Hypothyroidism following Radiotherapy for Head and Neck Cancer: A Systematic Review of the Literature and Opportunities to Improve the Therapeutic Ratio

(1) Background: Radiotherapy (RT) is a central component for the treatment of many head and neck cancers. In this systematic review of the literature, we aimed to characterize and quantify the published evidence on RT-related hypothyroidism, including estimated incidence, clinical risk factors, and dosimetric parameters that may be used to guide clinical decision making. Furthermore, we aimed to identify potential areas of improvement in the prevention and clinical management of RT-induced hypothyroidism, including the role of modern advanced therapeutic techniques. (2) Methods: We conducted a systemic review of the literature in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines. PubMed and Google Scholar were searched to identify original research articles describing the incidence, mechanism, dosimetry, treatment, or prevention of radiation-related hypothyroidism for adults receiving RT for the treatment of head and neck cancers. The snowball method was used to identify additional articles. For identified articles, we tabulated several datapoints, including publication date, patient sample size, estimated hypothyroidism incidence, cancer site/type, follow-up period, radiation modality and technique, use of multimodality therapy, method of thyroid function evaluation, and proposed dosimetric predictors of hypothyroidism. (3) Results: One hundred and eleven articles met inclusion criteria, reflecting a range of head and neck cancer subtypes. There was a large variation in the estimated incidence of RT-related hypothyroidism, with a median estimate of 36% (range 3% to 79%). Reported incidence increased in later publication dates, which was likely related to improved screening and longer follow up. There were a wide variety of predictive metrics used to identify patients at high risk of hypothyroidism, the most common of which were volumetric and mean dosimetrics related to the thyroid gland (Vxx%, Dmean). More recently, there has been increasing evidence to suggest that the thyroid gland volume itself and the volume of the thyroid gland spared from high-dose radiation (VSxx) may better predict thyroid function after RT. There were no identified studies investigating the role of advanced radiotherapeutic techniques such as MRI-guided RT or particle therapy to decrease RT-related hypothyroidism. Conclusions: Hypothyroidism is a common toxicity resulting from therapeutic radiation for head and neck cancer with recent estimates suggesting 40-50% of patients may experience hypothyroidism after treatment. Dosimetric predictive models are increasingly able to accurately identify patients at risk of hypothyroidism, especially those utilizing thyroid VS metrics. Further investigation regarding the potential for advanced radiotherapeutic therapies to decrease RT-induced thyroid dysfunction is needed.

Radiation for hematologic malignancies: from cell killing to immune cell priming

Over the past half-century, the role of radiotherapy has been revolutionized, in part, by a shift from intent to directly kill cancer cells to the goal of priming anti-tumor immune responses that attack both irradiated and non-irradiated tumors. Stimulation of anti-tumor immunity depends on the interplay between radiation, the tumor microenvironment, and the host immune system, which is a burgeoning concept in cancer immunology. While the interplay of radiotherapy and the immune system has been primarily studied in solid tumors, we are beginning to understand this interplay in hematological malignancies. The intent of this review is to lead readers through some of the important recent advances in immunotherapy and adoptive cell therapy, highlighting the best available evidence in support of incorporating radiation therapy and immunotherapy into the treatment of hematological malignancies. Evidence is presented regarding how radiation therapy 'converses' with the immune system to stimulate and enhance anti-tumor immune responses. This pro-immunogenic role of radiotherapy can be combined with monoclonal antibodies, cytokines and/or other immunostimulatory agents to enhance the regression of hematological malignancies. Furthermore, we will discuss how radiotherapy facilitates the effectiveness of cellular immunotherapies by acting as a "bridge" that facilitated CAR T cell engraftment and activity. These initial studies suggest radiotherapy may help catalyze a shift from using chemotherapy-intensive treatment to treatment that is "chemo-free" by combining with immunotherapy to target both the radiated and non-irradiated disease sites. This "journey" has opened the door for novel uses of radiotherapy in hematological malignancies due to its ability to prime anti-tumor immune responses which can augment immunotherapy and adoptive cell-based therapy.

Increased Disparities in Patients Diagnosed with Metastatic Lung Cancer Following Lung CT Screening in the United States

OBJECTIVES

We sought to determine if implementation of low dose computed tomography (LDCT) screening for lung cancer in the United States had led to changes in patients being diagnosed with metastatic lung cancer over time.

MATERIALS AND METHODS

The Surveillance, Epidemiology, and End Result (SEER) database was utilized to determine the proportion of lung cancers diagnosed as stage I to III and stage IV from 2009-2018. Changes in lung cancer stage distribution were compared in the overall population and by race.

