reached statistical significance when correlated with time since radiation (P = 0.269 and P = 0.0850). Perceptual analysis as rated by two speech-language pathologists raters showed excellent inter-rater reliability (Cronbach's alpha = 0.84), with no significant change over time (mean +0.39, median, with P = 0.347). Grade, roughness, breathiness, asthenia, and strain, VHI-10, and CSID were all correlated (all pairwise comparisons P < 0.001).

CONCLUSION

Perceptual, acoustic, and patient-reported outcomes years after radiation for early-stage laryngeal cancer do not show voice degradation over time in this preliminary analysis. Further research with a larger cohort may elucidate voice changes in this population.

Acute Nanoparticle Exposure to Vocal Folds: A Laboratory Study

OBJECTIVES

Airway exposure to nanoparticles is common in occupational settings. Inhaled nanoparticles have toxic effects on respiratory tissue. Vocal folds are also at direct risk from inhaled nanoparticles. This study investigated the effects of single-walled carbon nanotubes (SWCNT), a type of nanoparticle, on vocal fold epithelium and fibroblasts. These cell types were selected for study as the epithelium is the outer layer of the vocal folds and fibroblasts are the most common cell type in connective tissue underlying the epithelium.

METHODS

Native porcine vocal fold epithelium and cultured human vocal fold fibroblasts were exposed to SWCNTs (100 ng/mL) and control (no SWCNT) in vitro. Epithelial and fibroblast viability was measured using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Epithelial barrier integrity was assessed with transepithelial resistance and sodium fluorescein permeability. Epithelial tight junctional protein occludin expression was measured with Western blot. Gene expressions of the fibroblast-specific protein 1 (FSP-1), α-smooth muscle actin (α-SMA), and collagen III (Col-III) were assessed using quantitative polymerase chain reaction.

RESULTS

Transcriptional expression of genes encoding FSP-1 and Col-III was increased significantly following SWCNT exposure. There were no significant differences between control and SWCNT groups on any of the other measures.

CONCLUSIONS

SWCNT exposure induces vocal fold fibroblasts to a fibrotic phenotype. These data help us understand vocal fold defense mechanisms and lay the groundwork for studying the physiological effects of nanoparticle exposure in vivo.

Characteristics of speech production in patients with T1 glottic cancer who underwent laser cordectomy or radiotherapy

PURPOSE

Laser cordectomy (LC) or radiotherapy (RT) is often recommended in the early stage of laryngeal cancer. We conducted perceptual and acoustic analysis to compare sustained vowel and stop consonants since there is no article evaluating both the sustained vowel and stop consonants. Eventually, we might determine which management is superior in terms of speech production.

SUBJECTS AND METHODS

A total of 28 patients who underwent LC and RT for early T1 glottic cancer were selected. The sustained vowel /a/ and bilabial stop consonants were used to assess the perceptual scores. The fundamental frequency (F_o), jitter, shimmer and noise-to-harmonic ratio (NHR) levels for sustained vowels were evaluated. Voice onset time (VOT), vowel duration (VD) and closure duration of the bilabial plosives were analyzed. A receiver operating characteristic curve analysis was used to evaluate significant results statistically.

RESULTS

The GRBAS and discrimination scores were not significantly different between two groups. F_o and jitter were significantly higher in the LC than RT. The cut-off value was statistically higher in the LC group and statistically lower in the RT group. The VOT was significantly longer in the LC than RT. The cut-off value of the /pipida/ VOT was statistically longer in the LC group and statistically shorter in the RT group.

CONCLUSIONS

The differences may have been due to muscular fibrosis after RT. Movements of vocal cords with fibrosis were sluggish, when impulsion developed to pronounce the initial /p/ sound, so the VOT was shortened and the VD was longer after RT.

Comparative characteristics of laryngeal-resident mesenchymal stromal cell populations isolated from distinct sites in the rat larynx

BACKGROUND

Although tissue-resident mesenchymal stromal cells (MSCs) in the larynx have been described, their distinct characteristics and roles have not been thoroughly explored. Therefore, we investigated stem cell characteristics and regenerative potentials of single clonal populations isolated from rat epiglottic mucosa (EM), lamina propria (LP), and macula flava (MF) to determine whether they comprised laryngeal tissue-resident stem cells.

