A study on the dosimetric accuracy of treatment planning for stereotactic body radiation therapy of lung cancer using average and maximum intensity projection images

Purpose

To assess the accuracy of current stereotactic body radiation therapy (SBRT) lung treatment planning methodologies on irregular breathing patterns, we have performed a systematic dosimetric evaluation in phantoms by utilizing maximum intensity projection (MIP) and average (AVG) images generated from four dimensional computed tomography (4DCT).

Methods

A custom built programmable lung phantom was used to simulate tumor motions due to various breathing patterns of patients. 4DCT scans were obtained in helical mode, and reconstructed AVG and MIP datasets were imported into the Pinnacle 8.0 h treatment planning system. SBRT plans were generated and executed, and delivered doses were measured by radiochromic film for analysis.

Results

For targets moving regularly or irregularly within a small range (7.0 ± 1.8 mm, n = 6), we observed good agreement between the measured and computed dose distributions. However, for targets moving irregularly with a larger range (20.8 ± 2.6 mm, n = 4), the measured isodose lines were found to be shifted relative to the planned distribution, resulting in an under-dosing (over 10%) in a portion of the PTV. We further observed that the discrepancy between planned and measured dose distribution is due to the inaccurate representation of irregular target motion in the MIP images generated from 4DCT.

Conclusions

Caution should be used when planning from 4DCT images in the presence of large and irregular target motion. The inaccuracy inherent in 4DCT MIP and AVG images can be mitigated through the application of methodologies to reduce respiratory motion, such as abdominal compression, and through the use of volumetric image guidance (e.g., cone beam CT - CBCT) to assure precise targeting with minimal shifts.     

Potential of image-guidance, gating and real-time tracking to improve accuracy in pulmonary stereotactic body radiotherapy

Purpose

To evaluate the potential of image-guidance, gating and real-time tumor tracking to improve accuracy in pulmonary stereotactic body radiotherapy (SBRT).

Materials and methods

Safety margins for compensation of inter- and intra-fractional uncertainties of the target position were calculated based on SBRT treatments of 43 patients with pre- and post-treatment cone-beam CT imaging. Safety margins for compensation of breathing motion were evaluated for 17 pulmonary tumors using respiratory correlated CT, model-based segmentation of 4D-CT images and voxel-based dose accumulation; the target in the mid-ventilation position was the reference.

Results

Because of large inter-fractional base-line shifts of the tumor, stereotactic patient positioning and image-guidance based on the bony anatomy required safety margins of 12 mm and 9 mm, respectively. Four-dimensional image-guidance targeting the tumor itself and intra-fractional tumor tracking reduced margins to <5 mm and <3 mm, respectively. Additional safety margins are required to compensate for breathing motion. A quadratic relationship between tumor motion and margins for motion compensation was observed: safety margins of 2.4 mm and 6 mm were calculated for compensation of 10 mm and 20 mm motion amplitudes in cranio-caudal direction, respectively.

Conclusion

Four-dimensional image-guidance with pre-treatment verification of the target position and online correction of errors reduced safety margins most effectively in pulmonary SBRT.     

Use of megavoltage cine-images for studying intra-thoracic motion during radiotherapy for locally advanced lung cancer

Background and purpose

Use of planning 4-dimensional CT (4DCT) scans often permits use of smaller target volumes for thoracic tumors but this assumes a reproducible pattern of motion during radiotherapy. We compared cranio-caudal (CC) motion on MV cine-images acquired during treatment with that seen on planning 4DCT.

Methods and materials

A pre-programmable respiratory motion phantom and a software tool for motion assessment were used to validate the use of MV cine-images for motion detection. MV cine-images acquired in 20 patients with node-positive lung cancer were analyzed using the same software. Intra-fraction CC motion on 6 MV cine-images from each patient was compared with CC motion on their planning 4DCT.

Results

Software-based motion measurement on MV cine-images from the phantom corresponded to actual motion. Mean CC motion of primary tumor, carina and hilus on 4DCT was 7.3 mm (range 2-13.8 mm), 6.8 mm (1.8-21.2) and 11.0 mm (4.2-15.1), respectively. Corresponding intra-fraction motion on MV cine was 4.1 mm (0.6-13.6 mm); 2.7 mm (0-10 mm) and 6.0 mm (1.8-14.4 mm), respectively. The tumor, hilus and carina could be tracked in 95%, 88% and 38% of the MV cine-images, respectively.

