Fully automated volumetric modulated arc therapy planning for locally advanced rectal cancer: feasibility and efficiency.

BACKGROUND: Volumetric modulated arc therapy (VMAT) for locally advanced rectal cancer (LARC) has emerged as a promising technique, but the planning process can be time-consuming and dependent on planner expertise. We aimed to develop a fully automated VMAT planning program for LARC and evaluate its feasibility and efficiency. METHODS: A total of 26 LARC patients who received VMAT treatment and the computed tomography (CT) scans were included in this study. Clinical target volumes and organs at risk were contoured by radiation oncologists. The automatic planning program, developed within the Raystation treatment planning system, used scripting capabilities and a Python environment to automate the entire planning process. The automated VMAT plan (auto-VMAT) was created by our automated planning program with the 26 CT scans used in the manual VMAT plan (manual-VMAT) and their regions of interests. Dosimetric parameters and time efficiency were compared between the auto-VMAT and the manual-VMAT created by experienced planners. All results were analyzed using the Wilcoxon signed-rank sum test. RESULTS: The auto-VMAT achieved comparable coverage of the target volume while demonstrating improved dose conformity and uniformity compared with the manual-VMAT. V30 and V40 in the small bowel were significantly lower in the auto-VMAT compared with those in the manual-VMAT (p < 0.001 and < 0.001, respectively); the mean dose of the bladder was also significantly reduced in the auto-VMAT (p < 0.001). Furthermore, auto-VMAT plans were consistently generated with less variability in quality. In terms of efficiency, the auto-VMAT markedly reduced the time required for planning and expedited plan approval, with 93% of cases approved within one day. CONCLUSION: We developed a fully automatic feasible VMAT plan creation program for LARC. The auto-VMAT maintained target coverage while providing organs at risk dose reduction. The developed program dramatically reduced the time to approval.

Examination of conversion method of dose distribution of lung cancer IMRT using fluence reversible calculation function in O-ring type linac and C-type linac.

Generally, converting irradiation plans between C-arm linacs (C-linac) when the linac fails is possible without recalculating the dose distribution using a treatment planning system (TPS), because they have similar mechanical structure. However, the O-ring-type linac (O-linac) differs from the C-linac in forming the dose distribution. Therefore, if O-linac breaks down, it is necessary to formulate a treatment plan from scratch. In this study, we investigated a method for converting irradiation from an O-linac to a C-linac. Thirty patients with lung cancer who underwent volumetric-modulated arc therapy with an O-linac were included in this study. The O-linac dose distribution was converted into energy fluence by the function of the TPS. The alternative linac multi-leaf collimator (MLC) was then optimized to achieve energy fluence. The homogeneity index, conformity index, and planning treatment volume (D95%, D2%) of the converted plan were compared with the original plan. For organ at risk (OAR), the dose-volume histograms (DVHs) of the lung, esophagus, heart, and spinal cord were evaluated. Additionally, the shapes of the isodose curves were compared using the Dice similarity coefficient (DSC). There was no significant difference between the target and OARs (p > 0.05). The mean DSCs of 30% to 100% isodose curves of the prescribed dose and the isodose ≥ 105% and ≤ 20%were > 0.8 and < 0.8, respectively. Due to the structural differences of MLC, the dose-volume and generation positions were different in the dose range of ≥ 105% and ≤ 20%; hence, DSCs decreased. However, no statistically significant difference in the DVH was identified for either treatment plan. Based on this result, we propose a simple replanning method for performing MLC fitting after converting the dose to the energy fluence.

Radiation pneumonitis after palliative radiotherapy in cancer patients with interstitial lung disease.

PURPOSE: The risk of radiation pneumonitis (RP) after palliative radiotherapy (RT) in cancer patients with interstitial lung disease (ILD) remains unclear. This study aimed to investigate the incidence, severity, and predictive factors of RP among patients with ILD who received palliative RT. METHODS AND MATERIALS: The medical records of cancer patients with ILD who received palliative RT involving a lung field between January 2008 and December 2019 were retrospectively reviewed. Screening for ILD was performed by using the ICD-10 diagnosis code, and the ILD was evaluated on the basis of pretreatment computed tomography (CT). RP was scored using Common Terminology Criteria for Adverse Events, version 5.0. Associations between both clinical and dosimetric factors and RP were assessed by univariate and multivariate analyses. RESULTS: Sixty-two patients were included in the analysis. The median prescribed physical dose of RT was 25 Gy (range, 6-40 Gy). The RP was graded 1, 2, 3, 4, and 5 in 6 (10%), 3 (5%), 1 (2%), 2 (3%), and 6 (10%) patients, respectively. The median time to onset of grade 3 or more RP (≥Gr3 RP) was 39 days (range, 10-155). The results of the multivariate analysis indicated that ILD pattern was a significant predictive factor for ≥Gr3 RP (odds ratio, 12.0; 95% confidence interval, 1.02-1664; P < 0.05). CONCLUSIONS: RT involving a lung field, even when prescribed with palliative intent, should be administered carefully to ILD patients. Evaluation of the ILD pattern on pretreatment CT images may be of help in determining whether to perform RT.

