Stereotactic Radiation for Lung Cancer: A Practical Approach to Challenging Scenarios

Incorporating the inflammation-related parameters enhances the performance of the nomogram for predicting local control in lung cancer patients treated with stereotactic body radiation therapy

PURPOSE

The study aims to investigate whether including the inflammation-related parameters would enhance the accuracy of a nomogram for local control (LC) prediction in lung cancer patients undergoing stereotactic body radiation therapy (SBRT).

METHODS

158 primary or metastatic lung cancer patients treated with SBRT were retrospectively analyzed. The clinical, dosimetric and inflammation-related parameters were collected for the Cox regression analysis. The ACPB model was constructed by employing the clinical and dosimetric factors. And the ACPBLN model was established by adding the inflammation-related factors to the ACPB model. The two models were compared in terms of ROC, Akaike Information Criterion (AIC), C-index, time-dependent AUC, continuous net reclassification index (NRI), integrated discrimination improvement (IDI), calibration plots and decision curve analysis (DCA).

RESULTS

Multivariate Cox regression analysis revealed that six prognostic factors were independently associated with LC, including age, clinical stage, planning target volume (PTV) volume, BED of the prescribed dose (BEDPD), the lymphocyte count and neutrocyte count. The ACPBLN model performed better in AIC, bootstrap-corrected C-index, time-dependent AUC, NRI and IDI than the ACPB model. The calibration plots showed good consistency between the probabilities and observed values in the two models. The DCA curves showed that the ACPBLN nomogram had higher overall net benefit than the ACPB model across a majority of threshold probabilities.

CONCLUSION

The inflammation-related parameters were associated with LC for lung cancer patients treated with SBRT. The inclusion of the inflammation-related parameters improved the predictive performance of the nomogram for LC prediction.

Tumor-associated macrophages in non-small-cell lung cancer: From treatment resistance mechanisms to therapeutic targets

Non-small cell lung cancer (NSCLC) remains one of the leading causes of cancer-related deaths worldwide. Different treatment approaches are typically employed based on the stage of NSCLC. Common clinical treatment methods include surgical resection, drug therapy, and radiation therapy. However, with the introduction and utilization of immune checkpoint inhibitors, cancer treatment has entered a new era, completely revolutionizing the treatment landscape for various cancers and significantly improving overall patient survival. Concurrently, treatment resistance often poses a critical challenge, with many patients experiencing disease progression following an initial response due to treatment resistance. Increasing evidence suggests that the tumor microenvironment (TME) plays a pivotal role in treatment resistance. Tumor-associated macrophages (TAMs) within the TME can promote treatment resistance in NSCLC by secreting various cytokines activating signaling pathways, and interacting with other immune cells. Therefore, this article will focus on elucidating the key mechanisms of TAMs in treatment resistance and analyze how targeting TAMs can reduce the levels of treatment resistance in NSCLC, providing a comprehensive understanding of the principles and approaches to overcome treatment resistance in NSCLC.

Cutting-Edge Therapies for Lung Cancer

Lung cancer remains a formidable global health challenge that necessitates inventive strategies to improve its therapeutic outcomes. The conventional treatments, including surgery, chemotherapy, and radiation, have demonstrated limitations in achieving sustained responses. Therefore, exploring novel approaches encompasses a range of interventions that show promise in enhancing the outcomes for patients with advanced or refractory cases of lung cancer. These groundbreaking interventions can potentially overcome cancer resistance and offer personalized solutions. Despite the rapid evolution of emerging lung cancer therapies, persistent challenges such as resistance, toxicity, and patient selection underscore the need for continued development. Consequently, the landscape of lung cancer therapy is transforming with the introduction of precision medicine, immunotherapy, and innovative therapeutic modalities. Additionally, a multifaceted approach involving combination therapies integrating targeted agents, immunotherapies, or traditional cytotoxic treatments addresses the heterogeneity of lung cancer while minimizing its adverse effects. This review provides a brief overview of the latest emerging therapies that are reshaping the landscape of lung cancer treatment. As these novel treatments progress through clinical trials are integrated into standard care, the potential for more effective, targeted, and personalized lung cancer therapies comes into focus, instilling renewed hope for patients facing challenging diagnoses.

