Outcomes of accelerated hypofractionated radiotherapy in stage i non-small-cell lung cancer

Toxicity in patients receiving radiotherapy for ultracentral stage I non-small cell lung cancer: A secondary analysis of the LUSTRE randomized trial

BACKGROUND AND PURPOSE

Stereotactic body radiotherapy (SBRT) carries potentially higher risks for ultracentral (UC) NSCLC with limited prospective data to guide decision making. We conducted a secondary analysis from a randomized trial of SBRT and conventionally hypofractionated radiation (CRT) to assess these risks.

MATERIALS AND METHODS

Patients (n = 233) with medically inoperable stage I NSCLC were recruited from 2014 to 2020. Patients with UC targets directly overlapping the proximal bronchial tree (PBT) were identified. The primary objective was the occurrence of related grade 3-5 toxicity > 3 months following radiation. Secondary endpoints included local control, survival, and evaluation of PBT dose and its association with late toxicity.

RESULTS

Thirty UC tumors were identified (23 - SBRT 60 Gy/8 fractions, 7 - CRT 60 Gy/15 fractions). Median age was 72 years, and median tumor size was 2.8 cm. Most patients (67 %) had histologically confirmed NSCLC. At a median follow-up of 2.9 years, 3 and 1 patients developed grade 3 and 5 toxicity respectively (all SBRT). 3-year local control was 85 %. Mean PBT dose (converted to 2 Gy dose equivalents) was higher in patients with grade ≥ 3 toxicity, particularly for 4 cc (105.5 vs 51.8 Gy, p = 0.0004), 5 cc (84 vs 46.1 Gy, p = 0.003), and volumetric doses (V65 - V100Gy). The patient with grade 5 toxicity had the highest 5 cc dose (117 Gy), V90Gy (8.2 cc), and V100Gy (7 cc).

CONCLUSIONS

SBRT for UC NSCLC provides good local control but carries a high rate of late grade 3-5 toxicity. An apparent association between toxicity and PBT volumetric dose was observed, which should be considered if SBRT is offered.

Histology-driven hypofractionated radiation therapy schemes for early-stage lung adenocarcinoma and squamous cell carcinoma

BACKGROUND AND PURPOSE

Histology was found to be an important prognostic factor for local tumor control probability (TCP) after stereotactic body radiotherapy (SBRT) of early-stage non-small-cell lung cancer (NSCLC). A histology-driven SBRT approach has not been explored in routine clinical practice and histology-dependent fractionation schemes remain unknown. Here, we analyzed pooled histologic TCP data as a function of biologically effective dose (BED) to determine histology-driven fractionation schemes for SBRT and hypofractionated radiotherapy of two predominant early-stage NSCLC histologic subtypes adenocarcinoma (ADC) and squamous cell carcinoma (SCC).

MATERIAL AND METHODS

The least-χ2 method was used to fit the collected histologic TCP data of 8510 early-stage NSCLC patients to determine parameters for a well-developed radiobiological model per the Hypofractionated Treatment Effects in the Clinic (HyTEC) initiative.

RESULTS

A fit to the histologic TCP data yielded independent radiobiological parameter sets for radiotherapy of early-stage lung ADC and SCC. TCP increases steeply with BED and reaches an asymptotic maximal plateau, allowing us to determine model-independent optimal fractionation schemes of least doses in 1-30 fractions to achieve maximal tumor control for early-stage lung ADC and SCC, e.g., 30, 44, 48, and 51 Gy for ADC, and 32, 48, 54, and 58 Gy for SCC in 1, 3, 4, and 5 fractions, respectively.

CONCLUSION

We presented the first determination of histology-dependent radiobiological parameters and model-independent histology-driven optimal SBRT and hypofractionated radiation therapy schemes for early-stage lung ADC and SCC. SCC requires substantially higher radiation doses to maximize tumor control than ADC, plausibly attributed to tumor genetic diversity and microenvironment. The determined optimal SBRT schemes agree well with clinical practice for early-stage lung ADC. These proposed optimal fractionation schemes provide first insights for histology-based personalized radiotherapy of two predominant early-stage NSCLC subtypes ADC and SCC, which require further validation with large-scale histologic TCP data.