Comparison of a Hybrid IMRT/VMAT technique with non-coplanar VMAT and non-coplanar IMRT for unresectable olfactory neuroblastoma using the RayStation treatment planning system-EUD, NTCP and planning study.

The purpose of this study was to compare hybrid intensity-modulated radiotherapy (IMRT) and volumetric-modulated arc therapy (Hybrid IMRT/VMAT), with non-coplanar (nc) IMRT and nc-VMAT treatment plans for unresectable olfactory neuroblastoma (ONB). Hybrid IMRT/VMAT, nc-IMRT and nc-VMAT plans were optimized for 12 patients with modified Kadish C stage ONB. Dose prescription was 65 Gy in 26 fractions. Dose-volume histogram parameters, conformation number (CN), homogeneity index (HI), integral dose and monitor units (MUs) delivered per fraction were assessed. Equivalent uniform dose (EUD) and normal tissue complication probability (NTCP) based on the EUD model (NTCPLogit) and the Lyman-Kutcher-Burman model (NTCPLKB) were also evaluated. We found that the Hybrid IMRT/VMAT plan significantly improved the CN for clinical target volume (CTV) and planning treatment volume (PTV) compared with the nc-VMAT plan. In general, sparing of organs at risk (OARs) is similar with the three techniques, although the Hybrid IMRT/VMAT plan resulted in a significantly reduced Dmax to contralateral (C/L) optic nerve compared with the nc-IMRT plan. The Hybrid IMRT/VMAT plan significantly reduce EUD to the ipsilateral (I/L) and C/L optic nerve in comparison with the nc-IMRT plan and nc-VMAT plan, but the difference in NTCP between the three technique was <1%. We concluded that the Hybrid IMRT/VMAT technique can offer improvement in terms of target conformity and EUD for optic nerves, while achieving equal or better OAR sparing compared with nc-IMRT and nc-VMAT, and can be a viable radiation technique for treating unresectable ONB. However, the clinical benefit of these small differences in dosimetric data, EUD and NTCP of optic nerves may be minimal.

Treatment patterns and outcomes change in early-stage non-small cell lung cancer in octogenarians and older: a SEER database analysis.

BACKGROUND: Lung cancer is the most commonly diagnosed cancer and the leading cause of cancer death in the world. AIMS: We used the Surveillance, Epidemiology, and End Results (SEER) database to investigate the changes in the incidence, treatment patterns, and outcomes of early-stage non-small cell lung cancer (NSCLC) in octogenarians and older from 1995 to 2015. METHODS: Using the SEER database, we identified patients ≥ 80 years stage I-IIa NSCLC diagnosed from 1995 to 2015. Changes in the treatment patterns, incidence and proportion, and survival were assessed by years of diagnosis. RESULTS: In total, 25,394 patients were identified. The incidence number sharply increased from 260 in 1995 to 2120 in 2015. There was a tremendous increase in the proportion who underwent radiotherapy from 22.7% in 1995 to 50% in 2015 (P < 0.0001), with a corresponding decrease in surgical treatment, from 50 to 28.6% (P < 0.0001). The 2-year cancer-specific survival (CSS) and overall survival (OS) improved for patients treated with radiation alone and relatively subtly for those who received surgery alone. CONCLUSION: At present, RT has replaced surgery as the most commonly used modality in early-stage NSCLC in patients ≥ 80 years in the United States. An improvement was observed in CSS and OS for patients treated with definitive RT and surgery.

Dose-Volume and Radiobiological Model-Based Comparative Evaluation of the Gastrointestinal Toxicity Risk of Photon and Proton Irradiation Plans in Localized Pancreatic Cancer Without Distant Metastasis.