And Yet It Moves: Clinical Outcomes and Motion Management in Stereotactic Body Radiation Therapy (SBRT) of Centrally Located Non-Small Cell Lung Cancer (NSCLC): Shedding Light on the Internal Organ at Risk Volume (IRV) Concept

The internal organ at risk volume (IRV) concept might improve toxicity profiles in stereotactic body radiation therapy (SBRT) for non-small cell lung cancer (NSCLC). We studied (1) clinical aspects in central vs. peripheral tumors, (2) the IRV concept in central tumors, (3) organ motion, and (4) associated normal tissue complication probabilities (NTCPs). We analyzed patients who received SBRT for NSCLC (clinical aspects, n = 78; motion management, n = 35). We found lower biologically effective doses, larger planning target volume sizes, higher lung doses, and worse locoregional control for central vs. peripheral tumors. Organ motion was greater in males and tall patients (bronchial tree), whereas volume changes were lower in patients with a high body mass index (BMI) (esophagus). Applying the IRV concept (retrospectively, without new optimization), we found an absolute increase of >10% in NTCPs for the bronchial tree in three patients. This study emphasizes the need to optimize methods to balance dose escalation with toxicities in central tumors. There is evidence that organ motion/volume changes could be more pronounced in males and tall patients, and less pronounced in patients with higher BMI. Since recent studies have made efforts to further subclassify central tumors to refine treatment, the IRV concept should be considered for optimal risk assessment.

Understanding experiences of cancer-related fatigue in patients with lung cancer after their cancer treatment: a qualitative content analysis

PURPOSE

Cancer-related fatigue (CRF) is an important symptom affecting the quality of life of patients with lung cancer. However, research on the characteristics of CRF in lung cancer and their relationship to cancer treatment is limited. We aimed to explore the unique features of CRF in patients with lung cancer, and investigate the influencing factors.

METHODS

Semi-structured interviews were conducted with 21 adult patients with lung cancer until data saturation was reached. The collected data were analyzed using qualitative content analysis. An inductive coding process and deductive content analysis incorporating the established CRF domains were employed. Patient data from electronic medical records were used for data triangulation.

RESULTS

The analysis revealed five themes of CRF: (1) energy depletion, the double burden of illness and treatment, and daily life impediments; (2) feeling down and anxious; (3) neurovascular disturbances and changes in sensory perception; (4) cognitive impairment; and (5) personal and social isolation. CRF tended to improve over time, except for persistent emotional fatigue beyond 6 months. Patients who underwent surgery followed by adjuvant cancer treatment exhibited the most diverse CRF symptoms. The concurrent chemoradiation therapy group experienced significant physical fatigue, whereas the radiosurgery group reported distinct emotional fatigue. Certain factors, such as exercise, can serve as both alleviating and aggravating factors for CRF.

CONCLUSION

Tailored interventions that take into account the multidimensional symptoms of CRF and patient characteristics are crucial. These findings will guide healthcare professionals when implementing patient-centered symptom management and patient education.

Reirradiation with stereotactic body radiotherapy for primary or secondary lung malignancies: Tumor control probability and safety analyses

BACKGROUND

Reirradiation with stereotactic body radiotherapy (SBRT) for patients with primary or secondary lung malignancies represents an appealing definitive approach, but its feasibility and safety are not well defined. The purpose of this study was to investigate the tumor control probability (TCP) and toxicity for patients receiving reirradiation with SBRT.

PATIENTS AND METHODS

Eligible patients with recurrence of primary or secondary lung malignancies from our hospital were subjected to reirradiation with SBRT, and PubMed- and Embase-indexed articles were reviewed. The patient characteristics, pertinent SBRT dosimetric details, local tumor control, and toxicities were extracted. The logistic dose-response models were compared for TCP and overall survival (OS) in terms of the physical dose and three-, four-, and five-fraction equivalent doses.