Optimal Radiation Therapy Fractionation Regimens for Early-Stage Non-Small Cell Lung Cancer

PURPOSE

A series of radiobiological models were developed to study tumor control probability (TCP) for stereotactic body radiation therapy (SBRT) of early-stage non-small cell lung cancer (NSCLC) per the Hypofractionated Treatment Effects in the Clinic (HyTEC) working group. This study was conducted to further validate 3 representative models with the recent clinical TCP data ranging from conventional radiation therapy to SBRT of early-stage NSCLC and to determine systematic optimal fractionation regimens in 1 to 30 fractions for radiation therapy of early-stage NSCLC that were found to be model-independent.

METHODS AND MATERIALS

Recent clinical 1-, 2-, 3-, and 5-year actuarial or Kaplan-Meier TCP data of 9808 patients from 56 published papers were collected for radiation therapy of 2 to 4 Gy per fraction and SBRT of early-stage NSCLC. This data set nearly triples the original HyTEC sample, which was used to further validate the HyTEC model parameters determined from a fit to the clinical TCP data.

RESULTS

TCP data from the expanded data set are well described by the HyTEC models with α/β ratios of about 20 Gy. TCP increases sharply with biologically effective dose and reaches an asymptotic maximal plateau, which allows us to determine optimal fractionation schemes for radiation therapy of early-stage NSCLC.

CONCLUSIONS

The HyTEC radiobiological models with α/β ratios of about 20 Gy determined from the fits to the clinical TCP data for SBRT of early-stage NSCLC describe the recent TCP data well for both radiation therapy of 2 to 4 Gy per fraction and SBRT dose and fractionation schemes of early-stage NSCLC. A steep dose response exists between TCP and biologically effective dose, and TCP reaches an asymptotic maximum. This feature results in model-independent optimal fractionation regimens determined whenever safe for SBRT and hypofractionated radiation therapy of early-stage NSCLC in 1 to 30 fractions to achieve asymptotic maximal tumor control, and T2 tumors require slightly higher optimal doses than T1 tumors. The proposed optimal fractionation schemes are consistent with clinical practice for SBRT of early-stage NSCLC.

Accelerated hypofractionated radiotherapy with 3 Gy per fraction for central/ultra-central lung tumors: toxicity to mediastinal organs

BACKGROUND

Accelerated hypofractionated radiotherapy with 3 Gy per fraction is routinely performed for central lung tumors in Japan. However, the tolerable doses to mediastinal organs at risk during this procedure are unclear. This study aimed to clarify the rate of toxicities and tolerable doses to mediastinal organs.

METHODS

Patients treated with accelerated hypofractionated radiotherapy using a total dose of 60-75 Gy, with 3 Gy per fraction, for central lung tumors (July 2009-April 2021) were retrospectively reviewed. We extracted patients who received ≥30 Gy irradiation to each mediastinal organ and analyzed dosimetric factors, including doses to 0.03, 0.5, 1, 4 and 10 mL of each organ, in relation to grade 3-5 toxicities, except for radiation pneumonitis.

RESULTS

In total, 251 organs in 91 (ultra-central, 24) lesions were analyzed, with a median follow-up duration of 26 months (range, 4-94). The prescribed doses were 75/72/69/66/63/60 Gy for 52/14/16/3/2/4 lesions, respectively. Grade 3 bronchopulmonary hemorrhage was confirmed in two (2.2%) patients, whose tumors were located ultra-centrally. The two patients with toxicity received up to 74.5 and 71.6 Gy to the bronchus. Among patients who received 70 Gy or more to the bronchus, the incidence rate was 7% (2/28 patients).

CONCLUSION

The rate of severe toxicities was low (2.2%). Although we did not identify the dose tolerance of the organs, because of the low incidence rate, we did note that doses of >70 Gy to the bronchus were likely to cause bronchopulmonary hemorrhage.

Hypofractionated Volumetric-Modulated Arc Radiotherapy for Patients With Non-Small-Cell Lung Cancer Not Suitable for Surgery or Conventional Chemoradiotherapy or SBRT

Background

Hypofractionated radiotherapy (HypoRT) has been used to pursue an alternative treatment regimen for patients with non-small-cell lung cancer (NSCLC) who are not eligible for stereotactic ablative radiotherapy (SABR), surgery or concurrent chemoradiotherapy (CCRT) and has shown good local control and safety. We analyzed the feasibility of using volumetric-modulated arc radiotherapy (VMAT) with the simultaneous integrated boost (SIB) technique to achieve high local control with few treatment-related toxicities.