Background: Radiobiological model-based studies of photon-modulated radiotherapy for pancreatic cancer have reported reduced gastrointestinal (GI) toxicity, although the risk is still high. The purpose of this study was to investigate the potential of 3D-passive scattering proton beam therapy (3D-PSPBT) in limiting GI organ at risk (OAR) toxicity in localized pancreatic cancer based on dosimetric data and the normal tissue complication probability (NTCP) model. Methods: The data of 24 pancreatic cancer patients were retrospectively analyzed, and these patients were planned with intensity-modulated radiotherapy (IMRT), volume-modulated arc therapy (VMAT), and 3D-PSPBT. The tumor was targeted without elective nodal coverage. All generated plans consisted of a 50.4-GyE (Gray equivalent) dose in 28 fractions with equivalent OAR constraints, and they were normalized to cover 50% of the planning treatment volume (PTV) with 100% of the prescription dose. Physical dose distributions were evaluated. GI-OAR toxicity risk for different endpoints was estimated by using published NTCP Lyman-Kutcher-Burman (LKB) models. Analysis of variance (ANOVA) was performed to compare the dosimetric data, and ΔNTCPIMRT-PSPBT and ΔNTCPVMAT-PSPBT were also computed. Results: Similar homogeneity and conformity for the clinical target volume (CTV) and PTV were exhibited by all three planning techniques (P > 0.05). 3D-PSPBT resulted in a significant dose reduction for GI-OARs in both the low-intermediate dose range (below 30 GyE) and the highest dose region (D max and V 50 GyE) in comparison with IMRT and VMAT (P < 0.05). Based on the NTCP evaluation, the NTCP reduction for GI-OARs by 3D-PSPBT was minimal in comparison with IMRT and VMAT. Conclusion: 3D-PSPBT results in minimal NTCP reduction and has less potential to substantially reduce the toxicity risk of upper GI bleeding, ulceration, obstruction, and perforation endpoints compared to IMRT and VMAT. 3D-PSPBT may have the potential to reduce acute dose-limiting toxicity in the form of nausea, vomiting, and diarrhea by reducing the GI-OAR treated volume in the low-to-intermediate dose range. However, this result needs to be further evaluated in future clinical studies.

Radiobiological model-based approach to determine the potential of dose-escalated robust intensity-modulated proton radiotherapy in reducing gastrointestinal toxicity in the treatment of locally advanced unresectable pancreatic cancer of the head.

BACKGROUND: The purpose of this study was to determine the potential of escalated dose radiation (EDR) robust intensity-modulated proton radiotherapy (ro-IMPT) in reducing GI toxicity risk in locally advanced unresectable pancreatic cancer (LAUPC) of the head in term of normal tissue complication probability (NTCP) predictive model. METHODS: For 9 patients, intensity-modulated radiotherapy (IMRT) was compared with ro-IMPT. For all plans, the prescription dose was 59.4GyE (Gray equivalent) in 33 fractions with an equivalent organ at risk (OAR) constraints. Physical dose distribution was evaluated. GI toxicity risk for different endpoints was estimated using published NTCP Lyman Kutcher Burman (LKB) models for stomach, duodenum, small bowel, and combine stomach and duodenum (Stoduo). A Wilcoxon signed-rank test was used for dosimetry parameters and NTCP values comparison. RESULT: The dosimetric results have shown that, with similar target coverage, ro-IMPT achieves a significant dose-volume reduction in the stomach, small bowel, and stoduo in low to high dose range in comparison to IMRT. NTCP evaluation for the endpoint gastric bleeding of stomach (10.55% vs. 13.97%, P = 0.007), duodenum (1.87% vs. 5.02%, P = 0.004), and stoduo (5.67% vs. 7.81%, P = 0.008) suggest reduced toxicity by ro-IMPT compared to IMRT. ∆NTCP IMRT - ro-IMPT (using parameter from Pan et al. for gastric bleed) of ≥5 to < 10% was seen in 3 patients (33%) for stomach and 2 patients (22%) for stoduo. An overall GI toxicity relative risk (NTCPro-IMPT/NTCPIMRT) reduction was noted (0.16-0.81) for all GI-OARs except for duodenum (> 1) with endpoint grade ≥ 3 GI toxicity (using parameters from Holyoake et al.). CONCLUSION: With similar target coverage and better conformity, ro-IMPT has the potential to substantially reduce the risk of GI toxicity compared to IMRT in EDR of LAUPC of the head. This result needs to be further evaluated in future clinical studies.