RESULTS

From 2009 to 2018, the proportion of stage I to III lung cancers increased from 52% (51.3%-53.2%) in 2009 to 56% (54.0%-55.8%) in 2018 (P < .001). Correspondingly, the proportion of lung cancers diagnosed in stage IV decreased from 48% (46.8%-48.7%) in 2009 to 45% (44.2%-46.0%) (P < .001) in 2018. For white patients, the proportion increased from 53% (51.6%-53.7%) to 56% (55.1%-57.1%) (P < .001). However, for black patients, no trend was present, with the proportion being 51% (47.9%-53.4%) in 2009 and 52% (49.0%-54.2%) in 2018 (P = .303).

CONCLUSION

Since the implementation of LDCT screening, the proportion of early-stage lung cancers increased in the general population. These changes in stage distribution were not present in black patients.

Reprogramming of Neutrophils as Non-canonical Antigen Presenting Cells by Radiotherapy-Radiodynamic Therapy to Facilitate Immune-Mediated Tumor Regression

Ineffective antigen cross-presentation in the tumor microenvironment compromises the generation of antitumor immune responses. Radiotherapy-radiodynamic therapy (RT-RDT) with nanoscale metal-organic frameworks (nMOFs) induces robust adaptive immune responses despite modest activation of canonical antigen presenting dendritic cells. Here, using transplantable and autochthonous murine tumor models, we demonstrate that RT-RDT induces antitumor immune responses via early neutrophil infiltration and reprogramming. Intravenous or intratumoral injection of nMOFs recruited peripheral CD11b⁺Ly6G⁺CD11c^- neutrophils into tumors. The activation of nMOFs by low-dose X-rays significantly increased the population of CD11b⁺Ly6G⁺CD11c⁺ hybrid neutrophils with upregulated expression of the co-stimulatory molecules CD80 and CD86 as well as major histocompatibility complex class II molecules. Thus, nMOF-enabled RT-RDT reshapes a favorable tumor microenvironment for antitumor immune responses by reprogramming tumor-infiltrating neutrophils to function as non-canonical antigen presenting cells for effective cross-presentation of tumor antigens.

Machine Learning-Guided Adjuvant Treatment of Head and Neck Cancer

Importance

Postoperative chemoradiation is the standard of care for cancers with positive margins or extracapsular extension, but the benefit of chemotherapy is unclear for patients with other intermediate risk features.

Objective

To evaluate whether machine learning models could identify patients with intermediate-risk head and neck squamous cell carcinoma who would benefit from chemoradiation.

Design, Setting, and Participants

This cohort study included patients diagnosed with squamous cell carcinoma of the oral cavity, oropharynx, hypopharynx, or larynx from January 1, 2004, through December 31, 2016. Patients had resected disease and underwent adjuvant radiotherapy. Analysis was performed from October 1, 2019, through September 1, 2020. Patients were selected from the National Cancer Database, a hospital-based registry that captures data from more than 70% of newly diagnosed cancers in the United States. Three machine learning survival models were trained using 80% of the cohort, with the remaining 20% used to assess model performance.

Exposures

Receipt of adjuvant chemoradiation or radiation alone.

Main Outcomes and Measures

Patients who received treatment recommended by machine learning models were compared with those who did not. Overall survival for treatment according to model recommendations was the primary outcome. Secondary outcomes included frequency of recommendation for chemotherapy and chemotherapy benefit in patients recommended for chemoradiation vs radiation alone.

Results

A total of 33 527 patients (24 189 [72%] men; 28 036 [84%] aged ≤70 years) met the inclusion criteria. Median follow-up in the validation data set was 43.2 (interquartile range, 19.8-65.5) months. DeepSurv, neural multitask logistic regression, and survival forest models recommended chemoradiation for 17 589 (52%), 15 917 (47%), and 14 912 patients (44%), respectively. Treatment according to model recommendations was associated with a survival benefit, with a hazard ratio of 0.79 (95% CI, 0.72-0.85; P < .001) for DeepSurv, 0.83 (95% CI, 0.77-0.90; P < .001) for neural multitask logistic regression, and 0.90 (95% CI, 0.83-0.98; P = .01) for random survival forest models. No survival benefit for chemotherapy was seen for patients recommended to receive radiotherapy alone.

Conclusions and Relevance

These findings suggest that machine learning models may identify patients with intermediate risk who could benefit from chemoradiation. These models predicted that approximately half of such patients have no added benefit from chemotherapy.

A Phase 1 Trial Assessing the Safety and Tolerability of a Therapeutic DNA Vaccination Against HPV16 and HPV18 E6/E7 Oncogenes After Chemoradiation for Cervical Cancer

PURPOSE

This study assessed the safety and tolerability of therapeutic immunization against the human papillomavirus (HPV) viral oncoproteins E6 and E7 in patients with cervical cancer after chemoradiation.