Patients and Methods

A total of 55 patients with stage I-IV NSCLC who were not candidates for SABR, surgery or CCRT were included in the present study. All patients received a prescribed dose of 60 to 66 Gy in 15 fractions. Local progression-free survival (LPFS), PFS, overall survival (OS), and toxicities were retrospectively analyzed.

Results

Thirty-three patients (60.0%) had stage IV or recurrent disease in this study. The median follow-up time was 8 months (interquartile range: 5.0-16.3 months). The 1-year and 2-year OS rates were 84.3% and 69.9%, and the 1-year and 2-year LPFS rates were 91.0% and 63.0%. The median OS (mOS) and median LPFS (mLPFS) were not reached, and median PFS (mPFS) was 15 months. Twenty-eight (51.9%) patients had disease progression at the time of analysis. Of these, 7 (13.0%), 7 (13.0%) and 21 (38.9%) had local recurrence, locoregional failure and distant metastasis, respectively. All cases of local recurrence were found within the SIB region. Four patients had grade 2-3 pneumonitis, and 8 patients had grade 2-3 esophagitis. Patients with grade 2-3 esophagitis had significantly higher maximum dose and dose to 5 cm³ volume to esophagus than those with grade 0-1 esophagitis. No grade 4 or higher toxicity was observed.

Conclusion

The 60 to 66 Gy in 15 fractions RT regimen provides favorable local control and survival with well-tolerated toxicities. Hypofractionated VMAT+SIB is an alternative treatment option for patients with NSCLC who cannot tolerate standard definitive therapy.

Local Control After Stereotactic Body Radiation Therapy for Stage I Non-Small Cell Lung Cancer

PURPOSE

Numerous dose and fractionation schedules have been used to treat medically inoperable stage I non-small cell lung cancer (NSCLC) with stereotactic body radiation therapy (SBRT) or stereotactic ablative radiation therapy. We evaluated published experiences with SBRT to determine local control (LC) rates as a function of SBRT dose.

METHODS AND MATERIALS

One hundred sixty published articles reporting LC rates after SBRT for stage I NSCLC were identified. Quality of the series was assessed by evaluating the number of patients in the study, homogeneity of the dose regimen, length of follow-up time, and reporting of LC. Clinical data including 1, 2, 3, and 5-year tumor control probabilities for stages T1, T2, and combined T1 and T2 as a function of the biological effective dose were fitted to the linear quadratic, universal survival curve, and regrowth models.

RESULTS

Forty-six studies met inclusion criteria. As measured by the goodness of fit χ2/ndf, with ndf as the number of degrees of freedom, none of the models were ideal fits for the data. Of the 3 models, the regrowth model provides the best fit to the clinical data. For the regrowth model, the fitting yielded an α-to-β ratio of approximately 25 Gy for T1 tumors, 19 Gy for T2 tumors, and 21 Gy for T1 and T2 combined. To achieve the maximal LC rate, the predicted physical dose schemes when prescribed at the periphery of the planning target volume are 43 ± 1 Gy in 3 fractions, 47 ± 1 Gy in 4 fractions, and 50 ± 1 Gy in 5 fractions for combined T1 and T2 tumors.

CONCLUSIONS

Early-stage NSCLC is radioresponsive when treated with SBRT or stereotactic ablative radiation therapy. A steep dose-response relationship exists with high rates of durable LC when physical doses of 43-50 Gy are delivered in 3 to 5 fractions.

Hypofractionation in Early Stage Non-Small Cell Lung Cancer

Radiation treatment of early stage nonsmall cell lung cancer has evolved over the past 2 decades to progressively more hypofractionated treatment courses. Results comparable to surgical resection are seen with stereotactic body radiotherapy, which is now the standard of care for medically inoperable patients, and a treatment option for operable patients as well. Understanding of the optimal radiation dose and fractionation are evolving, especially for central tumors which have higher treatment toxicity than peripheral tumors.

