Sinoatrial Node Dose Is Associated With Worse Survival in Patients Undergoing Definitive Stereotactic Body Radiation Therapy for Central Lung Cancers

PURPOSE

Our purpose was to evaluate the clinical consequences of sinoatrial node (SAN) and atrioventricular node (AVN) irradiation in patients undergoing stereotactic body radiation therapy (SBRT) for central non-small cell lung cancer (NSCLC) tumors.

METHODS AND MATERIALS

A single-institutional retrospective review of patients with primary NSCLC undergoing definitive SBRT for centrally located thoracic tumors from February 2007 to December 2021 was performed. The SAN and AVN were contoured in accordance with a published contouring atlas, and the maximum dose (Dmax) and mean dose (Dmean) for each structure were calculated. Sequential log rank testing between the 50th and 90th percentiles was used to identify potential cutoff values for the corresponding dosimetric parameters and overall survival.

RESULTS

Among 93 eligible patients, the median age was 72.5 years (IQR, 66.6-78.3), and median follow-up was 32.4 months (IQR, 13.0-49.6). The median SAN Dmax and Dmean were 95 cGy (range, 9-5394) and 58 cGy (range, 7-3168), respectively. The median AVN Dmax and Dmean were 45 cGy (range, 4-2121) and 34 cGy (range, 3-1667), respectively. Candidate cutoff values for SAN Dmax and Dmean were 1309 and 836 cGy, respectively. No associations between AVN parameters and survival outcomes were identified. Upon multivariate Cox regression, the SAN Dmax cutoff (hazard ratio [HR], 2.03 [1.09-3.79]; P = .026) and SAN Dmean cutoff (HR, 2.22 [1.20-4.12]; P = .011) were significantly associated with overall survival. For noncancer-associated survival, the SAN Dmax cutoff trended toward significance (HR, 2.02 [0.89-4.57]; P = .092), and the SAN Dmean cutoff remained significantly associated (HR, 2.34 [1.05-5.18]; P = .037).

CONCLUSIONS

For patients undergoing SBRT for NSCLC, SAN Dmax and Dmean were significantly associated with worse overall survival using cut-off values of 1309 and 836 cGy, respectively. Further studies examining the effect of SAN irradiation during SBRT are warranted.

Long-Term Survival and Failure Outcomes of Single-Fraction Stereotactic Body Radiation Therapy in Early Stage NSCLC

Introduction

This study aims to report our 13-year institutional experience with single-fraction stereotactic body radiation therapy (SF-SBRT) for early stage NSCLC.

Methods

A single-institutional retrospective review of patients with biopsy-proven peripheral cT1-2N0M0 NSCLC undergoing definitive SF-SBRT between September 2008 and May 2022 was performed. All patients were treated to 27 Gy with heterogeneity corrections or 30 Gy without. Primary outcomes were overall survival and progression-free survival. Secondary outcomes included local failure, nodal failure, distant failure, and second primary lung cancer.

Results

Among 263 eligible patients, the median age was 76 years (interquartile range [IQR]: 70-81 y) and median follow-up time was 27.2 months (IQR: 14.25-44.9 mo). Median tumor size was 1.9 cm (IQR: 1.4-2.6 cm), and 224 (85%) tumors were T1. There were 92 patients (35%) alive at the time of analysis with a median follow-up of 34.0 months (IQR: 16.6-50.0 mo). Two- and five-year overall survival was 65% and 26%, respectively. A total of 74 patients (28%) developed disease progression. Rates of five-year local failure, nodal failure, distant failure, and second primary lung cancer were 12.7%, 14.7%, 23.5%, and 12.0%, respectively.

Conclusions

Consistent with multiple prospective randomized trials, in a large real-world retrospective cohort, SF-SBRT for peripheral early stage NSCLC was an effective treatment approach.

Sinoatrial Node Irradiation in Patients Undergoing Definitive Stereotactic Body Radiation Therapy (SBRT) for Central Lung Cancers

PURPOSE/OBJECTIVE(S)

The clinical consequences of sinoatrial node (SAN) and atrioventricular node (AVN) irradiation in patients undergoing thoracic stereotactic body radiation therapy (SBRT) remains unclear. We examined the relationship between SAN and AVN dose with survival outcomes in patients with central non-small cell lung cancer (NSCLC) tumors.