METHODS AND MATERIALS

MEDI0457 (INO-3112) is a DNA-based vaccine targeting E6 and E7 of HPV-16/18 that is coinjected with an IL-12 plasmid followed by electroporation with the CELLECTRA 5P device. At 2 to 4 weeks after chemoradiation, patients with newly diagnosed stage IB1-IVA (cohort 1) or persistent/recurrent (cohort 2) cervical cancers were treated with 4 immunizations of MEDI0457 every 4 weeks. The primary endpoints were incidence of adverse events and injection site reactions. Immune responses against HPV antigens were measured by ELISpot for interferon-γ (IFNγ), enzyme-linked immunosorbent assay for antibody responses and multiplexed immunofluorescence for immune cells in cervical biopsy specimens.

RESULTS

Ten patients (cohort 1, n = 7; cohort 2, n = 3) with HPV16 (n = 7) or HPV18 (n = 3) cervical cancers received MEDI0457 after chemoradiation. Treatment-related adverse events were all grade 1, primarily related to the injection site. Eight of 10 patients had detectable cellular or humoral immune responses against HPV antigens after chemoradiation and vaccination: 6 of 10 patients generated anti-HPV antibody responses and 6 of 10 patients generated IFNγ-producing T cell responses. At the completion of chemoradiation and vaccination, cervical biopsy specimens had detectable CD8⁺ T cells and decreased PD-1⁺CD8⁺, PD-L1⁺CD8⁺, and PD-L1⁺CD68⁺ subpopulations. All patients cleared detectable HPV DNA in cervical biopsies by completion of chemoradiation and vaccination.

CONCLUSIONS

Adjuvant MEDI0457 is safe and well tolerated after chemoradiation for locally advanced or recurrent cervical cancers, supporting further investigation into combining tumor-specific vaccines with radiation therapy.

Association between intensity modulated radiotherapy and survival in patients with stage III non-small cell lung cancer treated with chemoradiotherapy

PURPOSE

To determine the effect of radiotherapy (RT) technique on treatment compliance and overall survival (OS) in patients with stage III non-small lung cancer (NSCLC) treated with definitive chemoradiotherapy (CRT).

METHODS AND MATERIALS

This study included patients with stage III NSCLC in the National Cancer Database treated between 2003 and 2011 with definitive CRT to 60-63 Gray (Gy). Radiation treatment interruption (RTI) was defined as a break of ≥4 days. Treatment technique was dichotomized as intensity modulated (IMRT) or non-IMRT techniques.

RESULTS

Out of the cohort of 7492, 35% had a RTI and 10% received IMRT. With a median follow-up of surviving patients of 32 months, the median survival for those with non-IMRT vs. IMRT was 18.2 months vs. 20 months (p<0.0001). Median survival for those with and without an RTI≥4 days was 16.1 months vs. 19.8 months (p<0.0001). Use of IMRT predicted for a decreased likelihood of RTI (odds ratio, 0.84, p=0.04). On multivariable analysis for OS, IMRT had a HR of 0.89 (95% CI: 0.80-0.98, p=0.01) and RTI had a HR of 1.2 (95% confidence interval (CI): 1.14-1.27, p=0.001).

CONCLUSIONS

IMRT was associated with small but significant survival advantage for patients with stage III NSCLC treated with CRT. A RTI led to inferior survival, and both IMRT and RTI were independently associated with OS. Additional research should investigate whether improved tolerability, reduced normal tissue exposure, or superior coverage drives the association between IMRT and improved survival.

The intersection of radiotherapy and immunotherapy: mechanisms and clinical implications

By inducing DNA damage, radiotherapy both reduces tumor burden and enhances anti-tumor immunity. Here, we will review the mechanisms by which radiation induces anti-tumor immune responses that can be augmented using immunotherapies to facilitate tumor regression. Radiotherapy increases inflammation in tumors by activating the NF-κB and the Type I interferon response pathways to induce expression of pro-inflammatory cytokines. This inflammation coupled with antigen release from irradiated cells facilitates dendritic cell maturation and cross-presentation of tumor antigens to prime tumor-specific T cell responses. Radiation also sensitizes tumors to these T cell responses by enhancing T cell infiltration into tumors and the recognition of both malignant cancer cells and non-malignant stroma that present cognate antigen. Yet, these anti-tumor immune responses may be blunted by several mechanisms including regulatory T cells and checkpoint molecules that promote T cell tolerance and exhaustion. Consequently, the combination of immunotherapy using vaccines and/or checkpoint inhibitors with radiation is demonstrating early clinical potential. Overall, this review will provide a global view for how radiation and the immune system converge to target cancers and the early attempts to exploit this synergy in clinical practice.