Accelerated Hypofractionated Radiotherapy Versus Stereotactic Body Radiotherapy for the Treatment of Stage I Nonsmall Cell Lung Cancer-A Single Institution Experience With Long-Term Follow-Up

Purpose:

Although stereotactic body radiation therapy is one of the standard treatments for stage I nonsmall cell lung cancer, in the case of central tumors it carries the risk of severe adverse events for serial organs. Accelerated hypofractionated radiotherapy is considered a reasonable alternative to treat central tumors. We have been treating central tumors with accelerated hypofractionated radiotherapy using a 75 Gy/25 fr/5 weeks regimen, and we compared the results with those of stereotactic body radiation therapy using 48 Gy/4 fr/1 week.

Methods:

Patients with central tumors and/or unfit for 1-hour fixation were candidates for accelerated hypofractionated radiotherapy. Based on the proximity to the biologically effective dose at 10 Gy, above accelerated hypofractionated radiotherapy regimen was adopted.

Results:

From October 2003 to December 2010, 159 patients, who received either accelerated hypofractionated radiotherapy (103 cases) or stereotactic body radiation therapy (56 cases), were included in the analysis. In the accelerated hypofractionated radiotherapy group, 40 (39%) cases were central tumors, whereas all cases were peripheral tumors in the stereotactic body radiation therapy group. Overall 5-year local control and survival rates were 81.9% (95% confidence interval 73.6%-90.1%) and 46.5% (95% confidence interval 36.7%-56.2%), respectively for the accelerated hypofractionated radiotherapy group, and 75.4% (95% confidence interval 63.0%-87.8%) and 44.6% (95% confidence interval 31.6%-57.7%), respectively for the stereotactic body radiation therapy group (n.s.). Among central tumors, ultracentral tumors (21 cases) and the remaining central tumors (19 cases) were similar in both local control and survival. On multivariate analysis, hazard ratios for accelerated hypofractionated radiotherapy versus stereotactic body radiation therapy were <1 for both local control and survival. Pulmonary toxicity was similar in both groups. No serial organ toxicity was observed for central tumors.

Conclusions:

Accelerated hypofractionated radiotherapy with a 75 Gy/25 fr/5 weeks regimen is promising in that it can obtain similar local control and survival results to stereotactic body radiation therapy, and it can control both central and peripheral tumors without any serial organ toxicities. Based on these results, prospective multicenter trials are worth conducting, especially for ultracentral tumors.

Inoperable early-stage primary and early recurrent non-small cell lung cancer: outcomes of a mono-institutional experience using a moderate hypofractionated schedule

BACKGROUND

Patients with medically inoperable early-stage non-small cell lung cancer (NSCLC) may beneficiate of a hypofractionated radiation therapy in order to intensificate the treatment and to reduce the number of hospital access.

METHODS

From 2007 to 2015, 27 patients with early-stage primary or limited loco-regional recurrent (T2a > 4 cm, T2b N0 or T1-2 N1M0) NSCLC were treated. All patients were medically inoperable or refused surgery and were treated with 60 Gy in 20 fractions, 5 times per week. Thirteen (48.1%) presented limited recurrence after surgery and 14 (51.9%) primary disease.

RESULTS

Median follow-up was 34 months. Twelve patients achieved a CR (44.4%) and 8 a PR (29.6%) with a tumour response rate of 74%. Median overall survival (OS) and 2-year OS were 34 months and 63.0%, respectively. Median and 2-year loco-regional progression-free survival (LR-PFS) were 31 months and 51.4%, respectively. Survival outcomes were statistically favourable in patients with partial or complete response with respect to patients with stable or progressive disease, whereas stage (N0 vs N1) and primary or relapse/recurrent disease not. No cases of acute toxicity > grade 2 were observed. Seven patients (25.9%) presented grade 2 late toxicities.

CONCLUSION

Sixty Gy in 20 fractions is well tolerated and achieves good clinical outcomes in early primary or recurrent NSCLC patients. A greater number of patients and a longer follow-up are necessary to confirm the results obtained with our treatment.

Relationship between Contrast-Enhanced CT and Clinicopathological Characteristics and Prognosis of Non-Small Cell Lung Cancer

BACKGROUND

This study investigated the relationship between contrast-enhanced computed tomography (CECT) and clinicopathological characteristics and prognosis of non-small cell lung cancer (NSCLC).