MATERIALS/METHODS

A single-institutional retrospective review of patients with primary NSCLC undergoing definitive SBRT for centrally located tumors from February 2007 to December 2021 was performed. Central tumors were defined as within 2 cm of the proximal airway, mediastinum, great vessels, or spinal cord whereas ultracentral tumors were directly abutting any of the above structures. All patients underwent five-fraction SBRT to a total dose of 50 to 60 Gy. The SAN and AVN were contoured in accordance with a published contouring atlas and the maximum dose (Dmax) and mean dose (Dmean) for each structure were calculated. Sequential log rank testing between the 50th and 90th percentiles was used to identify potential cutoff values for the corresponding dosimetric parameters and non-cancer associated survival.

RESULTS

Among 93 eligible patients, the median age was 72.5 years (Inter-Quartile Range [IQR], 66.6-78.3), median follow up was 32.4 months (IQR, 13.0-49.6), and 48 patients were female (52%). There were 49 ultracentral tumors (53%) and the median planning target volume (PTV) was 31.0 cc (IQR, 18.0-53.3). The median SAN Dmax and Dmean were 95 cGy (IQR, 37-1,072) and 58 cGy (IQR, 26-641), respectively. The median AVN Dmax and Dmean were 45 cGy (IQR, 19-506) and 34 cGy (IQR, 15-160), respectively. Candidate cutoff values for SAN Dmax and Dmean were 1,309 cGy and 814 cGy, respectively. No significant cutoff values were identified for either AVN parameter. Kaplan-Meier analysis for the proposed SAN Dmean constraint was significantly associated with overall (p = 0.016) and non-cancer associated survival (p = 0.028). The SAN Dmax constraint was significantly associated with only overall survival (p = 0.029). In a multivariate model, the SAN Dmean cutoff significantly correlated with both overall (Hazard Ratio [HR] 2.1 [1.13-3.78], p = 0.019) and non-cancer associated survival (HR 2.39 [1.12-5.10], p = 0.025) whereas the SAN Dmax cutoff was only significantly associated with overall survival (HR 1.95 [1.03-3.68], p = 0.041).

CONCLUSION

SAN Dmax and Dmean were associated with significantly worse overall survival using cut-off values of 1,309 cGy and 814 cGy, respectively. SAN dose should be considered in radiation planning and further study on the consequence of SAN irradiation during SBRT is warranted.

Brachial Plexopathy After Single-Fraction Stereotactic Body Radiation Therapy in Apical Lung Tumors

PURPOSE

The objective of this study was to evaluate the incidence of brachial plexus injury (BPI) after single-fraction stereotactic body radiation therapy (SBRT) to apical lung tumors.

METHODS AND MATERIALS

A retrospective cohort analysis was performed of all patients treated with single-fraction lung SBRT at our institution from 2007 to 2022. Apical tumors were identified as those with an epicenter located above the arch of the aorta. Dosimetric analysis of dose to the brachial plexus (BP) was done using both the subclavian vessel (SCV) surrogate structure and anatomic BP. BPI was assessed per Common Terminology Criteria for Adverse Events, version 4.0, as regional paresthesia, marked discomfort and muscle weakness, and limited movement of the arm or hand.

RESULTS

A total of 45 patients met inclusion criteria with median follow-up of 21 months. There were 9 patients who exceeded the BP dose constraint using the SCV or anatomic BP volume. Only 1 patient (2.2%) developed grade 2 BPI, occurring 7 months after SBRT. Dose to the anatomic BP for the affected patient was 26.39 Gy. For the entire cohort, the median SCV and anatomic maximum BP doses were 8.44 and 7.14 Gy, respectively.

CONCLUSIONS

There is considerable variability in dose delivered to the BP after SBRT to apical lung tumors. BPI after single-fraction SBRT to apical tumors is rare and rates are comparable with those reported with multifraction regimens.

Right Atrial Dose Is Associated with Worse Outcome in Patients Undergoing Definitive Stereotactic Body Radiation Therapy for Central Lung Tumors

Simple Summary

The clinical consequences of irradiating the cardiac substructures during stereotactic body radiation therapy (SBRT) remains unclear. We evaluated 83 lung cancer patients who underwent SBRT for early stage lung cancer. Using specialized software, we generated structures for fourteen cardiac substructures and evaluated radiation dose parameters for each. Among these parameters, the dose to 45% (D45%) of either the right atria or ventricle was associated with worse non-cancer associated survival with an identified cutoff value of 890 cGy and 564 cGy for each, respectively. Via these cutoffs, the D45% to the right atria, not the right ventricle, was associated with worse non-cancer associated and overall survival. Based on these findings, reducing the dose to the right atria during SBRT may improve patient outcomes in at risk patients.