RESULTS

The data of 17 patients from our hospital and 195 patients extracted from 12 articles were summarized. Reirradiation with SBRT yielded 2-year estimates of 80% TCP for doses of 50.10 Gy, 55.85 Gy, and 60.54 Gy in three, four, and five fractions, respectively. The estimated TCP with common fractionation schemes were 50%, 60%, and 70% for 42.04 Gy, 47.44 Gy, and 53.32 Gy in five fractions, respectively. Similarly, the 2-year estimated OS was 50%, 60%, and 70% for 41.62 Gy, 46.88 Gy, and 52.55 Gy in five fractions, respectively. Central tumor localization may be associated with severe toxicity.

CONCLUSIONS

Reirradiation with SBRT doses of 50-60 Gy in 3-5 fractions is feasible for appropriately selected patients with recurrence of peripheral primary or secondary lung malignancies, but should be carefully considered for centrally-located tumors due to potentially severe toxicity. Further studies are warranted for optimal dose/fractionation schedules and more accurate selection of patients suitable for reirradiation with SBRT.

Stereotactic body radiotherapy for Ultra-Central lung Tumors: A systematic review and Meta-Analysis and International Stereotactic Radiosurgery Society practice guidelines

BACKGROUND

Stereotactic body radiotherapy (SBRT) is an effective and safe modality for early-stage lung cancer and lung metastases. However, tumors in an ultra-central location pose unique safety considerations. We performed a systematic review and meta-analysis to summarize the current safety and efficacy data and provide practice recommendations on behalf of the International Stereotactic Radiosurgery Society (ISRS).

METHODS

We performed a systematic review using PubMed and EMBASE databases of patients with ultra-central lung tumors treated with SBRT. Studies reporting local control (LC) and/or toxicity were included. Studies with <5 treated lesions, non-English language, re-irradiation, nodal tumors, or mixed outcomes in which ultra-central tumors could not be discerned were excluded. Random-effects meta-analysis was performed for studies reporting relevant endpoints. Meta-regression was conducted to determine the effect of various covariates on the primary outcomes.

RESULTS

602 unique studies were identified of which 27 (one prospective observational, the remainder retrospective) were included, representing 1183 treated targets. All studies defined ultra-central as the planning target volume (PTV) overlapping the proximal bronchial tree (PBT). The most common dose fractionations were 50 Gy/5, 60 Gy/8, and 60 Gy/12 fractions. The pooled 1- and 2-year LC estimates were 92 % and 89 %, respectively. Meta-regression identified biological effective dose (BED10) as a significant predictor of 1-year LC. A total of 109 grade 3-4 toxicity events, with a pooled incidence of 6 %, were reported, most commonly pneumonitis. There were 73 treatment related deaths, with a pooled incidence of 4 %, with the most common being hemoptysis. Anticoagulation, interstitial lung disease, endobronchial tumor, and concomitant targeted therapies were observed risk factors for fatal toxicity events.

CONCLUSION

SBRT for ultra-central lung tumors results in acceptable rates of local control, albeit with risks of severe toxicity. Caution should be taken for appropriate patient selection, consideration of concomitant therapies, and radiotherapy plan design.

Outcomes Following SBRT vs. IMRT and 3DCRT for Older Patients with Stage IIA Node-Negative Non-Small Cell Lung Cancer > 5 cm

BACKGROUND

To describe outcomes and compare the effectiveness of stereotactic body radiotherapy (SBRT) versus 3-dimensional conformal radiotherapy (3DCRT) or intensity-modulated radiotherapy (IMRT) in patients with stage IIA lymph node-negative (N0) non-small cell lung cancer (NSCLC) tumors > 5 cm.

