Dosimetric and radiobiological comparison of helical tomotherapy, forward-planned intensity-modulated radiotherapy and two-phase conformal plans for radical radiotherapy treatment of head and neck squamous cell carcinomas

Cell cycle associated miRNAs as target and therapeutics in lung cancer treatment

Lung cancer is the primary cause of cancer related deaths worldwide. Limited therapeutic options and resistance to existing drugs are the major hindrances to the clinical success of this cancer. In the past decade, several studies showed the role of microRNA (miRNA) driven cell cycle regulation in lung cancer progression. Therefore, these small nucleotide molecules could be utilized as promising tools in lung cancer therapy. In this review, we highlighted the recent advancements in lung cancer therapy using cell cycle linked miRNAs. By highlighting the roles of the specific cell cycle core regulators affiliated miRNAs in lung cancer, we further outlined how these miRNAs can be explored in early diagnosis and treatment strategies to prevent lung cancer. With the provided information from our review, more medical efforts can ensure a potential breakthrough in miRNA-based lung cancer therapy.

Pediatric Craniospinal Irradiation - The implementation and Use of Normal Tissue Complication Probability in Comparing Photon versus Proton Planning

Purpose:

The preferred radiotherapy treatment for medulloblastoma is craniospinal irradiation (CSI). With the aim of developing the potential to reduce normal tissue dose and associated post-treatment complications with photon and proton radiotherapy techniques for CSI. This report aims to carefully compare and rank treatment planning and dosimetric outcomes for pediatric medulloblastoma patients using normal tissue complication probability (NTCP) formalism between photon (three-dimensional conformal radiotherapy, intensity-modulated radiotherapy [IMRT], volumetric-modulated arc therapy [VMAT], and HT) and proton CSI.

Methods and Materials:

The treatment data of eight pediatric patients who typically received CSI treatment were used in this study. The patients were 7 years of age on average, with ages ranging from 3 to 11 years. A prescription dose of 3600 cGy was delivered in 20 fractions by the established planning methods. The Niemierko's and Lyman–Kutcher–Burman models were followed to carefully estimate NTCP and compare different treatment plans.

Results:

The NTCP of VMAT plans in upper and middle thoracic volumes was relatively high compared to helical tomotherapy (HT) and pencil beam scanning (PBS) (all P < 0.05). PBS rather than IMRT and VMAT in the middle thoracic region (P < 0.06) could significantly reduce the NTCP of the heart. PBS significantly reduced NTCP of the lungs and liver (all P < 0.05).

Conclusion:

The NTCP and tumor control probability (TCP) model-based plan ranking along with dosimetric indices will help the clinical practitioner or medical physicists to choose the best treatment plan for each patient based on their anatomical or clinical challenges.

Extreme long-term voice outcomes after concurrent chemoradiotherapy for advanced non-laryngeal head and neck cancer: Eight-year post-treatment analysis

BACKGROUND

The long-term effect of concurrent chemoradiation on voice outcomes in the context of non-laryngeal head and neck cancer is not established.

METHODS

A prospective, observational study to evaluate the voice quality in disease-free patients receiving concurrent chemoradiation for advanced non-laryngeal squamous cell carcinoma of the upper aerodigestive tract. Voice assessment occurred at four distinct time-points: pretreatment, 3, 12 and 92.6 months (mean) post-treatment in 34, 21 and nine patients, respectively. The authors used a combination of subjective (VoiSS questionnaire), expert rater-assessed (GRBAS scale) and acoustic analysis of the fundamental frequency to assess voice outcomes. Ethical approval was obtained from the United Kingdom National Research Ethics Service.

RESULTS

Both the VoiSS impairment and GRBAS domains continued to deteriorate over time from pre-treatment to 92.6 months post-treatment (P = 0.03). There was a strong correlation between increase in total VoiSS and GRBAS scores (r = 0.93). Acoustic analysis demonstrated no statistically significant variation in fundamental frequency.

CONCLUSION

Radiation therapy for advanced non-laryngeal head and neck has a significant, deleterious effect on voice, which is apparent up to eight years post-treatment.

Comparison of dose distribution for head and neck cancer patients with and without dose painting escalation during radiotherapy realized with tomotherapy unit

OBJECTIVE

To determine and quantify the percentage dose increase to organs at risk (OARs) with multiple-level dose painting (DP) for patients with head and neck cancer in comparison with standard regimen.

METHODS

12 patients who had undergone fluorine-18 fludeoxyglucose (¹⁸F-FDG) positron emission tomography (PET)/CT scan were retrospectively enrolled. Two treatment plans-one using DP escalation and one without-were optimized for each patient base on PET/CT data. The following variables were assessed: dose to OARs and target volumes; execution time; equivalent uniform dose; and normal tissue complication probability.

RESULTS

No statistically significant differences in beam-on time were observed between plans with and without DP. However, significantly higher doses were observed for all DP-escalated plans in the OARs, with only two exceptions: the brain stem and V_60Gy for the mandible. Multiple-level DP resulted in dose increases ranging from 3.0% to 12.9%, depending on the OAR. The largest increase was seen for the parotid glands and the smallest for the mandible. Significant differences in the equivalent uniform dose were observed only for the parotid glands and spinal column, where the dose without DP was lower. The normal tissue complication probability for most OARs was very small.