Abstract

The consequence of cardiac substructure irradiation in patients receiving stereotactic body radiation therapy (SBRT) is not well characterized. We reviewed the charts of patients with central lung tumors managed by definitive SBRT from June 2010–April 2019. All patients were treated with five fractions, typically either 5000 cGy (44.6%) or 5500 cGy (42.2%). Via a multi-patient atlas, fourteen cardiac substructures were autosegmented, manually reviewed and analyzed using dosimetric parameters. A total of 83 patients were included with a median follow up of 33.4 months. Univariate Cox regression analysis identified a D45% dose to the right atria and ventricle for further study. Sequential log-rank testing evaluating an association between non-cancer associated survival and D45% dose to the right atria or ventricle and association was employed, identifying candidate cutoff values of 890.3 cGy and 564.4 cGy, respectively. Kaplan–Meier analysis using the reported cutoff values found the D45% right atria constraint to be significantly associated with non-cancer associated (p ≤ 0.001) and overall survival (p ≤ 0.001) but not the right ventricle constraint. Within a multivariate model, the proposed right atria D45% cutoff remained significantly correlated with non-cancer associated survival (Hazard’s Ratio (HR) ≤ 8.5, 95% confidence interval (CI) 1.1–64.5, p ≤ 0.04) and OS (HR ≤ 6.1, 95% CI 1.0–36.8, p ≤ 0.04). In conclusion, a dose to D45% of the right atria significantly correlated with outcome and the candidate constraint of 890 cGy stratified non-cancer associated and OS. The inclusion of these findings with previously characterized relationships between proximal airway constraints and survival enhances our understanding of why centrally located tumors are high risk and potentially identifies key constraints in organ at risk prioritization.

Evaluation of risk-stratification using gene expression assays in patients with breast cancer receiving neoadjuvant chemotherapy

576

Background: Among patients with hormone receptor-positive, human epidermal growth factor receptor 2 (HER2)-negative breast cancer, several prospective studies investigated various gene expression assays, such as 21-gene recurrence score (21 RS) and 70-gene signature (70 GS), to identify a subgroup of patients with pathologic complete response (pCR) from neoadjuvant chemotherapy. However, in the absence of large prospective trials to validate such findings, the National Comprehensive Cancer Network guideline does not recommend the routine adoption of such assays in the setting of neoadjuvant therapies. To address this knowledge gap, we performed an observational cohort study to compare pCR and survival outcomes based on these assays. Methods: The National Cancer Database (NCDB) was queried for female patients diagnosed between 2010 and 2017 with stage I-III breast cancer who underwent neoadjuvant chemotherapy and either 70 GS or 21 RS. Logistic multivariable analysis (MVA) was performed to identify variables associated with pCR. Cox MVA was performed to evaluate overall survival (OS). Subgroup analyses were performed among patients with favorable hormone receptor status (hormone receptor-positive, HER2-negative) and with RS ≥26 instead of RS ≥31. Results: A total of 3,009 patients met our inclusion criteria, with 2,075 (n = 1,287 for RS < 31, n = 788 for RS ≥31) and 934 (n = 175 for low risk, n = 759 for high risk) patients who underwent 21 RS and 70 GS, respectively. The median follow up was 48.0 months (interquartile range 32.2-66.7). On logistic MVA for all patients, those with a high risk from 70 GS or with RS ≥31 were more likely to have pCR. When compared to RS ≥31, a high risk from 70 GS was not associated with pCR. However, among those with favorable hormone receptor status, similar findings were noted, except that those with a high risk group from 70 GS were less likely to have pCR compared to those with RS ≥31. On Cox MVA for all patients, pCR was associated with improved OS. While RS ≥31 was associated with worse mortality, a high risk from 70 GS was not. No interaction was observed between pCR and risk groups for OS in both groups (interaction p = 0.23 for 70 GS, p = 0.66 for 21 RS). When analyses were repeated using a high risk group from 21 RS defined as RS ≥26, similar findings were noted, except that having favorable hormone receptor status and RS ≥26 was not associated with pCR when compared to the high risk from 70 GS. Conclusions: To our knowledge, this is the largest study using a nationwide oncology database suggesting that high recurrence risk groups in both assays were associated with pCR and that pCR was associated with improved survival. For those with favorable hormone receptor status, RS ≥31 may be a more selective prognostic marker. Further studies would be warranted to investigate the role of gene expression assays in the setting of neoadjuvant chemotherapy.