METHODS

A total of 198 NSCLC patients admitted to Enze Hospital from February 2009 to July 2012 underwent pre-surgical CECT to investigate parameters such as tumor size, CECT enhancement, lymph node enlargement, and lymph node size. Chi-square and log-rank tests were used to analyze associations between CECT parameters and pathological features as well as correlations of CECT parameters with prognosis. A Cox proportional hazard model and logistic regression analysis were applied to identify independent risk factors for prognosis.

RESULTS

Tumor size, CECT enhancement, and lymph node enlargement and size were related to degree of differentiation, TNM stage, and lymph node metastasis. Tumor size, lymph node enlargement and metastasis, lymph node size, and CECT enhancement were independent risk factors for NSCLC prognosis. Large tumors and lymph nodes, tumor enhancement, and enlarged and metastatic lymph nodes indicated a poor prognosis.

CONCLUSION

Our study indicates that CECT features can be associated with clinicopathological characteristics and can predict the prognosis of patients with NSCLC.

Tumor control probability modeling for stereotactic body radiation therapy of early-stage lung cancer using multiple bio-physical models

This work is to analyze pooled clinical data using different radiobiological models and to understand the relationship between biologically effective dose (BED) and tumor control probability (TCP) for stereotactic body radiotherapy (SBRT) of early-stage non-small cell lung cancer (NSCLC). The clinical data of 1-, 2-, 3-, and 5-year actuarial or Kaplan-Meier TCP from 46 selected studies were collected for SBRT of NSCLC in the literature. The TCP data were separated for Stage T1 and T2 tumors if possible, otherwise collected for combined stages. BED was calculated at isocenters using six radiobiological models. For each model, the independent model parameters were determined from a fit to the TCP data using the least chi-square (χ²) method with either one set of parameters regardless of tumor stages or two sets for T1 and T2 tumors separately. The fits to the clinic data yield consistent results of large α/β ratios of about 20Gy for all models investigated. The regrowth model that accounts for the tumor repopulation and heterogeneity leads to a better fit to the data, compared to other 5 models where the fits were indistinguishable between the models. The models based on the fitting parameters predict that the T2 tumors require about additional 1Gy physical dose at isocenters per fraction (⩽5 fractions) to achieve the optimal TCP when compared to the T1 tumors. In conclusion, this systematic analysis of a large set of published clinical data using different radiobiological models shows that local TCP for SBRT of early-stage NSCLC has strong dependence on BED with large α/β ratios of about 20Gy. The six models predict that a BED (calculated with α/β of 20) of 90Gy is sufficient to achieve TCP⩾95%. Among the models considered, the regrowth model leads to a better fit to the clinical data.

Normal tissue considerations and dose-volume constraints in the moderately hypofractionated treatment of non-small cell lung cancer

Hypofractionated radiation therapy (RT) regimes in non-small cell lung cancer (NSCLC) have become increasingly popular with a number of international trials currently underway. The majority of the dose-volume-constraints (DVCs) published in the literature refer to conventional 2Gy per fraction deliveries. Here relevant organs-at-risk (OARs) are identified and available dose-volume constraint data discussed and summarised for moderately hypofractionated NSCLC regimes. The OARs examined include lung, brachial plexus, heart, oesophagus, airway and spinal cord. Where available the toxicity rates are also reported with all data summarised tabulated to aid its use in the clinic.

Outcomes of Modestly Hypofractionated Radiation for Lung Tumors: Pre- and Mid-Treatment Positron Emission Tomography-Computed Tomography Metrics as Prognostic Factors

Many patients with lung tumors have tumors too large for stereotactic ablative radiotherapy and comorbidities precluding concurrent chemotherapy. We report the outcomes of 29 patients treated with hypofractionated radiotherapy (RT) to 60 to 66 Gy in 3-Gy fractions. We also report an exploratory analysis of the prognostic value of the pre- and mid-RT positron emission tomography-computed tomography.

INTRODUCTION

Modestly hypofractionated radiation therapy (HypoRT; 60-66 Gy in 3-Gy fractions) allows patients with locally advanced thoracic tumors and poor performance status to complete treatment within a shorter period without concurrent chemotherapy. We evaluated the outcomes and imaging prognostic factors of HypoRT.