Stereotactic body radiation therapy for early-stage non-small-cell lung cancer in octogenarians and older: an alternative treatment.

Surgery is the standard modality for early-stage I-II non-small-cell lung cancer (NSCLC). Generally, patients who are >80 years old tend to have more comorbidities and inferior physical status than younger patients. Stereotactic body radiation therapy (SBRT) may provide an alternative treatment for this group of patients. Here, we report our experience using SBRT to in the management of early-stage NSCLC in patients >80 years old. Patients aged ≥80 years old who were diagnosed with early-stage NSCLC and treated with definitive lung SBRT from January 2000 to January 2018 were retrospectively analysed. Local recurrence-free survival (LRFS), regional recurrence-free survival (RRFS), cancer-specific survival (CSS), progression-free survival (PFS), overall survival (OS) and treatment-related toxicities were analysed for patients >80 years old. A total of 153 patients were included, with a median age of 85 years (range, 80-94). The median follow-up period and OS was 39.8 months (range, 10-101 months) and 76 months, respectively. The 3-year OS, PFS, CSS, RRFS and LRFS were 65.3, 58.0, 75.7, 73.9 and 85.3%, respectively. Radiation pneumonitis grade 0-1, grade 2, grade 3 and grade 4 was observed in 135 (88.2%), 13 (8.5%), 4 (2.61%) and 1 (0.6%) patient(s), respectively. On multivariate analyses, tumor size, pretreatment C-reactive protein (CRP) value, histology and pretreatment physical state were significantly associated with OS. Definitive lung SBRT appears to have high LRFS and OS without causing high-grade radiation-related toxicities in early-stage NSCLC patients who were >80 years old.

Prospective evaluation of the setup errors and its impact on safety margin for cervical cancer pelvic conformal radiotherapy.

AIM: The primary objective was to assess set-up errors (SE) and secondary objective was to determine optimal safety margin (SM). BACKGROUND: To evaluate the SE and its impact on the SM utilizing electronic portal imaging (EPI) for pelvic conformal radiotherapy. MATERIAL AND METHODS: 20 cervical cancer patients were enrolled in this prospective study. Supine position with ankle and knee rest was used during CT simulation. The contouring was done using consensus guideline for intact uterus. 50 Gy in 25 fractions were delivered at the isocenter with ≥95% PTV coverage. Two orthogonal (Anterior and Lateral) digitally reconstructed radiograph (DRR) was constructed as a reference image. The pair of orthogonal [Anterior-Posterior and Right Lateral] single exposure EPIs during radiation was taken. The reference DRR and EPIs were compared for shifts, and SE was calculated in the X-axis, Y-axis, and Z-axis directions. RESULTS: 320 images (40 DRRs and 280 EPIs) were assessed. The systematic error in the Z-axis (AP EPI), X-axis (AP EPI), and Y-axis (Lat EPI) ranged from -12.0 to 11.8 mm, -10.3 to 7.5 mm, and -8.50 to 9.70 mm, while the random error ranged from 1.60 to 6.15 mm, 0.59 to 4.93 mm, and 1.02 to -4.35 mm. The SM computed were 7.07, 6.36, and 7.79 mm in the Y-axis, X-axis, and Z-axis by Van Herk's equation, and 6.0, 5.51, and 6.74 mm by Stroom's equation. CONCLUSION: The computed SE helps defining SM, and it may differ between institutions. In our study, the calculated SM was approximately 8 mm in the Z-axis, 7 mm in X and Y axis for pelvic conformal radiotherapy.

Efficacy and safety of accelerated fractionated radiotherapy without elective nodal irradiation for T3N0 glottic cancer without vocal cord fixation.