Conclusions

Intra-fraction motion can be reliably measured using MV-cine images from a phantom. Motion discrepancies identified on MV cine-images can identify patients in whom planning 4DCT scans are not representative.     

A comparison of two immobilization systems for stereotactic body radiation therapy of lung tumors

Purpose

This study aims to compare the efficacy, efficiency and comfort level of two immobilization systems commonly used in lung stereotactic body radiation therapy (SBRT): the Bodyfix and the abdominal compression plate (ACP).

Materials and methods

Twenty-four patients undergoing SBRT for medically inoperable stage I lung cancer or pulmonary metastases were entered on this prospective randomized study. All underwent 4DCT simulation with free breathing, the Bodyfix, and the ACP to assess respiratory tumor motion. After CT simulation, patients were randomly assigned to immobilization with either the Bodyfix or the ACP for the actual SBRT treatment. Cone beam CTs (CBCTs) were acquired before and after each treatment to assess intrafraction tumor motion. Setup time and patient comfort were recorded.

Results

There were 16 upper lobe, two middle lobe and seven lower-lobe lesions. Both the Bodyfix and the ACP significantly reduced the superior-inferior (SI) and overall respiratory tumor motion compared to free breathing (4.6 and 4.0 vs 5.3 mm; 5.3 and 4.7 vs 6.1 mm, respectively, p < 0.05). The ACP further reduced the SI and overall respiratory tumor motion compared to the Bodyfix (p < 0.05). The mean overall intrafraction tumor motion was 2.3 mm with the Bodyfix and 2.0 mm with the ACP (p > 0.05). The ACP was faster to set up and rated more comfortable by patients than the Bodyfix (p < 0.05).

Conclusions

While there is no significant difference between the Bodyfix and ACP in reducing intrafraction tumor motion, the ACP is more comfortable, faster to set up, and superior to the Bodyfix in reducing SI and overall respiratory tumor motion.     

A novel simple approach for incorporation of respiratory motion in stereotactic treatments of lung tumors

Purpose

An internal target volume (ITV) is often used for incorporating tumor motion into radiotherapy planning but it overestimates the margins necessary for breathing motion. We describe a pragmatic approach using maximum- and minimum-intensity projections (MIP and Min-IP) only, for reducing ITVs in stereotactic radiotherapy by using dosimetric margins that compensate for motion-induced dose blurring.

Patients and method

We studied tumor motion characteristics from 26 repeat 4DCT scans derived from 10 patients. These were used to calculate the shift in cranio-caudal direction of the 80% isodose due to dose blurring of the time-averaged dose distribution caused by respiratory motion. The dosimetric margins necessary to compensate for dose blurring were calculated relative to the ITV, which can be determined efficiently using the MIP. Peak-to-peak motion amplitude was determined using the MIP and Min-IP. A programmable respiratory motion phantom was used to investigate imaging artifacts in determining the ITV for realistic motion patterns. Dose profiles were both calculated and measured in lung- and water-equivalent tissue.

Results

Using margins for the 80% dose level permitted the use of smaller target volumes relative to the use of ITV-based volumes, with (i) greater reductions seen at the end-inspiration edge than at expiration side due to asymmetric breathing motion patterns and (ii) a linear relationship seen with breathing amplitude. The average reduction of the ITV at a 95% confidence level is given by 0.2 × A_pp − 1.3 mm at expiration side, where A_pp is the peak-to-peak breathing amplitude, and 0.3 × A_pp − 2.2 mm at inspiration side. Dosimetric margins did not differ significantly between water-equivalent and lung tissue for 80% isodose.

Conclusion

A simple margin recipe for breathing motion linear with breathing amplitude can be used to calculate the ITV reductions achievable for stereotactic radiotherapy of lung tumors.     

Effects of genistein following fractionated lung irradiation in mice

Background and purpose

This study investigated protection of lung injury by genistein following fractionated doses of radiation and its effect on tumor response.

Material and methods

C3H/HeJ mice were irradiated (100 kVp X-rays) with 9 fractions of 3.1 Gy over 30 days (approximately equivalent to 10 Gy single dose) and were maintained on a genistein diet (∼10 mg/kg). Damage was assessed over 28 weeks in lung cells by a cytokinesis block micronucleus (MN) assay and by changes in breathing rate and histology. Tumor protection was assessed using a colony assay to determine cell survival following in situ irradiation of small lung nodules (KHT fibrosarcoma).