METHODS

Single clonal laryngeal cells were isolated following microdissection of the EM, LP, and MF from the rat larynx. Several clonal populations from the three laryngeal subsites were selected and expanded in vitro. We compared the stem cell characteristics of self-renewal and differentiation potential, as well as the cell surface phenotypes and gene expression profiles, of laryngeal MSC-like cells to that of bone marrow MSCs (BM-MSCs). We also investigated the regenerative potential of the laryngeal cells in a radiation-induced laryngeal injury animal model.

RESULTS

Self-renewing, clonal cell populations were obtained from rat EM, LP, and MF. EM-derived and LP-derived clonal cells had fibroblast-like features, while MF-resident clonal cells had stellate cell morphology and lipid droplets containing vitamin A. All laryngeal clonal cell populations had MSC-like cell surface marker expression (CD29, CD44, CD73, and CD90) and the potential to differentiate into bone and cartilage cell lineages; EM-derived and MF-derived cells, but not LP-derived cells, were also able to differentiate into adipocytes. Clonal cells isolated from the laryngeal subsites exhibited differential extracellular matrix-related gene expression. We found that the mesenchymal and stellate cell-related genes desmin and nestin were enriched in laryngeal MSC-like cells relative to BM-MSCs (P < 0.001). Growth differentiation factor 3 (GDF3) and glial fibrillary acidic protein (GFAP) transcript and protein levels were higher in MF-derived cells than in other laryngeal populations (P < 0.001). At 4 weeks after transplantation, laryngeal MF-derived and EM-derived cells contributed to laryngeal epithelial and/or glandular regeneration in response to radiation injury.

CONCLUSIONS

These results suggest that cell populations with MSC characteristics reside in the EM, LP, and MF of the larynx. Laryngeal MSC-like cells contribute to regeneration of the larynx following injury; further investigation is needed to clarify the differential roles of the populations in laryngeal tissue regeneration, as well as the clinical implications for the treatment of laryngeal disease.

Evaluating Post-Radiotherapy Laryngeal Function with Laryngeal Videostroboscopy in Early Stage Glottic Cancer

Objective

Dysphonia is common among patients with early stage glottic cancer. Laryngeal videostroboscopy (LVS) has not been routinely used to assess post-radiotherapy (RT) voice changes. We hypothesized that LVS would demonstrate improvement in laryngeal function after definitive RT for early-stage glottic cancer.

Study design

Blinded retrospective review of perceptual voice and stroboscopic parameters for patients with early glottic cancer and controls.

Setting

High-volume, single-institution academic medical center.

Subjects and methods

Fifteen patients underwent RT for Tis-T2N0M0 glottic cancer and were evaluated with serial LVS exams pre- and post-RT. Stroboscopic assessment included six parameters: vocal fold (VF) vibration, VF mobility, erythema/edema, supraglottic compression, glottic closure, and secretions. Grade, roughness, breathiness, asthenia, strain (GRBAS) voice perceptual scale was graded in tandem with LVS score. Assessments were grouped by time interval from RT: pre-RT, 0–4, 4–12, and >12 months post-RT.

Results

60 LVS exams and corresponding GRBAS assessments were reviewed. There were significant improvements in ipsilateral VF motion (P = 0.03) and vibration (P = 0.001) and significant worsening in contralateral VF motion (P < 0.001) and vibration (P = 0.008) at >12 months post-RT. Glottic closure significantly worsened, most prominent >12 months post-RT (P = 0.01). Composite GRBAS scores were significantly improved across all post-RT intervals.

Conclusion

LVS proved to be a robust tool for assessing pre- and post-RT laryngeal function. We observed post-RT improvement in ipsilateral VF function, a decline in contralateral VF function, and decreased glottic closure. These results demonstrate that LVS can detect meaningful changes in VF and glottic function and support its use for post-RT evaluation of glottic cancer patients.