METHODS

We used the SEER-Medicare database (2005-2015) to identify patients > 65 years with stage IIA (AJCC TNM7) N0 NSCLC > 5 cm tumors who were treated with SBRT, IMRT, and 3DCRT. We used propensity score methods with inverse probability weighting to compare lung cancer-specific survival (LCSS), overall survival (OS), and toxicity.

RESULTS

Of 584 patients, 88 (15%), 140 (24%), and 356 (61%) underwent SBRT, IMRT, and 3DCRT, respectively. The SBRT group was older (P = .004), had more comorbidities (P = .02), smaller tumors (P = .03), and more adenocarcinomas (P < .0001). We found a trend towards higher median unadjusted OS with SBRT compared to IMRT and 3DCRT (19 vs. 13 and 14 months, respectively, P = .37). In our propensity score-adjusted analyses, SBRT was significantly associated with better OS and LCSS compared to IMRT (HR_OS: 0.78, 95% CI: 0.68-0.89, HR_LCSS: 0.70, 95% CI: 0.60-0.81) and 3DCRT (HR_OS: 0.81, 95% CI: 0.72-0.93, HR_LCSS: 0.80, 95% CI: 0.68-0.93). SBRT-treated patients also had lower overall adjusted complication rates compared to IMRT (OR: 0.74, 95% CI: 0.55-0.99) and 3DCRT (OR: 0.53, 95% CI: 0.40-0.71).

CONCLUSION

For patients with NSCLC tumors > 5 cm, SBRT trends towards fewer toxicities and improved survival compared to other forms of radiotherapy. Our findings support SBRT as an appropriate treatment strategy for older patients with larger inoperable NSCLC tumors.

Histone deacetylase inhibitors as sanguine epitherapeutics against the deadliest lung cancer

The back-breaking resistance mechanisms generated by lung cancer cells against epidermal growth factor receptor (EGFR), KRAS and Janus kinase 2 (JAK2) directed therapies strongly prioritizes the requirement of novel therapies which are perfectly tolerated, potentially cytotoxic and can reinstate the drug-sensitivity in lung cancer cells. Enzymatic proteins modifying the post-translational modifications of nucleosome-integrated histone substrates are appearing as current targets for defeating various malignancies. Histone deacetylases (HDACs) are hyperexpressed in diverse lung cancer types. Blocking the active pocket of these acetylation erasers through HDAC inhibitors (HDACi) has come out as an optimistic therapeutic recourse for annihilating lung cancer. This article in the beginning gives an overview about lung cancer statistics and predominant lung cancer types. Succeeding this, compendium about conventional therapies and their serious drawbacks has been provided. Then, connection of uncommon expression of classical HDACs in lung cancer onset and expansion has been detailed. Moreover, keeping the main theme in view this article deeply discusses HDACi in the context of aggressive lung cancer as single agents and spotlights various molecular targets suppressed or induced by these inhibitors for engendering cytotoxic effect. Most particularly, the raised pharmacological effects achieved on using these inhibitors in concerted form with other therapeutic molecules and the cancer-linked pathways altered by this procedure are described. The positive direction towards further heightening of efficacy and the pressing requirement of exhaustive clinical assessment has been proposed as a new focus point.

Adverse Events Following Limited Resection versus Stereotactic Body Radiation Therapy for Early Stage Lung Cancer