Results

Genistein caused about a 50% reduction in the MN damage observed during the fractionated radiation treatment and this damage continued to decrease at later times to background levels by 16 weeks. In mice not receiving Genistein MN levels remained well above background out to 28 weeks after irradiation. Genistein reduced macrophage accumulation by 22% and reduced collagen deposition by 28%. There was minimal protection against increases in breathing rate or severe morbidity during pneumonitis. No tumor protection by genistein treatment was observed.

Conclusions

Genistein at the dose levels used in this study partially reduced the extent of fibrosis developing in mouse lung caused by irradiation but gave minimal protection against pneumonitis. There was no evidence that genistein caused protection of small tumors growing in the lung.     

The accuracy of frameless stereotactic intracranial radiosurgery

Purpose

To determine the accuracy of frameless stereotactic radiosurgery using the BrainLAB ExacTrac system and robotic couch by measuring the individual contributions such as the accuracy of the imaging and couch correction system, the linkage between this system and the linac isocenter and the possible intrafraction motion of the patient in the frameless mask.

Materials and methods

An Alderson head phantom with hidden marker was randomly positioned 31 times. Automated 6D couch shifts were performed according to ExacTrac and the deviation with respect to the linac isocenter was measured using the hidden marker. ExacTrac-based set-up was performed for 46 patients undergoing hypofractionated stereotactic radiotherapy for 135 fractions, followed by verification X-rays. Forty-three of these patients received post-treatment X-ray verification for 79 fractions to determine the intrafraction motion.

Results

The hidden target test revealed a systematic error of 1.5 mm in one direction, which was corrected after replacement of the system calibration phantom. The accuracy of the ExacTrac positioning is approximately 0.3 mm in each direction, 1 standard deviation. The intrafraction motion was 0.35 ± 0.21 mm, maximum 1.15 mm.

Conclusion

Intrafraction motion in the BrainLAB frameless mask is very small. Users are strongly advised to perform an independent verification of the ExacTrac isocenter in order to avoid systematic deviations.     

Comparative study of respiratory motion correction techniques in cone-beam computed tomography

Background and purpose

To validate the clinical usefulness of motion-compensated (MC) cone-beam (CB) computed tomography (CT) for image-guided radiotherapy (IGRT) in comparison to four-dimensional (4D) CBCT and three-dimensional (3D) CBCT.

Material and methods

Forty-eight stereotactic body radiation therapy (SBRT) patients were selected. Each patient had 5-12 long CB acquisitions (4 min) and 1-7 short CB acquisitions (1 min), with a total of 349 and 150 acquisitions, respectively. 3D, 4D and MC CBCT images of every acquisition were reconstructed. Image quality, tumor positioning accuracy and tumor motion amplitude were quantified.

Results

The mean image quality of long short acquisitions, measured using the correlation ratio with the planning CT, was 74%/70%, 67%/47% and 79%/74% for 3D, 4D and MC CBCT, respectively; both 4D and MC CBCT were corrected for respiratory motion artifacts but 4D CBCTs suffered from streak artifacts. Tumor positioning with MC CBCT was significantly closer to 4D CBCT than 3D CBCT (p < 0.0001). Detailed patient analysis showed that motion correction was not required for tumors with less than 1 cm motion amplitude.

Conclusions

4D and MC CBCT both allow accurate tumor position analysis under respiratory motion but 4D CBCT requires longer acquisition time than MC CBCT for adequate image quality. MC CBCT can therefore advantageously replace 4D CBCT in clinical protocols for patients with large motion to improve image quality and reduce acquisition time.     

Prognostic effect of stromal lymphocyte infiltration in thymic carcinoma

Background

The purpose of this study was to clarify the relationship between the tumor infiltrating lymphocytes and clinical outcome in patients with thymic carcinoma.

Methods

Tissue specimens from 32 patients who underwent surgical resection for thymic carcinoma were immunohistochemically analyzed for CD4, CD8 and CD20 expression.

Results

Tumor-infiltrating lymphocytes were generally more abundant in the stroma. The patients with low CD4+ lymphocytes (p = 0.037) and low CD20+ lymphocytes (p = 0.045) within tumor stroma showed poor survival. Furthermore, concurrent low levels of CD4+ and CD20+ (p = 0.014), CD8+ and CD20+ (p = 0.025), and, CD4+, CD8+, and CD20+ (p = 0.025) in tumor stroma were significantly associated with poor prognosis when compared to the others group.

Conclusion

Our results indicate that infiltrating CD4+, CD8+, and CD20+ lymphocytes in cancer stroma may cooperate to suppress cancer progression and their presence together appear to be prognostic factor in thymic carcinoma.     

