Chest wall toxicity after stereotactic radiation in early lung cancer: a systematic review

Dosimetric investigation of couch rotation angles in non-coplanar VMAT plans for lung cancer SBRT

Background

This study aimed to investigate the effect of couch rotation angles on non-coplanar volumetric modulated arc therapy (ncVMAT) plan for stereotactic body radiotherapy (SBRT) in lung cancer patients and to evaluate the feasibility of clinically applying ncVMAT for SBRT.

Methods

Twenty-four lung cancer patients with a single lesion eligible for SBRT were enrolled in the study. Seven dual partial-arc VMAT plans with varying couch angles were designed for every patient. These plans utilized two partial arcs, with the same first arc set at a fixed 0° couch angle in all plans. The second arc's couch angle varies at 15° intervals, ranging from 0° to 90°. The plans are designated as C0, NC15, NC30, NC45, NC60, NC75, and NC90, respectively. Plan evaluation included assessment of the maximum dose (Dmax), the mean dose (Dmean), homogeneity index (HI), conformity index (CI), and the ratio of the 50% isodose volume to the planning target volume (R50%). Dosimetric parameters for organs at risk such as the ipsilateral lung, contralateral lung, bilateral lungs, esophagus, trachea, chest wall, heart, and spinal cord were analyzed. Additionally, plan complexity-related metrics included modulation degree (MD), delivery time (DT), and monitor unit (MU) were assessed.

Results

As the couch rotation angle increased, parameters such as Dmax, Dmean, HI, CI, R50%, V20Gy, V25.75Gy and V30Gy of the ipsilateral lung and bilateral lungs, V10Gy of the contralateral lung and Dmean of the chest wall varied, while MD, MU, and DT increased. Compared to C0, the Dmax, Dmean, and HI of the planning target volume (PTV) decreased from 6728.35 ± 209.56cGy, 5743.04 ± 93.45cGy, and 0.281 ± 0.032 to 6500.48 ± 225.26cGy, 5654.81 ± 109.23cGy, and 0.245 ± 0.031, respectively, when the couch was rotated to 90°. The CI increased from 0.859 ± 0.031 to 0.876 ± 0.024. Decreases in R50% were 1.4%, 4.9%, 9%, 13.5%, 16.8%, and 18.4% for NC15, NC30, NC45, NC60, NC75, and NC90, respectively.

Conclusions

In the treatment of lung cancer using SBRT, ncVMAT plans demonstrate superior dose distribution and deliver lower doses to certain OARs compared to cVMAT plans. This advantage becomes more pronounced with increasing couch rotation angles. Our study offers theoretical support for the preferential use of ncVMAT plans in lung cancer SBRT and provides empirical evidence to guide the selection of optimal couch rotation angles.

Cumulative rib fracture risk after stereotactic body radiotherapy in patients with localized non-small cell lung cancer

INTRODUCTION

Rib fracture is a known complication after stereotactic body radiotherapy (SBRT). Patient-related parameters are essential to provide patient-tailored risk estimation, however, their impact on rib fracture is less documented compared to dosimetric parameters. This study aimed to predict the risk of rib fractures in patients with localized non-small cell lung cancer (NSCLC) post-SBRT based on both patient-related and dosimetric parameters with death as a competing risk.

MATERIALS AND METHODS

In total, 602 patients with localized NSCLC treated with SBRT between 2010-2020 at Odense University Hospital, Denmark were included. All patients received SBRT with 45-66 Gray (Gy)/3 fractions. Rib fractures were identified in CT-scans using a word embedding model. The cumulative incidence function was based on cause-specific Cox hazard models with variable selection based on cross-validation model likelihood performed using 50 bootstraps.

RESULTS

In total, 19 % of patients experienced a rib fracture. The cumulative risk of rib fracture increased rapidly from 6-54 months post-SBRT. Female gender, bone density, near max dose to the rib, V30 and V40 to the rib, gross tumor volume, and mean lung dose were significantly associated with rib fracture risk in univariable analysis. The final multi-variable model consisted of V20 and V30 to the rib and mean lung dose.

CONCLUSION

Female gender and low bone density in male patients are significant predictors of rib fracture risk. The final model predicting cumulative rib fracture risk of 19 % in patients with localized NSCLC treated with SBRT contained no patient-related parameters, suggesting that dosimetric parameters are the primary drivers.