The effect of radiotherapy dose on survival in stage III non-small-cell lung cancer patients undergoing definitive chemoradiotherapy

BACKGROUND

In this study, we examined trends in the radiotherapy dose prescribed and the effect of dose escalation on survival in patients with stage III lung cancer.

MATERIALS AND METHODS

Radiation dose prescription patterns were analyzed for 38,848 patients in the National Cancer Database with clinical stage III disease who underwent concurrent chemoradiation between 2004 and 2011 to a dose between 57 and 80 Gy. Survival information was available for patients diagnosed from 2004 to 2006 (n = 12,024). Overall survival (OS) was estimated using Kaplan-Meier methods. Cox proportional hazard regression was used to estimate hazard ratios (HRs).

RESULTS

The percentage of patients treated to ≥ 64 Gy increased from 50% in 2004 to 62% in 2011 (P < .001). The 5-year OS was 12% for patients treated between 57 and 59.3 Gy, 14% for patients treated at 59.4 to 62.9 Gy, 16% for patients treated at 63 to 66 Gy and 66.1 to 73.9 Gy, and 13% for patients treated at 74 to 80 Gy (P < .0001). In multivariate analysis, the estimated HR (95% confidence interval) was 1.3 (1.1-1.6) for 57 to 59.3 Gy, 1.0 (0.9-1.2) for 59.4 to 62.9 Gy, 0.9 (0.9-1.2) for 63 to 66 Gy, 0.9 (0.8-1.1) for 66.1 to 73.9 Gy, and 1.0 (referent) for the 74 to 80 Gy cohort. There was no significant difference in the HR for the dose groups > 59.4 Gy compared with the 74 to 80 Gy cohort.

CONCLUSION

There was no improvement in OS with radiotherapy dose escalation beyond 59.4 Gy for patients with unresectable clinical stage III lung cancer treated with chemoradiation.

Bioluminescent imaging of HPV-positive oral tumor growth and its response to image-guided radiotherapy

The treatment paradigms for head and neck squamous cell cancer (HNSCC) are changing due to the emergence of human papillomavirus (HPV)-associated tumors possessing distinct molecular profiles and responses to therapy. Although patients with HNSCCs are often treated with radiotherapy, preclinical models are limited by the ability to deliver precise radiation to orthotopic tumors and to monitor treatment responses accordingly. To better model this clinical scenario, we developed a novel autochthonous HPV-positive oral tumor model to track responses to small molecules and image-guided radiation. We used a tamoxifen-regulated Cre recombinase system to conditionally express the HPV oncogenes E6 and E7 as well as a luciferase reporter (iHPV-Luc) in the epithelial cells of transgenic mice. In the presence of activated Cre recombinase, luciferase activity, and by proxy, HPV oncogenes were induced to 11-fold higher levels. In triple transgenic mice containing the iHPV-Luc, K14-CreER(tam), and LSL-Kras transgenes, tamoxifen treatment resulted in oral tumor development with increased bioluminescent activity within 6 days that reached a maximum of 74.8-fold higher bioluminescence compared with uninduced mice. Oral tumors expressed p16 and MCM7, two biomarkers associated with HPV-positive tumors. After treatment with rapamycin or image-guided radiotherapy, tumors regressed and possessed decreased bioluminescence. Thus, this novel system enables us to rapidly visualize HPV-positive tumor growth to model existing and new interventions using clinically relevant drugs and radiotherapy techniques.

Preferential cytotoxicity of bortezomib toward hypoxic tumor cells via overactivation of endoplasmic reticulum stress pathways

Hypoxia is a dynamic feature of the tumor microenvironment that contributes to drug resistance and cancer progression. We previously showed that components of the unfolded protein response (UPR), elicited by endoplasmic reticulum (ER) stress, are also activated by hypoxia in vitro and in vivo animal and human patient tumors. Here, we report that ER stressors, such as thapsigargin or the clinically used proteasome inhibitor bortezomib, exhibit significantly higher cytotoxicity toward hypoxic compared with normoxic tumor cells, which is accompanied by enhanced activation of UPR effectors in vitro and UPR reporter activity in vivo. Treatment of cells with the translation inhibitor cycloheximide, which relieves ER load, ameliorated this enhanced cytotoxicity, indicating that the increased cytotoxicity is ER stress-dependent. The mode of cell death was cell type-dependent, because DLD1 colorectal carcinoma cells exhibited enhanced apoptosis, whereas HeLa cervical carcinoma cells activated autophagy, blocked apoptosis, and eventually led to necrosis. Pharmacologic or genetic ablation of autophagy increased the levels of apoptosis. These results show that hypoxic tumor cells, which are generally more resistant to genotoxic agents, are hypersensitive to proteasome inhibitors and suggest that combining bortezomib with therapies that target the normoxic fraction of human tumors can lead to more effective tumor control.