Rationale: Approximately a quarter of patients with early stage lung cancer are not medically fit for lobectomy. Limited resection and stereotactic body radiation therapy (SBRT) have emerged as alternatives for these patients. Given the equipoise on the effectiveness of the two treatments, treatment-related adverse events (AEs) could have a significant impact on patients' decision-making and treatment outcomes. Objectives: To compare the AE profile between SBRT versus limited resection. Methods: Data were derived from a prospective cohort of patients with stage I-IIA non-small cell lung cancer who were deemed as high-risk for lobectomy recruited from five centers across the United States. Propensity scores and inverse probability weighting were used to compare the rates of 30- and 90-day AEs among patients treated with limited resection versus SBRT. Results: Overall, 65% of 252 patients underwent SBRT. After adjusting for propensity scores, there was no significant difference in developing at least one AE comparing SBRT to limited resection (odds ratio [OR]: 1.00; 95% confidence interval [CI]: 0.65-1.55 and OR: 1.27; 95% CI: 0.84-1.91 at 30 and 90 days, respectively). SBRT was associated with lower risk of infectious AEs than limited resection at 30 days (OR: 0.05; 95% CI: 0.01-0.39) and 90 days posttreatment (OR: 0.41; 95% CI: 0.17-0.98). Additionally, SBRT was associated with persistently elevated risk of fatigue (OR: 2.47; 95% CI: 1.34-4.54 at 30 days and OR: 2.69; 95% CI: 1.52-4.77 at 90 days, respectively), but significantly lower risks of respiratory AEs (OR: 0.36; 95% CI: 0.20-0.65 and OR: 0.51; 95% CI: 0.31-0.86 at 30 and 90 days, respectively). Conclusions: Though equivalent in developing at least one AE, we found that SBRT is associated with less toxicity than limited resection in terms of infectious and respiratory AEs but higher rates of fatigue that persisted up to 3 months posttreatment. This information, combined with data about oncologic effectiveness, can help patients' decision-making regarding these alternative therapies.

Near-infrared Nrf2 activator IR-61 dye alleviates radiation-induced lung injury

Oxidative stress injury and subsequent inflammatory response are considered to play critical roles in radiation-induced lung injury (RILI). Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor that regulates oxidative stress response and represses inflammation, but its therapeutic value in RILI remains elusive. Our previous studies have shown that the near-infrared (NIR) IR-61 dye evokes intracellular antioxidant defence by enhancing Nrf2 signalling and promoting anti-inflammatory effects. We established a model of RILI in mice exposed to whole-thoracic irradiation. The results showed that IR-61 treatment notably improved pulmonary functions by decreasing lung density and diminishing airway resistance. In addition, IR-61 significantly ameliorated radiation-induced inflammatory cell infiltration and proinflammatory cytokine (IL-1β, IL-6 and TNF-α) release, thereby mitigating inflammatory response. Furthermore, IR-61 mitigated radiation-induced lung fibrosis by decreasing the collagen deposition and the levels of fibrogenesis-related factors (collagen I, collagen III, α-SMA, and fibronectin). More importantly, IR-61 was found to accumulate in the mitochondria of macrophages in irradiated lung tissues. Therefore, the functions of IR-61 in macrophages were further studied in irradiated macrophage cell lines, MH-s and RAW 264.7 in vitro. The results indicated that IR-61 upregulated the expression of Nrf2 and haem oxygenase-1(HO-1) and decreased the levels of reactive oxygen species (ROS) and pro-inflammatory cytokines (IL-1β and IL-6) in macrophages after radiation. In summary, our study suggests that IR-61 effectively mitigates RILI by activating Nrf2 signalling in irradiated lung tissues. In particular, Nrf2-mediated anti-inflammatory and antioxidant effects in irradiated lung tissue macrophages play critical roles in protecting against RILI.