A bone tumor-like chest wall mass lesion with pathological rib fractures observed 13 years after lung stereotactic body radiotherapy: A case report

Although stereotactic body radiotherapy (SBRT) is a curative treatment option for stage I non-small cell lung cancer (NSCLC), limited data are available regarding chest wall (CW) toxicities during an extended follow-up of over 10 years. We report an unusual case of a bone tumor-like CW mass lesion with pathological rib fractures observed 13 years after SBRT for peripheral lung cancer. Despite the initial suspicion of radiation-induced sarcoma, a subsequent incisional biopsy revealed no evidence of malignancy, and a definitive diagnosis of osteonecrosis was made. Thus, long-term observation of over 10 years is required to identify late chronic complications following SBRT.

Pathophysiology and Management of Chest Wall Pain after Surgical and Non-Surgical Local Therapies for Lung Cancer

Chest wall pain syndromes can emerge following local therapies for lung cancer and can adversely affect patients' quality-of-life. This can occur after lung surgery, radiation therapy, or percutaneous image-guided thermal ablation. This review describes the multifactorial pathophysiology of chest wall pain syndromes that develop following surgical and non-surgical local therapies for lung cancer and summarizes evidence-based management strategies for inflammatory, neuropathic, myofascial, and osseous pain. It discusses a step-wise approach to treating chest wall pain that begins with non-opioid oral analgesics and includes additional pharmacologic treatments as clinically indicated, such as anticonvulsants, serotonin and norepinephrine reuptake inhibitors, tricyclic antidepressants, and various topical treatments. For myofascial pain, physical medicine techniques, such as acupuncture, trigger point injections, deep tissue massage, and intercostal myofascial release can also offer pain relief. For severe or refractory cases, opioid analgesics, intercostal nerve blocks, or intercostal nerve ablations may be indicated. Fortunately, palliation of treatment-related chest wall pain syndromes can be managed by most clinical providers, regardless of the type of local therapy utilized for a patient's lung cancer treatment. In cases where a patient's pain fails to respond to initial medical management, clinicians can consider referring to a pain specialist who can tailor a more specific pharmacologic approach or perform a procedural intervention to relieve pain.

Secretory factors released from high dose radiation-activated osteoclasts increase the expression level of pain-associated neuropeptides in sensory neuronal cultures

Stereotactic Body Radiation Therapy for lung tumors near the chest wall often causes significant chest wall pain (CWP), negatively impacting patients' quality of life. The mechanisms behind SBRT-induced CWP remain unclear and may involve multiple factors. We investigated the potential crosstalk between radiation-activated osteoclasts and sensory neurons, focusing on osteoclast-derived factors in CWP. Using the murine pre-osteoclast cell line Raw264.7, we induced differentiation with RANKL, followed by 10Gy gamma-irradiation. Conditioned media from these irradiated osteoclasts was used to treat sensory neuronal cultures from mouse dorsal root ganglia. Neuronal cultures were also directly exposed to 10Gy radiation, with and without osteoclast co-culture. Analysis of osteoclast markers and pain-associated neuropeptides was conducted using RT-qPCR and histochemical staining. Osteoclast differentiation and activity were inhibited using Osteoprotegerin and risedronate. Results showed that high-dose radiation significantly increased osteoclast size, resorption pit size, and activity biomarkers. Neurons treated with CM from irradiated osteoclasts showed increased expression of pain-associated neuropeptides CGRP and Substance P, which was mitigated by osteoprotegerin and risedronate. This study suggests that high-dose radiation enhances osteoclast activity, upregulating pain-associated neuropeptides in sensory neurons, and that inhibitors like osteoprotegerin and risedronate may offer therapeutic strategies for managing radiation-induced pain.

The effects of high-dose radiation therapy on bone: a scoping review

PURPOSE

This scoping review presents the preclinical and clinical data on the effects of high-dose radiation therapy (RT) on bone structure and function.

MATERIALS AND METHODS

An extensive PubMed search was performed for the relevant questions. The data were then synthesized into a comprehensive summary of the available relevant in-vitro, preclinical and clinical literature.