Stereotactic radiotherapy with real-time tumor tracking for non-small cell lung cancer: Clinical outcome

Purpose

To report the clinical outcome of treatment using real-time tumor tracking for 70 patients with inoperable stage I non-small cell lung cancer (NSCLC).

Materials and methods

Seventy inoperable patients with peripherally located early-stage NSCLC were treated with 45 or 60 Gy in three fractions using CyberKnife. Pathology was available in 51% of patients. Thirty-nine patients had a T1-tumor and 31 had a T2-tumor. Markers were placed using the vascular, percutaneous intra-, or extra-pulmonary approach, depending on the risk of pneumothorax.

Results

The actuarial 2-year local control rate for patients treated with 60 Gy was 96%, compared to 78% for patients treated with a total dose of 45 Gy (p = 0.197). All local recurrences (n = 4) occurred in patients with T2-tumors. Overall survival for the whole group at two years was 62% and the cause specific survival was 85%. The median follow-up was 15 months. Grade 3 toxicity occurred in two patients (3%) after marker placement. Treatment-related late grade 3 toxicity occurred in 7 patients (10%). No grade ?4 toxicity occurred.

Conclusion

Excellent local control of 96% at 1- and 2-years was achieved using 60 Gy in three fractions for NSCLC patients treated with the real-time tumor tracking. Toxicity was low.     

MR-guided simultaneous integrated boost in preoperative radiotherapy of locally advanced rectal cancer following neoadjuvant chemotherapy

Purpose

To evaluate a simultaneous integrated boost (SIB) strategy in preoperative radiotherapy of rectal cancer patients following neoadjuvant chemotherapy using pre- and post-chemotherapy tumor volumes assessed by MRI.

Materials and methods

Ten patients with locally advanced rectal cancer, receiving chemotherapy prior to radiotherapy, were included in this study. Pre- and post-chemotherapy MR tumor images were co-registered with CT images for IMRT planning. Three planning target volumes were defined: PTV_risk, PTV_{pre_chemo} and PTV_{post_chemo}. For SIB, prescribed mean doses to the PTVs were 46, 50 and 58 Gy, respectively, given in 25 fractions. Organs at risk (OARs) were bladder and intestine. The novel three-volume SIB strategy was compared to a conventional two-volume SIB plan, in which PTV_{post_chemo} was ignored, using dose-volume histograms (DVHs) and the generalized equivalent uniform dose (gEUD).

Results

All patients showed tumor shrinkage following chemotherapy. For the novel SIB, population-based mean doses given to PTV_risk, PTV_{pre_chemo} and PTV_{post_chemo} were 46.8 ± 0.3, 50.6 ± 0.4 and 58.1 ± 0.4 Gy, respectively. DVHs and gEUDs for PTV_risk, PTV_{pre_chemo}, bladder and intestine revealed minimal differences between the two SIB strategies.

Conclusions

Tumor volume reduction for rectal cancer patients following neoadjuvant chemotherapy allows for increased tumor dose using a SIB strategy without increased OAR toxicity.     

Decline of dose coverage between intraoperative planning and post implant dosimetry for I-125 permanent prostate brachytherapy: Comparison between loose and stranded seed implants

Background and purpose

In permanent prostate brachytherapy the dose distributions 4 weeks post implant differ from the intraoperative dose distributions. The purpose of this study is to compare intraoperative planning and post implant dosimetry for loose and stranded seed implants.

Materials and methods

This study investigates prostate dose coverage in 389 patients with stage T1 or T2 prostate cancer treated in the years 2005, 2006 and 2007. The patients received either a loose seed or a stranded seed implant. All patients had US-based intraoperative planning and CT/MRI-based post implant dosimetry after 4 weeks.

Results

Intraoperative and post implant D₉₀ values amounted 183 ± 13 Gy (mean ± standard deviation) and 161 ± 30 Gy, respectively. Decline of D₉₀ values (mean and 95% confidence interval) between intraoperative planning and post implant dosimetry for RAPID strand (n = 67), Intersource strand (n = 136) and loose selectSeeds (n = 186) implants amounted to −40 (−45 to −34) Gy, −25 (−28 to −21) Gy and −15 (−18 to −21) Gy, respectively.

Conclusions

The patients treated in the period 2005-2007 with stranded or loose seed implants had on average adequate D₉₀ values of 161 ± 30 Gy. Post implant D₉₀ values were 22 ± 27 Gy lower compared to intraoperative planning. Decline of dose coverage between intraoperative planning and post implant dosimetry was significantly larger for the stranded seed implants.     