CONCLUSION

Importantly, even though DP escalation resulted in higher doses to OARs vs conventional treatment planning, these usually did not exceed the dose tolerance levels. However, clinical trials are necessary to confirm the benefits of DP and to guarantee no additional toxicity. Advances in knowledge: Multiple-level DP by numbers resulted in 3.0-12.9% dose increase, depending on the OAR. Our findings may suggest that DP escalation to very high doses is feasible for about 83% of patients without higher toxicity; however, it still should be confirmed on a larger group of patients.

Endoplasmic reticulum stress-mediated pathways to both apoptosis and autophagy: Significance for melanoma treatment

Melanoma is the most aggressive form of skin cancer. Disrupted intracellular signaling pathways are responsible for melanoma's extraordinary resistance to current chemotherapeutic modalities. The pathophysiologic basis for resistance to both chemo- and radiation therapy is rooted in altered genetic and epigenetic mechanisms that, in turn, result in the impairing of cell death machinery and/or excessive activation of cell growth and survival-dependent pathways. Although most current melanoma therapies target mitochondrial dysregulation, there is increasing evidence that endoplasmic reticulum (ER) stress-associated pathways play a role in the potentiation, initiation and maintenance of cell death machinery and autophagy. This review focuses on the reliability of ER-associated pathways as therapeutic targets for melanoma treatment.

MicroRNA-216a enhances the radiosensitivity of pancreatic cancer cells by inhibiting beclin-1-mediated autophagy

Radioresistance has become a challenge in the treatment of pancreatic cancer, which limits the efficacy and outcomes of radiotherapy in clinical treatment. Autophagy, recognized as an adaptive response to cell stress, has recently been involved in the radioresistance of cancer cells. MicroRNAs (miRNAs) are also involved in the radioresistance of pancreatic cancer cells. In the present study, we established a radioresistant pancreatic cancer cell line and found that miRNA-216a was significantly downregulated whereas the autophagy activity was increased as compared with the control. Forced expression of miR-216a was found to inhibit the expression of beclin-1, a critical autophagic gene, as well as autophagy. Using bioinformatics analysis and the dual-luciferase reporter gene assay, we found that miR-216a directly interacted with 3'-untranslated region (UTR) of beclin-1. Furthermore, the forced expression of miR‑216a inhibited cell growth and colony formation ability and promoted the cell apoptosis of radioresistant pancreatic cancer cells in response to irradiation. By contrast, overexpression of beclin-1 abrogated the effects of miR-216a. Furthermore, miR-216a sensitized xenograft tumor to irradiation treatment and inhibited irradiation-induced autophagy by regulating beclin-1. Collectively, the results demonstrated that miR‑216a enhanced the radiosensitivity of pancreatic cancer cells by inhibiting beclin-1-mediated autophagy, suggesting a promising molecular target for improving the radiotherapy of pancreatic cancer.

Dose-response effect of human equivalent radiation in the mandible

BACKGROUND

Despite widespread use of adjuvant irradiation for head and neck cancer, the extent of damage to the underlying bone is not fully understood but is associated with pathologic fractures, nonunion, and osteoradionecrosis. The authors' laboratory previously demonstrated that radiation significantly impedes new bone formation in the murine mandible. We hypothesize that the detrimental effects of human equivalent radiation on the murine mandible results in a dose-dependent degradation in traditional micro-computed tomography (micro-CT) metrics.

METHODS

Fifteen male Sprague-Dawley rats were randomized into 3 radiation dosage groups: low (5.91 Gy), middle (7 Gy), and high (8.89 Gy), delivered in 5 daily fractions. These dosages approximated 75%, 100%, and 150%, respectively, of the biologically equivalent dose that the human mandible receives during radiation treatment. Hemimandibles were harvested 56 days after radiation and scanned using micro-CT. Bone mineral density, tissue mineral density, and bone volume fraction were measured along with microdensitometry measurements.

RESULTS

Animals demonstrated dose-dependent adverse effects of mucositis, alopecia, weight loss, and mandibular atrophy with increasing radiation. Traditional micro-CT parameters were not sensitive enough to demonstrate statistically significant differences between the radiated groups; however, microdensitometry analysis showed clear differences between radiated groups and statistically significant changes between radiated and nonradiated groups.

CONCLUSIONS

The authors report dose-dependent and clinically significant adverse effects of fractionated human equivalent radiation to the murine mandible. The authors further report the limited capacity of traditional micro-CT metrics to adequately capture key changes in bone composition and present microdensitometric histogram analysis to demonstrate significant radiation-induced changes in mineralization patterns.