RESULTS

In-vitro studies of high-dose RT on cell cultures show considerable damage in the viability and functional capacity of the primary cells of the bones; the osteoclasts, the osteoblasts, and the osteocytes. In-vivo animal models show that high-dose RT induces significant morphological changes to the bone, inhibits the ability of bone to repair damage, and increases the fragility of the bone. Clinical data show that there is an increasing risk over time of damage to the bone, such as fractures, after high-dose RT.

CONCLUSION

These findings suggest that there may be a limit to the safe dose for single-fraction RT, and the long-term consequences of high-dose RT for the patients must be considered.

Advanced navigation technology enables endobronchial brachytherapy for peripheral lung cancer: An old technique plays a new role

PURPOSE

To investigate the feasibility of super-selectively endobronchial brachytherapy in the treatment of peripheral lung cancer guided by advanced navigation technology.

METHODS AND MATERIALS

Six patients with peripheral lung tumors successfully underwent treatment with super-selectively endobronchial brachytherapy guided by advanced navigation technology following pathway planning and were subsequently followed up to assess survival and treatment-related toxicities.

RESULTS

The endobronchial applicators were successfully placed inside the tumors of all patients using advanced navigation techniques according to the pretreatment plan, and brachytherapy was delivered at curative doses after evaluation using radiotherapy planning software. None of the patients showed local progression of the treated lesions during the follow-up for a duration ranging from 11 months to 35 months, with a median follow-up time of 23 months. The patient with the longest follow-up, nearly 3 years, exhibited a stable condition. After undergoing endobronchial brachytherapy, patients predominantly experienced localized fibrosis as indicated. No significant alterations in cardiopulmonary function were detected during the follow-up, and no other adverse effects were found.

CONCLUSIONS

The use of endobronchial brachytherapy for the curative treatment of peripheral lung cancers is feasible. Furthermore, the development of novel bronchial navigation techniques has the potential to broaden the application of endobronchial brachytherapy.

A Case of Radiation-Associated Vertebral Compression Fracture Mimicking Solitary Bone Metastasis of Lung Cancer

Radiation therapy plays an important role in the treatment of lung cancer. Although adverse effects of radiation are well known, they are sometimes difficult to be diagnosed. We report a case of a radiation-associated vertebral compression fracture which mimicked bone metastasis of lung cancer. The patient was a 57-year-old man diagnosed with lung squamous cell carcinoma (cT1aN2M0, c-stage IIIA). He received concurrent chemoradiotherapy (CRT) in combination with 6 weeks of weekly carboplatin plus paclitaxel and thoracic radiation of 60 Gy/30 fractions, followed by bi-weekly durvalumab for 12 months. On the last day of the 12-month durvalumab regimen, he complained of backache. Magnetic resonance imaging showed compression fracture of the seventh thoracic vertebra with the spinal cord compressed, and fluorine-18 fluorodeoxyglucose positron emission tomography and computed tomography demonstrated weak focal uptake only at the seventh thoracic vertebra. Although the fracture had been suspected to be bone metastasis, surgical biopsy revealed no evidence of malignancy. Since the seventh thoracic vertebra was included in the irradiation area, the patient was diagnosed with a radiation-associated fracture. Dual-energy X-ray absorptiometry of the lumbar vertebrae (L2 - 4) after the surgery revealed osteopenia. In conclusion, we successfully diagnosed the radiation-associated vertebral fracture caused by radical CRT. The fracture mimicked bone metastasis in preoperative imaging tests. Thus, surgical biopsy was useful for diagnosis.

A strategy to reduce fraction number in peripheral lung stereotactic ablative body radiotherapy

Background and purpose

Hypo-fractionated lung Stereotactic Ablative Body Radiotherapy (SABR) has often been avoided when tumours are close to the chest wall. Our strategic objective was the reduction of fraction number, while maintaining target biological effective dose coverage without increasing chest wall toxicity (CWT) predictors.

Materials and methods

Twenty previously treated lung SABR patients were stratified into four cohorts according to distance from PTV to the chest wall, <1 cm, <0.5 cm, overlapping up to 0.5 cm and 1.0 cm. For each patient, four plans were created; a chest wall optimised plan for 54 Gy in 3 fractions, the clinical plan re-prescribed for 55 Gy in 5, 48 Gy in 3 and 45 Gy in 3 fractions.