Impact of Compliance on Dysphagia Rehabilitation in Head and Neck Cancer Patients: Results from a Multi-center Clinical Trial

A 5-year, 16-site, randomized controlled trial enrolled 170 HNC survivors into active (estim + swallow exercise) or control (sham estim + swallowing exercise) arms. Primary analyses showed that estim did not enhance swallowing exercises. This secondary analysis determined if/how patient compliance impacted outcomes. A home program, performed 2 times/day, 6 days/week, for 12 weeks included stretches and 60 swallows paired with real or sham estim. Regular clinic visits ensured proper exercise execution, and detailed therapy checklists tracked patient compliance which was defined by mean number of sessions performed per week (0-12 times) over the 12-week intervention period. "Compliant" was defined as performing 10-12 sessions/week. Outcomes were changes in PAS, HNCI, PSS, OPSE, and hyoid excursion. ANCOVA analyses determined if outcomes differed between real/sham and compliant/noncompliant groups after 12 weeks of therapy. Of the 170 patients enrolled, 153 patients had compliance data. The mean number of sessions performed was 8.57/week (median = 10.25). Fifty-four percent of patients (n = 83) were considered "compliant." After 12 weeks of therapy, compliant patients in the sham estim group realized significantly better PAS scores than compliant patients in the active estim group (p = 0.0074). When pooling all patients together, there were no significant differences in outcomes between compliant and non-compliant patients. The addition of estim to swallowing exercises resulted in worse swallowing outcomes than exercises alone, which was more pronounced in compliant patients. Since neither compliant nor non-compliant patients benefitted from swallowing exercises, the proper dose and/or efficacy of swallowing exercises must also be questioned in this patient population.

Cellular source and proinflammatory roles of high-mobility group box 1 in surgically injured rat vocal folds

Objectives/Hypothesis

High‐mobility group box 1 (HMGB1) is a chromatin‐binding protein located in the cell nucleus. Following injury, immunocompetent cells secrete HMGB1 to the extracellular milieu under the stimulation of proinflammatory cytokines. Extracellular HMGB1 acts a danger signal that instigates the innate immunity and tissue repair. We previously reported HMGB1 in the vocal fold extracellular compartment between day 3 and day 7 following surgical injury. In this study, we further investigated the cell source of HMGB1 and the relationship of proinflammatory cytokine expression and HMGB1 translocation in wounded vocal folds.

Study Design

Prospective animal study.

Methods

Bilateral vocal fold injury was performed on 122 Sprague‐Dawley rats. An additional 18 rats served as uninjured controls. Animals were sacrificed at multiple time points up to 4 weeks after surgery. Immunohistochemical costaining was performed to identify the cell source of HMGB1. Cell markers ED1, fibroblast‐specific protein 1 (FSP1), and alpha smooth muscle actin (α‐SMA) were used to identify macrophages, fibroblasts, and myofibroblasts, respectively. Enzyme‐linked immunosorbent assays were performed to measure cytokine levels of interleukin‐1beta (IL‐1β) and tumor necrosis factor‐alpha (TNF‐α) in vocal fold tissue.

Results

Costaining of HMGB1 was strong with ED1 and FSP1 but was minimal with α‐SMA in injured vocal folds. Compared to uninjured controls, IL‐1β and TNF‐α expression increased significantly the first 2 days after injury.

Conclusions

Macrophages and fibroblasts were a major cell source of vocal fold HMGB1. Translocation of HMGB1 may be an active response to the early accumulation of IL‐1β and TNF‐α in the wounded vocal folds.

Level of Evidence

NA Laryngoscope, 127:E193–E200, 2017

Mid-membranous Vocal Fold Webs: Case Series

INTRODUCTION

Laryngeal webs are a rare clinical entity, with those in the mid-membranous region occurring even less commonly. This is the first case series describing this condition.

CASE REPORT

We describe the clinical course of four patients with mid-glottic webs and propose the possible pathophysiology.

DISCUSSION

Trauma to the vocal folds followed by an inflammatory reaction is the likely event leading to the development of this lesion. Endoscopic division of this type of web has shown good postoperative voice outcomes without any recurrences.