Sintilimab for the treatment of non-small cell lung cancer

Anti-programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) immunotherapy has dramatically changed the therapeutic landscape of inoperable non-small cell lung cancer (NSCLC), and has been included in first-line treatments. Sintilimab is a domestic anti-PD-1 monoclonal antibody in China that has received approvals from the National Medical Products Administration to treat classical Hodgkin’s lymphoma, hepatocellular carcinoma, and squamous and non-squamous NSCLC. In a prospective clinical study we led, neoadjuvant sintilimab has led to major and complete pathologic responses, which are recommended as surrogate endpoints for neoadjuvant immunotherapy; however, its effect remains inconclusive in pulmonary ground glass nodules. Meanwhile, combination plans seem more likely to be satisfying therapeutic options. Specifically, sintilimab plus platinum-based chemotherapy plans conferred better anti-tumor efficacy and clinical benefits compared to chemotherapy alone, which led to their approval in China and the acceptance of a biological license application in the US. Besides, the combination with other plans, such as docetaxel, cytokine-induced killer cell immunotherapy, radiation therapy, and anlotinib have also shown promising anti-tumor efficacy, with acceptable toxicities, and are therefore worth further exploration. In addition, several clinical trials on NSCLC at our center are ongoing. In general, sintilimab and its combinatorial plans were effective and well tolerated, but the treatment requires appropriate timing; pathologic responses can be surrogate endpoints for neoadjuvant immunotherapy, while more effective biomarkers are warranted. This study provides an overview of sintilimab-based clinical trials on NSCLC, and may support further investigation of sintilimab in future clinical trials.

Research Progress of Anti-PD-1/PD-L1 Immunotherapy Related Mechanisms and Predictive Biomarkers in NSCLC

Programmed cell death-1 (PD-1)/programmed death-ligand 1 (PD-L1) is an important pair of immune checkpoints (IC), which play an essential role in the immune escaping process of tumors. Anti-PD-1/PD-L1 immunotherapy can block the suppression effect of the immune system produced by tumor cells through the PD-1/PD-L1 axis and restore the pernicious effect of the immune system on tumor cells. The specific mechanism of anti-PD-1/PD-L1 immunotherapy is closely related to PI3K (phosphatidylinositol 3-kinase)/AKT (AKT serine/threonine kinase 1), JNK (c-Jun N-terminal kinase), NF-kB (nuclear factor-kappa B subunit 1), and other complex signaling pathways. Patients receiving anti-PD-1/PD-L1 immunotherapy are prone to drug resistance. The mechanisms of drug resistance mainly include weakening recognition of tumor antigens by immune cells, inhibiting activation of immune cells, and promoting the production of suppressive immune cells and molecules. Anti-PD-1/PD-L1 immunotherapy plays a vital role in non-small cell lung cancer (NSCLC). It is essential to find better efficacy prediction-related biomarkers and screen patients suitable for immunotherapy. At present, common biomarkers related to predicting immune efficacy mainly include PD-L1 expression level in tumors, tumor mutation burden (TMB), microsatellite instability (MSI)/mismatch repair (MMR), mutations of driver gene, etc. However, the screening efficacy of each indicator is not ideal, and the combined application of multiple indicators is currently used. This article comprehensively reviews anti-PD-1/PD-L1 immunotherapy-related mechanisms, drug resistance-related mechanisms, and therapeutic efficacy-related predictive biomarkers.

High Dose Thoracic Re-Irradiation and Chemo-Immunotherapy for Centrally Recurrent NSCLC

Simple Summary

Since the early 1980s, there has been a trend towards escalating radiation doses in pulmonary tumor recurrences with the aim of improving survival. In this context, we performed a literature search in order to summarize the evidence of curative thoracic re-irradiation for centrally recurrent lung cancer. Tumor relapse in this specific situation poses a major problem because of the proximity to mediastinal organs. Of the initial 227 studies, 11 fulfilled the inclusion criteria for this analysis. The median overall survival (mOS) was 18.1 months (range 9.3–25.1), the median progression-free survival (mPFS) was nine months (range 4.5–16), and the median locoregional control (mLRC) was 12.1 months (range 6.5–20). The total re-irradiation dose correlated with both mLRC (p-value = 0.012) and mOS (p-value = 0.007). As large-scale prospective trials in the field are missing, this literature review is primarily based on retrospective data. In today’s age of enhanced long-term survival rates after chemoradiotherapy followed by immune checkpoint inhibition, the current analysis provides valuable insights into radiation treatment options for patients with loco-regional lung cancer recurrence.