Effect of miR-18a overexpression on the radiosensitivity of non-small cell lung cancer

The aim of the present study is to investigate whether there is a relationship between miR-18a expression and radiosensitization of non-small-cell lung caner (NSCLC). The relationship between miR-18a expression and clinicopathological characteristics was investigated. To determine whether the miR-18a expression levels were associated with radiotherapeutic efficacy, therapeutic response was evaluated by radiologic Response Evaluation Criteria in Solid Tumors (RECIST). To determine whether miR-18a was required for lung cancer cell radioresistance, A549 cells were treated with different doses of ionizing radiation, following transfection with inhibitor miR-18a or inhibitor NC. We found that the level of miR-18a in NSCLC was strongly correlated with tumor differentiation (P = 0.026), regional lymph node metastasis (P = 0.013) and clinical TNM stage (P = 0.005). According to RECIST, miR-18a expression level was significantly associated with therapeutic response, exhibiting higher expression level in non-responsive patients. Furthermore, the depletion of miR-18a increased A549 cell radiosensitivity. In conclusion, we provide the evidence that down-regulation of miR-18a sensitizes NSCLC to radiation treatment, and it may help to develop a new approach to sensitizing radioresistant lung cancer cells by targeting miR-18a.

MicroRNA-21 is a novel promising target in cancer radiation therapy

MicroRNAs (miRNAs) represent an important nonprotein part of the human genome in tumor biology. Among the several types of miRNAs, microRNA-21 (miR-21) is dysregulated in several types of cancer and plays a key role in carcinogenesis, recurrence, and metastasis. Thus, it can be a potential target for cancer therapy including radiation therapy. In this review, we focus on miR-21, which has been identified in human cancer tissues, to suggest reasonable strategies for future research. miR-21 may have an influence on cell cycle, DNA damage repair, apoptosis, autophagy, and hypoxia of cancer during irradiation. We review the use of miR-21 in cancer radiation therapy and describe the known functions and possible underlying molecular mechanisms of miR-21 in radiosensitivity and radioresistance. Furthermore, the current and potential future applications of miR-21 in cancer radiation therapy are also discussed.

Predictors of weight loss during conformal radiotherapy for head and neck cancers - how important are planning target volumes?

AIMS

Nutritional compromise is common during high dose radiotherapy (RT) or chemoradiotherapy (CRT) for head and neck cancers. We aimed to identify the factors that determine nutritional outcome for head and neck cancer patients during radiotherapy.

METHODS

Data from 103 patients with head and neck cancer treated with highly conformal radiotherapy to doses of 60 Gy or more in 30-33 fractions in the adjuvant or definitive setting was analyzed. All patients received complex 3D conformal radiotherapy (3DCRT) or intensity modulated radiotherapy (IMRT). Patients received regular nutritional counseling and need-based interventions. Their weight was recorded at the beginning and end of radiotherapy. Using univariate and multivariate models we tested possible predictors of weight loss of >5% and NG tube requirement.

RESULTS

The mean weight loss was 3.8%. The incidence of weight loss >5% was 37.9% and NG tube placement was 24.3%. The factors significantly associated with >5% weight loss in the univariate analysis were tumor site (oro-hypopharyngeal vs. others), definitive vs. adjuvant RT; prescription dose of >60 Gy vs. 60 Gy; CRT vs. RT alone; prescription dose planning target volume (PTV) volume >235 cc and total PTV volume >615 cc. Age, sex, T stage, N stage and modality (3DCRT/IMRT) were not significant. In multivariate analysis, the total PTV volume, prescription dose PTV volume and use of chemotherapy were significant after controlling for other factors. Patients could be risk stratified based on the use of CRT and large PTV volumes. Patients with none, one or both factors had a likelihood of >5% weight loss of 0%, 30.3%, and 56.9% (p < 0.001) and likelihood of NG tube placement of 5.3%, 15.2% and 37.3% (p = 0.007).

CONCLUSIONS

It is possible to predict weight loss and NG tube requirements from disease and treatment related factors. PTV volumes are important predictors of nutritional compromise. Risk stratification may enable more focused counseling and identification of patients who require preventive interventions.

Regulatory mechanisms and clinical perspectives of miRNA in tumor radiosensitivity

MicroRNA (miRNA) influences carcinogenesis at multiple stages and it can effectively control tumor radiosensitivity by affecting DNA damage repair, cell cycle checkpoint, apoptosis, radio-related signal transduction pathways and tumor microenvironment. MiRNA also efficiently modulates tumor radiosensitivity at multiple levels by blocking the two essential non-homologous end-joining repair and homologous recombination repair pathways in the DNA damage response. It interferes with four radio-related pathways in ionizing radiation, including the PI3-K/Akt, NF-κB, MAPK and TGFβ signaling pathways. Moreover, the regulatory effect of miRNA in radiosensitivity can be enhanced when interacting with various key molecules, including H2AX, BRCA1, ATM, DNA-PK, RAD51, Chk1, Cdc25A, p53, PLK1, HIF-1 and VEGF, which are involved in these processes. Therefore, thoroughly understanding the mechanism of miRNA in tumor radiosensitivity could assist in finding novel targets to improve the radiotherapeutic effects and provide new clinical perspectives and insights for developing effective cancer treatments.