CONCLUSION

The mid-glottic web is a rare clinical entity for which there is no defined etiology. It is likely that trauma results in an inflammatory reaction and, ultimately, web formation. Further studies are needed to identify risk factors for this condition.

Polarization response of second-harmonic images for different collagen spatial distributions

The response to polarization of second-harmonic generation (SHG) microscopy images of samples with different collagen distributions (quasialigned, partially organized, and nonorganized) has been analyzed. A linear decay relationship between the external arrangement and polarization sensitivity was found. SHG signal from nonorganized samples presented a large structural dispersion and a weak dependence with incident polarization. Polarization dependence is also associated with the internal organization of the collagen fibers, directly related to the ratio of hyperpolarizabilities ρ. This parameter can experimentally be computed from the modulation of the SHG signal. The results show that both external and internal collagen structures are closely related. This provides a tool to obtain information of internal properties from the polarimetric response of the external spatial distribution of collagen, which might be useful in clinical diagnosis of pathologies related to changes in collagen structure.

Low-level laser therapy/photobiomodulation in the management of side effects of chemoradiation therapy in head and neck cancer: part 2: proposed applications and treatment protocols

PURPOSE

There is a large body of evidence supporting the efficacy of low-level laser therapy (LLLT), more recently termed photobiomodulation (PBM) for the management of oral mucositis (OM) in patients undergoing radiotherapy for head and neck cancer (HNC). Recent advances in PBM technology, together with a better understanding of mechanisms involved and dosimetric parameters may lead to the management of a broader range of complications associated with HNC treatment. This could enhance patient adherence to cancer therapy, and improve quality of life and treatment outcomes. The mechanisms of action, dosimetric, and safety considerations for PBM have been reviewed in part 1. Part 2 discusses the head and neck treatment side effects for which PBM may prove to be effective. In addition, PBM parameters for each of these complications are suggested and future research directions are discussed.

METHODS

Narrative review and presentation of PBM parameters are based on current evidence and expert opinion.

RESULTS

PBM may have potential applications in the management of a broad range of side effects of (chemo)radiation therapy (CRT) in patients being treated for HNC. For OM management, optimal PBM parameters identified were as follows: wavelength, typically between 633 and 685 nm or 780-830 nm; energy density, laser or light-emitting diode (LED) output between 10 and 150 mW; dose, 2-3 J (J/cm(2)), and no more than 6 J/cm(2) on the tissue surface treated; treatment schedule, two to three times a week up to daily; emission type, pulsed (<100 Hz); and route of delivery, intraorally and/or transcutaneously. To facilitate further studies, we propose potentially effective PBM parameters for prophylactic and therapeutic use in supportive care for dermatitis, dysphagia, dry mouth, dysgeusia, trismus, necrosis, lymphedema, and voice/speech alterations.

CONCLUSION

PBM may have a role in supportive care for a broad range of complications associated with the treatment of HNC with CRT. The suggested PBM irradiation and dosimetric parameters, which are potentially effective for these complications, are intended to provide guidance for well-designed future studies. It is imperative that such studies include elucidating the effects of PBM on oncology treatment outcomes.

Analysis and quantification of collagen organization with the structure tensor in second harmonic microscopy images of ocular tissues

The important biological role of collagen-based tissues and the changes produced in the fiber distribution under particular situations (surgery, pathology, external damage, etc.) require tools for the analysis of the collagen organization that might potentially help in early diagnoses. Since collagen structures provide efficient second harmonic generation (SHG) signals, SHG microscopy has emerged as a powerful technique to visualize collagen fibers and qualitatively discriminate normal from abnormal tissues. Here we propose a quantitative method based on the structure tensor to quantify the different organization of collagen patterns in SHG images of ocular tissues. Results show that well-organized collagen distributions present a high degree of isotropy (DoI), a dominant orientation (PO), and a low structural dispersion (SD). On the other hand, the PO vanishes when the collagen tissue is not organized as a consequence of an increase in the SD and a decrease in the DoI. The proposed method is also able to discriminate partially organized samples. The combination of SHG microscopy and the structure tensor is a useful method to objectively classify collagen distributions. Clinical applications of this technique could help in the diagnosis and tracking of pathologies related to collagen disorders in connective tissue.