BACKGROUND: The purpose of this study was to evaluate accelerated fractionated radiotherapy (AFRT) without elective nodal irradiation (ENI) for T3N0 glottic cancer (GC) without vocal cord fixation, especially in comparison with chemoradiotherapy (CRT) and hyperfractionated radiotherapy (HFRT) both of which included ENI. METHODS: The medical charts of patients with T3N0GC without cord fixation received definitive radiotherapy between June 2005 and March 2018 were reviewed. RESULTS: A total of 74 patients were analyzed. After a median follow-up time of 46 months (range, 12-141), 3-year local failure in AFRT/CRT/HFRT (n = 41/10/23) was 10%/20%/26%, 3-year regional failure 6%/0%/9%, 3-year progression-free survival 71%/69%/74%, and 3-year overall survival 77%/100%/87%. There were no significant differences among three groups in recurrence or survival. Grade 3 adverse events (AEs) were noted in 5/2/8 patients (12%/20%/35%) in AFRT/CRT/HFRT, respectively. There were no Grade 4/5 AEs. CONCLUSIONS: AFRT without ENI is an effective and feasible treatment for T3N0GC without cord fixation.

Prospective evaluation of XRCC-1 Arg194Trp polymorphism as bio-predictor for clinical outcome in locally advanced laryngeal cancer undergoing cisplatin-based chemoradiation.

BACKGROUND: To determine X-ray repair cross-complementing 1 gene (XRCC-1) Arg194Trp polymorphism as bio-predictor for clinical outcome in advanced laryngeal squamous cell carcinoma undergoing cisplatin-based chemoradiation (CRT). METHODS: A total of 150 patients were enrolled in this prospective study. XRCC-1 Arg194Trp genotyping categorized patients as wild (C/C) and polymorphic (C/T or T/T). The primary endpoint was to assess acute radiation-induced toxicity (ARIT). RESULTS: A significant correlation of skin (P- .04) and oral mucosal ARIT (P- .01) was noticed in the XRCC-1 polymorphic variant. A higher treatment response was noted in the polymorphic variant, and it shows a trend toward significance (P- .08). With 33 months of median follow-up, 2-year progression-free survival (PFS) and overall survival (OS) of wild vs polymorphic variant were 34.6% vs 46.9% (P- .066) and 50.6% vs 62.2% (P- .12). CONCLUSION: XRCC-1 polymorphic variants have significantly higher grade of >2 ARIT and may have improved trend for treatment response and PFS.

Palliative Radiation Therapy for Macroscopic Hematuria Caused by Urothelial Cancer.

Background: To assess the efficacy and toxicity profiles of palliative radiation therapy (RT) for macroscopic hematuria (MH) caused by urothelial cancer. Methods: A total of 25 urothelial cancer patients with MH who underwent palliative RT between 2008 and 2018 were analyzed in this retrospective study. The hematuria-free survival (HFS) time was defined as the period from complete resolution of MH to the recurrence of MH, death, or the last follow-up examination. Adverse events were classified according to the Common Terminology Criteria for Adverse Events version 4.0. Results: By the end of the median follow-up duration of 90 days (11-886 days), complete resolution of MH had been achieved in 22 patients (88%), and the median interval between the start of RT and resolution of MH was 9 days (2-179 days). Of the 22 patients in whom the symptom resolved, 9 (41%) developed recurrent MH, and the median time to relapse of MH was 129 days (30-692 days). The median RT dose was 30 Gy (20-40 Gy). Nine (36%) patients received a blood transfusion before the RT. The three-month HFS rate was 52.1%. There was a significant difference in the three-month HFS rate between patients with and without a history of pretreatment blood transfusion (HFS rate: 34.6% vs. 61.5%, p = 0.03). Grade 2 urinary tract pain and grade 3 diarrhea were seen in one patient each. Conclusion: Palliative RT appeared to be effective with limited toxicities for urothelial cancer patients with MH.

Impact of Proton Beam Irradiation of an Anatomic Subsegment of the Liver for Hepatocellular Carcinoma.

PURPOSE: The objective of this research was to elucidate the impact on the prognosis, including the survival prognosis, resulting from proton beam irradiation of an anatomic subsegment of the liver (ASPT) for the treatment of hepatocellular carcinoma (HCC). METHODS AND MATERIALS: A total of 110 patients who received a diagnosis of HCC were analyzed in this retrospective study. Definitive proton beam therapy was delivered at a dose of 76 Gy (relative biological effectiveness) in 20 fractions between January 2008 and December 2015. When the HCC widely abutted blood vessels or when multiple HCC tumors occurred within the same liver subsegment, the clinical target volume was outlined as an anatomic subsegment of the liver, according to the portal territory, containing the tumor. In the remaining cases, the clinical target volume was delineated by adding a 5-mm margin around the gross tumor volume. The overall survival (OS), progression-free survival (PFS), and local control rates and adverse events were assessed. A review of the medical charts assessed adverse events that occurred during and after the treatment and were classified according to the Common Terminology Criteria for Adverse Events version 4.0. RESULTS: The median follow-up duration was 36.5 months (range, 1-90.6 months). The median age of the patients was 73 years (range, 48-90 years). ASPT was performed in 31 patients (28%). Three-year OS, PFS, and local control rates were 74.2%, 40.4%, and 91.7%, respectively. Multivariate analysis identified ASPT as a factor that significantly improved PFS (P = .049) but not OS (P = .79). No association was found between ASPT and the frequency of grade ≥3 acute/late adverse events. CONCLUSIONS: ASPT was associated with a reduction in the rate of tumor progression and no significant toxicity but was not associated with OS.