Is pre-therapeutical FDG-PET/CT capable to detect high risk tumor subvolumes responsible for local failure in non-small cell lung cancer?

Background and purpose

Local failure is a significant issue following radiotherapy (RT) for patients with non-small cell lung cancer (NSCLC). The aim of this study was to find out whether FDG-PET/CT is capable to predict tumor relapse location in patients with NSCLC, in particular to determine high risk tumors’ subvolumes responsible for local failure.

Material and methods

Ten patients with locoregional relapse of NSCLC underwent FDG-PET/CT before, during, and in the 4-12 months following curative chemoradiotherapy (ChRT, 66 Gy) using a combined PET/CT scanner. Morphologic and metabolic tumor volumetry and an evaluation of FDG-uptake dynamics were performed.

Results

CT showed partial reduction of tumor volume after RT in all patients. PET-revealed partial in eight patients and complete metabolic response in two patients during RT. Six to nine months after RT, local failure was diagnosed in all patients with both methods. Tumor recurrences were localized mostly in the most active ones of pre-therapeutically metabolic regions of the primary tumor.

Conclusions

Local failure in NSCLC appears most common at the primary site and within the irradiated target volume with the highest FDG uptake. This observation may be useful for further optimization of radiotherapy of NSCLC, for example, by the application of additional radiation dose to subvolumes of primary tumors with higher FDG uptake.     

Impact of PARP-1 and DNA-PK expression on survival in patients with glioblastoma multiforme

Purpose

To analyze, whether higher tumor levels of DNA repair enzymes contribute to worse treatment results of glioblastoma multiforme (GBM) patients after postoperative radiotherapy.

Materials and methods

Thirty four patients with GBM received postoperative radiotherapy. Tumor sections were examined for poly-ADP ribose polymerase-1 (PARP-1) and DNA protein kinase (DNA-PK) expression. Immunohistochemical staining intensities of PARP-1 and DNA-PK were determined (score 0-3) and expression levels were correlated with patients overall survival.

Results

Median survival time of the whole study group was 10.0 months (95% CI 8.1-11.9). Median survival of patients with high and low (?median and <median) tumor PARP-1 levels were 10.0 months (95% CI 7.9-12.1) and 12.0 months (95% CI 8.3-15.7), respectively (p = 0.93). In contrast, median survival of patients with high and low tumor DNA-PK levels were 9.0 months (95% CI 7.2-10.8) and 13.0 months (95% CI 10.7-15.3), respectively (p = 0.02). In multivariate analysis, DNA-PK expression emerged as a significant independent predictor for overall survival (HR 3.9, 95% CI 1.5-10.7, p = 0.01).

Conclusion

This hypothesis generating study showed that high tumor levels of DNA-PK correlate with poor survival of GBM patients. Further studies are needed to confirm these results and to clarify whether DNA-PK inhibitors might have a potential to radiosensitize GBM and improve the treatment outcome of this devastating disease.     

Dose escalation in the radiotherapy of non-small-cell lung cancer with aperture-based intensity modulation and photon beam energy optimization for non-preselected patients

Purpose

To verify the potential of aperture-based intensity-modulated radiotherapy (AB-IMRT) to realize dose escalation plans for non-preselected non-small-cell lung cancer (NSCLC) patients, using photon beam energy optimization.

Methods and materials

Seven cases of NSCLC were retrospectively studied. Clinical reference plans were made at 60 Gy by an experienced dosimetrist. Dose escalation was applied to PTV2, a subvolume within the main PTV1. Escalation plans were optimized by considering beam angles (table and gantry), energy (6 and 23 MV) and weights, for an increasing dose to the PTV2, starting from 66 Gy and keeping 30 fractions.

Results

In five cases, doses over 78 Gy could be achieved before exceeding organs at risk (OARs) standard tolerance. Peripheral overdosages, as well as lung and spinal cord tolerance doses, limited escalation. Means ± SD V_95% parameters were (97.3 ± 0.9)% for PTV1s and (96.7 ± 2.2)% for PTV2s. Doses to OARs were also maintained at acceptable levels. Optimized plans made use of both low- and high-energy beams and had a similar number of monitor units compared to the 60 Gy clinical plans.

Conclusions

The AB-IMRT system can successfully realize dose escalation for a sizeable number of cases. Plans produced contained few large segments, and are applicable to a wide range of tumor volumes and locations.     