Results

For a PTV distance of 0.5-0.0 cm, a reduction of the median (range) D_max from 55.7 (57.5-54.1) Gy to 40.0 (37.1-42.0 Gy) Gy was observed for the chest wall optimised plans. The median V_30Gy decreased from 18.9 (9.7-25.6) cm³ to 3.1 (1.8-4.5) cm³. For a PTV overlap of up to 0.5 cm, the D_max reduced from 66.5 (64.1-70) Gy to 53.2 (50.6-55.1) Gy. The V_30Gy decreased from 21.5 (16.5-29.5) cm³ to 14.9 (11.3-20.2) cm³. For the cohort with up to 1.0 cm overlap, there was a reduction in D_max values of 9.9 Gy. The V_30Gy for clinical plans, at 66.8 (18.7-188.8) cm³, decreased to 55.3 (15.5-149) cm³.

Conclusion

When PTVs are within 0.5 cm of chest wall, lung SABR dose heterogeneity can be used to reduce fraction number without increasing CWT predictors.

Mistaken Metastasis: Radiation-Induced Rib Fracture Mimicking Malignancy on Computerized Tomography Case Report

A 62-year-old woman with a 40-pack-year smoking history and severe chronic obstructive pulmonary disease with early-stage right upper lobe non-small cell lung cancer (NSCLC) was treated with stereotactic ablative radiotherapy (SABR). Two years after treatment, a surveillance computerized tomography scan showed lesions of the posterior 4th and 5th ribs including expansion of the medulla that was unusual and of concern for possible malignant infiltration. A follow-up magnetic resonance imaging (MRI) scan revealed these lesions to be healing fractures post-radiotherapy. Although generally well tolerated, SABR is known to produce inflammatory and fibrotic changes both in-field and in organs at risk, and rib fractures are a well-established adverse event. MRI has high diagnostic accuracy and sensitivity for rib fractures and was able to rule out malignant spread. This case demonstrates the need for regular follow-up following SABR for early-stage NSCLC, as well as the challenge of interpreting indeterminate post-SABR radiography findings.

A pictorial essay on radiological changes after stereotactic body radiation therapy for lung tumors

Stereotactic body radiation therapy (SBRT) is a frequently used modality for the treatment of early stage non-small cell lung cancer and oligometastatic disease of the lung. The radiological changes observed in the lung after SBRT are likely to differ from those observed after conventional thoracic radiation therapy, primarily due to the small size of the target volume and highly conformal dose distributions with steep dose gradients from the target to surrounding normal lung tissues used in SBRT. Knowledge of the radiological changes that can occur after SBRT is required to correctly diagnose local failure. Herein, I report several radiological changes specific to SBRT that have been observed.

Fracture risk following stereotactic body radiotherapy for long bone metastases

BACKGROUND

Stereotactic body radiotherapy is a new treatment modality for long bone metastasis and has not been discussed in literature. We aimed to clarify stereotactic body radiotherapy outcomes for long bone metastases.

METHODS

Data of patients receiving stereotactic body radiotherapy for long bone metastases (July 2016-November 2020) were retrospectively reviewed. The prescribed dose was 30 or 35 Gy in five fractions. The endpoints were local failure and adverse effects. Local failure was defined as radiological tumor growth within the irradiation field. Adverse effects were evaluated according to the National Cancer Institute Common Terminology Criteria for Adverse Events, version 5.

RESULTS

Nineteen osseous lesions in 17 patients were assessed. The target lesions included 13 femoral, 4 humeral and 2 radial lesions. The median follow-up duration was 14 (range, 3-62) months. The 12- and 18-month local failure rates were 0 and 11%, respectively. Following 2 and 46 months of stereotactic body radiotherapy, two lesions (11%) resulted in painful femoral fractures (grade 3). Both patients underwent bipolar hip arthroplasty and could walk normally after surgery. In the late phase, one patient developed radiculopathy (almost complete paralysis of grasp) and another developed grade 2 limb edema. Other grade 2 or more severe acute and late toxicities were not observed during the follow-up period.

CONCLUSIONS

Stereotactic body radiotherapy for long bone metastases achieved excellent local control and caused two femoral fractures. We argue that stereotactic body radiotherapy for curative intent should not be contraindicated in long bone oligometastasis because fractures do not directly contribute to life expectancy.