Early Cellular Response to Radiation in Human Vocal Fold Fibroblasts

OBJECTIVES

Radiation therapy is a common treatment strategy for laryngeal carcinoma. However, radiation is not without adverse side effects, especially toward healthy vocal fold tissue, which can lead to long-term impairments in vocal function. The objective of this preliminary study was to investigate early responses of healthy human vocal fold fibroblasts (VFF) to radiation.

METHODS

VFF were exposed to a single or fractionated dose radiation scheme. Nonradiated VFF served as controls. Morphology of radiated and control VFF was subjectively examined. Quantitative polymerase chain reaction was used to evaluate the effect of radiation on extracellular matrix and inflammatory-related genes. VFF viability was investigated using a LIVE/DEAD and clonogenic assay.

RESULTS

Single or fractioned dose radiated VFF were morphologically indistinguishable from control VFF. No significant differences in gene expression were observed following either radiation scheme and as compared to controls. Clonogenic assay revealed reduced VFF viability following the fractionated but not single dose scheme. No changes in viability were detected using the LIVE/DEAD assay.

CONCLUSIONS

We present one of the first investigations to evaluate early responses of healthy VFF to radiation. Findings will contribute to a growing body of literature seeking to elucidate the biological mechanisms underlying voice changes following radiation therapy for laryngeal carcinoma.

RETRACTED: Laryngeal Function After Radiation Therapy

Laryngeal function after oncologic treatment is a key aspect and focus of interest in the contemporary management of head and neck cancers. Although historically the treatment of most locally advanced laryngeal cancers has been total laryngectomy, recent innovations in radiation therapy and combined chemotherapy and radiation therapy have shown that organ and function preservation can be achieved with good oncologic outcomes. Technical improvements, along with better understanding of tumor biology and dose tolerance of critical organs involved in speech and swallowing function, have paved the way for better outcomes. This article reviews in comprehensive detail the recent data of laryngeal function after radiotherapy.

microRNA alterations driving acute and late stages of radiation-induced fibrosis in a murine skin model

PURPOSE

Although ionizing radiation is critical in treating cancer, radiation-induced fibrosis (RIF) can have a devastating impact on patients' quality of life. The molecular changes leading to radiation-induced fibrosis must be elucidated so that novel treatments can be designed.

METHODS AND MATERIALS

To determine whether microRNAs (miRs) could be responsible for RIF, the fibrotic process was induced in the right hind legs of 9-week old CH3 mice by a single-fraction dose of irradiation to 35 Gy, and the left leg served as an unirradiated control. Fibrosis was quantified by measurements of leg length compared with control leg length. By 120 days after irradiation, the irradiated legs were 20% (P=.013) shorter on average than were the control legs.

RESULTS

Tissue analysis was done on muscle, skin, and subcutaneous tissue from irradiated and control legs. Fibrosis was noted on both gross and histologic examination by use of a pentachrome stain. Microarrays were performed at various times after irradiation, including 7 days, 14 days, 50 days, 90 days, and 120 days after irradiation. miR-15a, miR-21, miR-30a, and miR-34a were the miRs with the most significant alteration by array with miR-34a, proving most significant on confirmation by reverse transcriptase polymerase chain reaction, c-Met, a known effector of fibrosis and downstream molecule of miR-34a, was evaluated by use of 2 cell lines: HCT116 and 1522. The cell lines were exposed to various stressors to induce miR changes, specifically ionizing radiation. Additionally, in vitro transfections with pre-miRs and anti-miRs confirmed the relationship of miR-34a and c-Met.

CONCLUSIONS

Our data demonstrate an inverse relationship with miR-34a and c-Met; the upregulation of miR-34a in RIF causes inhibition of c-Met production. miRs may play a role in RIF; in particular, miR-34a should be investigated as a potential target to prevent or treat this devastating side effect of irradiation.