Racial differences and trends in pathologic complete response following neoadjuvant chemotherapy for breast cancer

575

Background: Given improvements in systemic therapy, pathologic complete response (pCR) rates following neoadjuvant chemotherapy were over 60% in breast cancer patients in recent clinical trials, especially in human epidermal growth factor receptor 2 (HER2)-positive and triple negative cases. While racial minority groups were associated with worse survival outcomes despite receiving standard of care in prospective studies, they were under-represented in clinical trials. To address this knowledge gap, we performed an observational cohort study to evaluate pCR and survival outcomes stratified by racial and ethnic groups. Methods: The National Cancer Database (NCDB) was queried for female patients with stage I-III breast cancer diagnosed between 2010 and 2017 treated with neoadjuvant chemotherapy followed by surgery. Cochran-Armitage test was used to analyze the trend of pCR over time. Logistic multivariable analysis (MVA) was used to identify variables associated with pCR defined as ypT0/isN0. Cox MVA was used to analyze the overall survival (OS) benefit. Results: A total of 105,804 patients (n = 72,631 for non-Hispanic white [NHW], n = 7,632 for Hispanic white [HW], n = 19,505 for black, n = 4,393 for Asian or Pacific Islander [API], n = 1,643 for other race) were included for analysis. Median follow up was 49.2 months (interquartile range 32.7-71.3). Overall pCR rate increased from 15.1% in 2010 to 27.2% in 2017, largely driven by API women (15.7% to 31.6%) and hormone receptor (HR)-HER2+ tumors (28.6% to 53.1%; all trend p < 0.001). On logistic MVA, when compared to NHW women, HW women were more likely to have pCR for HR-HER2+ (adjusted odds ratio [aOR] 1.18, p = 0.02) and HR+HER2+ tumors (aOR 1.29, p = 0.005), while black women were more likely to have pCR for HR+HER2- tumors (aOR 1.13, p = 0.01) and less likely for HR-HER2+ (aOR 0.80, p < 0.001) and triple negative tumors (aOR 0.82, p < 0.001). API women were more likely to have pCR for HR-HER2+ tumors compared to NHW women (aOR 1.17, p = 0.04). On Cox MVA, when compared to NHW women, HW (ypT+N0: adjusted hazards ratio [aHR] 0.75, p < 0.001; ypN+: aHR 0.79, p < 0.001) and API women (ypT0/isN0: aHR 0.52, p = 0.005; ypT+N0: aHR 0.63, p < 0.001; ypN+: aHR 0.86, p = 0.03) were associated with improved OS, while black women were associated with worse OS for ypN+ only (aHR 1.18, p < 0.001). Conclusions: To our knowledge, this is the largest study using a nationwide oncology database suggesting the improving trend of pCR rate over time for all racial cohorts. In our study, when compared to NHW, HW and API women were more likely to have pCR for select HER2+ tumors, while black women were less likely to have pCR for HR-HER2+ and triple negative tumors but not for HR+HER2- tumors. HW and API women were associated with improved survival in the setting of any residual disease compared to NHW women, while black women were associated with worse survival only for residual nodal disease.

Prior Treatment for Non-small Cell Lung Cancer Is Associated With Improved Survival in Patients who Undergo Definitive Stereotactic Body Radiation Therapy for a Subsequent Lung Malignancy: A Retrospective Multivariate and Matched Pair Analysis

BACKGROUND

Despite occurring commonly, the prognoses of second early-stage non-small cell lung cancers (NSCLC) are not well known.

METHODS

The authors retrospectively reviewed the charts of inoperable patients who underwent thoracic stereotactic body radiation therapy (SBRT) from February 2007 to April 2019. Those with previous small cell lung cancers or SBRT treatments for tumors other than NSCLC were excluded. Multivariate Cox regression and a matched pair cohort analyses evaluated the prognoses of patients undergoing definitive SBRT for a new second primary.