Abstract

Introduction: Thoracic re-irradiation for recurrent lung cancer dates back four decades, when the first small series on 29 patients receiving palliative doses was published. With 5-year overall survival rates of 57% in PDL-1 positive patients after primary chemo-radio-immunotherapy, the number of patients who experience loco-regional relapse will increase in the near future. In this context, centrally recurring lung tumors pose a major treatment challenge. Hence, the aim of the current review is to compile the available evidence on curatively intended thoracic re-irradiation for this special clinical situation. Methods: A systematic literature search according to the PRISMA guidelines was performed. A study was included when the following criteria were met: (1) 66% of the patients had NSCLC, (2) a total dose of 50 Gy in the second course and/or a biologically effective dose of at least 100 Gy in both treatment courses was administered, (3) re-irradiation was administered with modern radiation techniques, (4) 50% or more of the patients had a centrally located relapse, (5) the minimum cohort size was 30 patients. Results: Of the initial 227 studies, 11 were analyzed, 1 of which was prospective. Median overall survival (OS) was 18.1 months (range 9.3–25.1), median progression free survival (PFS) was nine months (range 4.5–16), and median loco-regional control (LRC) was 12.1 months (range 6.5–20). Treatment-related mortality rates ranged from 2% to 14%. The total dose at re-irradiation correlated with both LRC (p-value = 0.012) and OS (p-value = 0.007) with a close relation between these two clinical endpoints (p-value = 0.006). The occurrence of acute toxicity grade 1 to 4 depended on the PTV size at re-irradiation (p-value = 0.033). Conclusion: The evidence regarding curative re-irradiation for centrally recurrent NSCLC is primarily based on scarce retrospective data, which are characterized by a high degree of heterogeneity. The OS in this clinically challenging situation is expected to be around 1.5 years after re-treatment. Patients with a good performance score, younger age, small tumors, and a longer interval to recurrence potentially benefit most from re-irradiation. In this context, prospective trials are warranted to achieve substantial advances in the field.

Radiation-Induced Dyspnea in Lung Cancer Patients Treated with Stereotactic Body Radiation Therapy

Simple Summary

Dyspnea is a common symptomatic side-effect of thoracic radiation therapy. The aim of this study is to build a predictive model of any-grade radiation-induced dyspnea within six months after stereotactic body radiation therapy in patients treated for non-small cell lung cancer. The occurrence of pre-treatment chronic obstructive pulmonary disease and higher relative lungs volume receiving more than 15 Gy as well as heart volume were shown to be risk factors for dyspnea. The obtained results encourage further studies on the topic, which could validate the present organ-based findings and explore the voxel-based landscape of radiation dose sensitivity in the development of dyspnea.

Abstract

In this study, we investigated the prognostic factors for radiation-induced dyspnea after hypo-fractionated radiation therapy (RT) in 106 patients treated with Stereotactic Body RT for Non-Small-Cell Lung Cancer (NSCLC). The median prescription dose was 50 Gy (range: 40–54 Gy), delivered in a median of four fractions (range: 3–12). Dyspnea within six months after SBRT was scored according to CTCAE v.4.0. Biologically Effective Dose (α/β = 3 Gy) volume histograms for lungs and heart were extracted. Dosimetric parameters along with patient-specific and treatment-related factors were analyzed, multivariable logistic regression method with Leave-One-Out (LOO) internal validation applied. Model performance was evaluated by the area under the receiver operating characteristic (ROC) curve (AUC) and calibration plot parameters. Fifty-seven patients (53.8%) out of 106 developed dyspnea of any grade after SBRT (25/57 grade ≥ 2 cases). A three-variable predictive model including patient comorbidity (COPD), heart volume and the relative lungs volume receiving more than 15 Gy was selected. The model displays an encouraging performance given by a training ROC-AUC = 0.71 [95%CI 0.61–0.80] and a LOO-ROC-AUC = 0.64 [95%CI 0.53–0.74]. Further modeling efforts are needed for dyspnea prediction in hypo-fractionated treatments in order to identify patients at high risk for developing lung toxicity more accurately.