MATERIALS AND METHODS

We retrospectively reviewed the data from all patients with primary and metastatic intrathoracic tumors treated with HypoRT from 2006 to 2012. We analyzed the survival and toxicity outcomes, including overall survival (OS), progression-free survival (PFS), local recurrence (LR), and distant metastasis. We also evaluated the following tumor metrics in an exploratory analysis: gross tumor volume (GTV), maximum standardized uptake value (SUVMax), and metabolic tumor volume using a threshold of ≥ 50% of the SUVMax (MTV50%) or the maximum gradient of fluorine-18 fluorodeoxyglucose uptake (MTVEdge). We assessed the association of these metrics and their changes from before to mid-RT using positron emission tomography-computed tomography (PET-CT) with OS and PFS.

RESULTS

We identified 29 patients, all with pre-RT and 20 with mid-RT PET-CT scans. The median follow-up period was 15 months. The 2-year overall and non-small-cell lung cancer-only rate for OS, PFS, and LR, was 59% and 59%, 52% and 41%, and 27% and 32%, respectively. No grade ≥ 3 toxicities developed. The median decrease in GTV, SUVMax, and MTVEdge was 11%, 24%, and 18%, respectively. Inferior OS was associated with a larger pre-RT MTVEdge (P = .005) and pre-RT MTV50% (P = .007). Inferior PFS was associated with a larger mid-RT SUVMax (P = .003).

CONCLUSION

These findings add to the growing body of data demonstrating promising outcomes and limited toxicity with HypoRT. The pre- and mid-RT PET-CT metrics could be useful for prognostic stratification in future clinical trials.

Comparison of accelerated hypofractionation and stereotactic body radiotherapy for Stage 1 and node negative Stage 2 non-small cell lung cancer (NSCLC)

PURPOSE

Stereotactic body radiation therapy (SBRT) and accelerated hypofractionated radiation therapy (AHRT) have favorable local control (LC) relative to conventional fractionation in the treatment of stage I non-small cell lung cancer (NSCLC). We report the results of our single institution experience with the treatment of early stage NSCLC with SBRT or AHRT in cases where SBRT was felt to be suboptimal.

METHODS

One hundred and sixty patients with Stage 1 and node negative Stage 2 NSCLC were treated with SBRT or AHRT from 2003 to 2011. Median follow-up was 29.4 and 19 months (mo), respectively. The median dose was 54Gy in 3 fractions (fx) (SBRT) and 70.2Gy in 26 fx (AHRT). Acute and late toxicities (tox) were graded (G) per CTCAE v4. Time to local (LF), regional (RF) and distant (DF) failure were estimated using the Kaplan-Meier method. The impact of patient and tumor related factors on LF were estimated by multivariate Cox proportional hazard model.

RESULTS

Three-year LC rates were 87.7% (SBRT) and 71.7% (AHRT). The 3-year freedom from DF was 73.3% and 68.1%. Median OS was 38.4 (95% CI 29.7-51.6) and 35 (95% CI 22-48.3) mo. No G3 or 4 tox were observed. At 1 year, 30% and 50% of complications resolved, while (5-6%) had persistent chest wall pain. Multivariate analysis demonstrated that increasing dose per fraction and tumor size (>5.5 vs. 4cm) in the AHRT and SBRT group were found to be associated with a reduced (HR 0.33 95% CI 0.13-0.84, p=0.021) and increased (HR: 6.372 95% CI 1.23-32.92, p=0.027) hazard for local failure respectively.

CONCLUSIONS

Our results compare favorably with other reports of treatment for early stage NSCLC. AHRT patients had comparable LC despite increased size and central disease. Toxicity was limited and overall survival, regional and distant recurrences were similar between groups.

Cost-Effectiveness Analysis Comparing Conventional Versus Stereotactic Body Radiotherapy for Surgically Ineligible Stage I Non–Small-Cell Lung Cancer

The authors show that based on a threshold of $50,000 per life-year gained, stereotactic body radiotherapy seems cost effective compared with conventionally fractionated radiotherapy.

Alternatives to surgery in early stage disease-stereotactic body radiotherapy

The management of early stage non-small cell lung carcinoma (NSCLC) has been revolutionized by the introduction of stereotactic body radiotherapy (SBRT). SBRT is now the standard of care for medically inoperable patients with early stage NSCLC. However, the role of SBRT in medically operable patients remains controversial. This article will review the indications, the technical considerations, image guidance principles, potential toxicities and special circumstances in lung SBRT.