RESULTS

Of 438 patients who underwent definitive SBRT for NSCLC, 84 had previously treated NSCLC. Univariate log-rank tests identified gender, Karnofksy performance status (KPS), prior lung cancer, anticoagulation use, and history of heart disease to correlate with overall survival (OS) (P<0.05). These factors were incorporated into a multivariate Cox regression model that demonstrated female sex (P=0.004, hazard ratio [HR]=0.68), KPS (P<0.001, HR=2.0), and prior lung cancer (P=0.049, HR=0.7) to be significantly associated with OS. A similar approach found only gender (P=0.017, HR=0.64) and tumor stage (P=0.02, HR=1.7) to correlate with relapse-free survival. To support the Cox regression analysis, propensity score matching was performed using gender, age, KPS, tumor stage, history of heart disease, and anticoagulation use. Kaplan-Meier survival analysis within the matched pairs found prior lung cancer to be associated with improved OS (P=0.011), but not relapse-free survival (P=0.44).

CONCLUSIONS

Compared with initial lung cancer SBRT inoperable cases, ablative radiotherapy for new primaries was associated with improved OS. Physicians should not be dissuaded from offering SBRT to such patients.

A pilot study of stereotactic body radiation therapy (SBRT) after surgery for stage III non-small cell lung cancer

Background

Standard therapy for stage III non-small cell lung cancer with chemotherapy and conventional radiation has suboptimal outcomes. We hypothesized that a combination of surgery followed by stereotactic body radiation therapy (SBRT) would be a safe alternative.

Methods

Patients with stage IIIA (multistation N2) or IIIB non-small cell lung cancer were enrolled from March 2013 to December 2015. The protocol included transcervical extended mediastinal lymphadenectomy (TEMLA) followed by surgical resection, 10 Gy SBRT directed to the involved mediastinum/hilar stations and/or positive surgical margins, and adjuvant systemic therapy. Patients not suitable for anatomic lung resection were treated with 30 Gy to the primary tumor. The primary efficacy end-point was the proportion of patients with grade 3 or higher adverse events (AE) or toxicities.

Results

Of 10 patients, 7 patients underwent neoadjuvant chemotherapy. All patients had TEMLA. Nine of 10 patients underwent surgical resection. The remaining patient had an unresectable tumor and received 30 Gy SBRT to the primary lesion. All patients had post-operative SBRT. Median follow-up was 18 months. There were no perioperative mortalities. Six patients had any grade 3 AEs with no grade 4–5 AEs. Of these, 4 were not attributable to radiation. Pulmonary-related grade 3 AEs were experienced by 2 patients. There were no failures within the 10 Gy volume. Overall survival and progression-free survival rates at 2 years were 68% (90% CI 36–86) and 40% (90% CI 16–63), respectively.

Conclusions

In carefully selected patients with locally advanced non-small cell lung cancer, combining surgery with SBRT was well tolerated with no local failure.

Trial registration

ClinicalTrials.gov identifying number NCT01781741. Registered February 1, 2013.

Stereotactic Body Radiotherapy for the Treatment of Renal Tumors

The purpose of this study was to evaluate the response of actively growing renal masses to stereotactic body radiation therapy (SBRT). We retrospectively reviewed our institutional review board–approved kidney database and identified 4 patients who underwent SBRT, 15 Gy dose, for their rapidly growing renal masses. Three patients had a decreased tumor size after radiation treatment by 20.8%, 38.1%, and 20%. The other patient had a size gain of 5.6%. This patient maintained a similar tumor growth rate before and after SBRT. Mean follow-up time was 13.8 months. SBRT represents an effective management option in select patients with larger rapidly growing kidney masses.

Imaging the mechanics and electromechanics of the heart

The heart is a mechanical pump that is electrically driven. We have previously shown that the contractility of the cardiac muscle can reliably be used in order to assess the extent of ischemia using myocardial elastography. Myocardial elastography estimates displacement and strain during the natural contraction of the myocardium using signal processing techniques on echocardiograms in order to assess the change in mechanical properties as a result of disease. In this paper, we showed that elastographic techniques can be used to estimate and image both the mechanics and electromechanics of normal and pathological hearts in vivo. In order to image the mechanics throughout the entire cardiac cycle, the minimum frame rate was determined to be on the order of 150 fps in a long-axis view and 300 fps in a short-axis view. The incremental and cumulative displacement and strains were measured and imaged for the characterization of normal function and differentiation from infracted myocardium. In order to image the electromechanical function, the incremental displacement was imaged inconsecutive cardiac cycles during end-systole in both dogs and humans. The contraction wave velocity in normal dogs was found to be twice higher than in normal humans and twice lower than in ischemic dogs. In conclusion, we have demonstrated that elastographic techniques can be used to detect and quantify the mechanics and electromechanics of the myocardium in vivo. Ongoing investigations entail assessment of myocardial elastography in characterizing and quantifying ischemia and infarction in vivo.