A sulindac analogue is effective against malignant pleural effusion in mice

Objectives

To examine whether a sulindac derivative (C-18) with previously reported anti-angiogenic properties limits malignant pleural effusion (MPE) formation in mice.

Methods

MPE was generated by intrapleural injection of murine adenocarcinoma cells in C57BL/6 mice. Animals were divided into three groups, a control group and two treatment groups receiving intraperitoneally a daily dose of either 1 mg or 2 mg of C-18 for a total of 12 doses. Mice were sacrificed on day 14.

Measurements and main results

Pleural fluid volume and the number of pleural tumor implantations were measured. Tumor angiogenesis, pleural vascular permeability and the host inflammatory response were also assessed. C-18 significantly limited pleural fluid formation and inhibited intrapleural tumor dissemination. The mean ± SEM pleural fluid volume was 758 ± 63 μl for the control group, compared to 492 ± 120 μl (p = 0.042) and 279 ± 77 μl (p < 0.001) for the low dose and high dose group of C-18, respectively. Control group animals had 6.2 ± 1 intrapleural tumors, while C-18 treated animals had 3.1 ± 0.8 (p = 0.014) and 3 ± 0.7 (p = 0.009) for the low and high dose respectively. In addition C-18 significantly suppressed pleural vascular permeability. No significant difference in tumor angiogenesis and inflammatory response was observed, while there was also no measurable effect in tumor cell apoptosis and proliferation in vitro and in vivo.

Conclusions

C-18 halted experimental MPE formation and intrapleural tumor dissemination, through down-regulation of pleural vascular permeability.     

Radiographic and metabolic response rates following image-guided stereotactic radiotherapy for lung tumors

Purpose

To evaluate radiographic and metabolic response after stereotactic body radiotherapy (SBRT) for early lung tumors.

Materials and methods

Thirty-nine tumors were treated prospectively with SBRT (dose = 48-60 Gy, 4-5 Fx). Thirty-six cases were primary NSCLC (T1N0 = 67%; T2N0 = 25%); three cases were solitary metastases. Patients were followed using CT and PET at 6, 16, and 52 weeks post-SBRT, with CT follow-up thereafter. RECIST and EORTC criteria were used to evaluate CT and PET responses.

Results

At median follow-up of 9 months (0.4-26), RECIST complete response (CR), partial response (PR), and stable disease (SD) rates were 3%, 43%, 54% at 6 weeks; 15%, 38%, 46% at 16 weeks; 27%, 64%, 9% at 52 weeks. Mean baseline tumor volume was reduced by 46%, 70%, 87%, and 96%, respectively at 6, 16, 52, and 72 weeks. Mean baseline maximum standardized uptake value (SUV) was 8.3 (1.1-20.3) and reduced to 3.4, 3.0, and 3.7 at 6, 16, and 52 weeks after SBRT. EORTC metabolic CR/PR, SD, and progressive disease rates were 67%, 22%, 11% at 6 weeks; 86%, 10%, 3% at 16 weeks; 95%, 5%, 0% at 52 weeks.

Conclusions

SBRT yields excellent RECIST and EORTC based response. Metabolic response is rapid however radiographic response occurs even after 1-year post treatment.     

HDR endobronchial brachytherapy (HDRBT) in the management of advanced lung cancer - Comparison of two different dose schedules

Purpose

The aim of this work is to compare the results of various treatment protocols used in palliative HDRBT with the view of analyzing differences in survival and diminishing breathing difficulties.

Material and methods

A total of 648 patients with advanced lung cancer were divided into two groups according to their clinical stage and the Zubrod-ECOG-WHO score. 303 (46.8%) patients received a total dose of 22.5 Gy in 3 fractions once a week, and 345 (53.2%) patients received a single fraction of 10 Gy. They were under clinical and endobronchial observation taking into consideration survival rates, local remission and duration of symptom relief such as dyspnoea, breathing, cough and haemoptysis.

Results

There was no difference in the length of survival time between the two groups of patients (log-rank test, p = 0.055). Patients showing improvement (objective response) survived longer than those who showed no change or progression (F Cox, p = 0.000001). In multivariate analysis the other statistically important prognostic factors were: clinical stage of primary tumor (F Cox, p = 0.000002), Zubrod-ECOG-WHO score (F Cox, p = 0.002) and age of patients (F Cox, p = 0.004).

Conclusions

The two treatment protocols showed similar efficiency in overcoming difficulties in breathing. Prognostic factors that significantly correlated with survival length were: grade of remission after treatment, clinical stage and performance status.