Could excision repair cross-complementing group-1 mRNA expression from peripheral blood lymphocytes predict locoregional failure with cisplatin chemoradiation for locally advanced laryngeal cancer?

AIM: The association of excision repair cross-complementing 1 mRNA (ERCC-1 mRNA) expression with the outcome has been reported with immunohistochemistry (IHC) using tumor tissue in head and neck cancer. We evaluated ERCC-1 mRNA expression by reverse transcription polymerase chain reaction (RT-PCR) from peripheral blood lymphocytes (PBLs) as bio-predictor of locoregional failure (LRF) to chemoradiation (CRT) for locally advanced laryngeal squamous cell cancer (LALSCC). METHODS: A total of 107 male patients with LALSCC were enrolled in this prospective study. ERCC-1 mRNA expression by PBLs was determined by RT-PCR. Definitive CRT was delivered with 35 mg/m2 weekly cisplatin. Response Evaluation Criteria in Solid Tumor 1.1 (RECIST 1.1) were used in evaluating treatment response. The primary objective was to assess LRF. The influence of patient characteristics, treatment response, weekly cisplatin cycles, ERCC mRNA expression was determined for LRF, progression-free survival (PFS) and overall survival (OS). RESULTS: A total of 98 patients completed definitive CRT. The median value of 2-ΔΔCT ERCC-1 mRNA expression was 3.9; based on which it was categorized as low and high. Correlation of ERCC-1 expression with treatment response was insignificant (P- .38). With a median follow-up of 33 months; 2-year LRF, PFS, and OS was 63.3%, 34.7% and 79.4%. The 2-year LRF, PFS and OS for low versus high expression were 53.1% versus 73.5% (P-value = 0.036), 44.9% versus 24.4% (P-value = 0.047) and 81.6% versus 77.2% (P-value = 0.33), respectively. In multivariate analysis, ERCC-1 expression, T-stage, N-stage and tumor subsite are predictive factors for LRF; T-stage and nodal recurrence for OS; stage and treatment response for PFS. CONCLUSION: LALSCC patient with ERCC-1 mRNA low expression was associated with lower LRF rate, and improved PFS.

Hypofractionated proton beam therapy for centrally located lung cancer.

INTRODUCTION: To clarify the efficacy and safety of hypofractionated proton beam therapy (PBT) for centrally located lung cancer. METHODS: We retrospectively reviewed 39 patients who received hypofractionated [≧3 Gy (relative biological effectiveness: RBE)/fraction] PBT for centrally located cT1-2N0M0 (8th edition) lung cancer between 1999 and 2015. A tumour within 2 cm of the proximal bronchial tree was defined as a centrally located tumour. RESULTS: Twenty-four patients (62%) were treated with 80 Gy (RBE) in 20 fractions (112 Gy10 ), whereas eight (21%) were treated with 66 Gy (RBE) in 10 fractions (109.56 Gy10 ). The median follow-up period for censored patients was 48 months (range: 4-140). The 2-year progression-free survival (PFS) and overall survival (OS) rates were 86 and 100% for T1 disease and 56 and 94% for T2 disease, respectively. Patients who received 110 Gy10 or higher showed significantly better PFS than those who received less than 110 Gy10 , while no significant difference was noted in OS between the two groups. The sites of the first progression were local in six patients (27%), regional in seven (32%), distant in seven (32%), and local and distant in two (9%). Among the 13 patients with loco-regional recurrence, only two (15%) received treatments with curative intent. Dyspnoea of grade 3 was noted in one patient (3%), and pneumonitis of grade 2 was noted in four patients (10%). CONCLUSION: Hypofractionated PBT may be a very safe and effective treatment option for centrally located early lung cancer.