Prospective study on stereotactic radiotherapy of limited-stage non–small-cell lung cancer

Stereotactic body radiation therapy for early stage non-small cell lung cancer: results of a prospective trial

Patients affected with early stage (IA-IB) non-small cell lung cancer (NSCLC), deemed medically inoperable, are usually treated by conventional 3D-CRT, with poor results in terms of local tumour control and survival. Hypofractionated stereotactic body radiation therapy (SBRT) appears to be a valid alternative option, with high rates of local control and promising survival rates according to recent reported series. We herein report the final results of a prospective phase II trial of SBRT in 62 stage I NSCLC patients, homogeneously treated with three fractions of 15Gy each, given every other day during a 1 week time, up to a total dose of 45Gy; dose was prescribed to the 80%-isodose encompassing planning target volume. Patients were immobilized in a dedicated stereotactic body frame; margins around gross tumour volume were 5mm in the axial plane and 10mm in the longitudinal direction. Median age was 73.7 years. A pathologic confirmation of NSCLC was obtained in 64.5% of patients. Forty-three patients had stage IA and 19 stage IB disease. The majority of patients did not experience any toxicity; mild skin reactions, fatigue, dyspnea/cough or transient thoracic pain were recorded in approximately 10% of patients. With a median follow-up time of 28 months, 2 patients experienced an isolated local relapse, 4 an isolated nodal relapse and 15 a systemic failure. At 3 years, local control rate was 87.8%, cancer-specific survival 72.5%, overall survival 57.1%, with 8 out of 20 non-cancer related deaths. In multivariate analysis, tumour volume was associated with a better outcome. In our series, SBRT was well tolerated and confirmed its efficacy, with local control and survival rates globally superior to those reported using conventional radiotherapy. A longer follow-up is needed in order to establish a correct comparison with surgical series, and to fully ascertain a potential negative impact of SBRT on comorbidities of such a fragile patients population.

Outcome in a prospective phase II trial of medically inoperable stage I non-small-cell lung cancer patients treated with stereotactic body radiotherapy

PURPOSE

The impact of stereotactic body radiotherapy (SBRT) on 3-year progression-free survival of medically inoperable patients with stage I non-small-cell lung cancer (NSCLC) was analyzed in a prospective phase II study.

PATIENTS AND METHODS

Fifty-seven patients with T1NOMO (70%) and T2N0M0 (30%) were included between August 2003 and September 2005 at seven different centers in Sweden, Norway, and Denmark and observed up to 36 months. SBRT was delivered with 15 Gy times three at the 67% isodose of the planning target volume.

RESULTS

Progression-free survival at 3 years was 52%. Overall- and cancer-specific survival at 1, 2, and 3 years was 86%, 65%, 60%, and 93%, 88%, 88%, respectively. There was no statistically significant difference in survival between patients with T1 or T2 tumors. At a median follow-up of 35 months (range, 4 to 47 months), 27 patients (47%) were deceased, seven as a result of lung cancer and 20 as a result of concurrent disease. Kaplan-Meier estimated local control at 3 years was 92%. Local relapse was observed in four patients (7%). Regional relapse was observed in three patients (5%). Nine patients (16%) developed distant metastases. The estimated risk of all failure (local, regional, or distant metastases) was increased in patients with T2 (41%) compared with those with T1 (18%) tumors (P = .027).

CONCLUSION

With a 3-year local tumor control rate higher than 90% with limited toxicity, SBRT emerges as state-of-the-art treatment for medically inoperable stage I NSCLC and may even challenge surgery in operable instances.

Radiation safety issues with positron-emission/computed tomography simulation for stereotactic body radiation therapy

Stereotactic body radiation therapy (SBRT) simulations using a Stereotactic Body Frame (SBF: Elekta, Stockholm, Sweden) were expanded to include 18F-deoxyglucosone positron-emission tomography (FDG PET) for treatment planning. Because of the length of time that staff members are in close proximity to the patient, concerns arose over the radiation safety issues associated with these simulations. The present study examines the radiation exposures of the staff performing SBRT simulations, and provides some guidance on limiting staff exposure during these simulations. Fifteen patients were simulated with PET/CT using the SBF. Patients were immobilized in the SBF before the FDG was administered. The patients were removed from the frame, injected with FDG, and allowed to uptake for approximately 45 minutes. After uptake, the patients were repositioned in the SBF. During the repositioning, exposure rates were recorded at the patient's surface, at the SBF surface, and at 15 cm, 30 cm, and 1 m from the SBF. Administered dose and the approximate time spent on patient repositioning were also recorded. The estimated dose to staff was compared with the dose to staff performing conventional diagnostic PET studies. The average length of time spent in close proximity (<50 cm) to the patient after injection was 11.7 minutes, or more than twice the length of time reported for diagnostic PET staff. That time yielded an estimated average dose to the staff of 26.5 microSv per simulation. The annual occupational exposure limit is 50 mSv. Based on dose per simulation, staff would have to perform nearly 1900 SBRT simulations annually to exceed the occupational limit. Therefore, at the current rate of 50-100 simulations annually, the addition of PET studies to SBRT simulations is safe for our staff. However, ALARA ("as low as reasonably achievable") principles still require some radiation safety considerations during SBRT simulations. The PET/CT-based SBRT simulations are safe and important for treatment planning that optimizes biologic dose distribution with highly accurate and reproducible target definition.

An evaluation of planning techniques for stereotactic body radiation therapy in lung tumors

PURPOSE

To evaluate four planning techniques for stereotactic body radiation therapy (SBRT) in lung tumors.

METHODS AND MATERIALS

Four SBRT plans were performed for 12 patients with stage I/II non-small-cell lung cancer under the following conditions: (1) conventional margins on free-breathing CT (plan 1), (2) generation of an internal target volume (ITV) using 4DCT with beam delivery under free-breathing conditions (plan 2), (3) gating at end-exhale (plan 3), and (4) gating at end-inhale (plan 4). Planning was performed following the RTOG 0236 protocol with a prescription dose of 54 Gy (3 fractions). For each plan 4D dose was calculated using deformable-image registration.

RESULTS

There was no significant difference in tumor dose delivered by the 4 plans. However, compared with plan 1, plans 2-4 reduced total lung BED by 1.9+/-1.2, 3.1+/-1.6 and 3.5+/-2.1 Gy, reduced mean lung dose by 0.8+/-0.5, 1.5+/-0.8, and 1.6+/-1.0 Gy, reduced V20 by 1.5+/-1.0%, 2.7+/-1.4%, and 2.8+/-1.8%, respectively, with p<0.01. Compared with plan 2, plans 3-4 reduced lung BED by 1.2+/-1.0 and 1.6+/-1.5 Gy, reduced mean lung dose by 0.6+/-0.5 and 0.8+/-0.7 Gy, reduced V20 by 1.2+/-1.1% and 1.3+/-1.5%, respectively, with p<0.01. The differences in lung BED, mean dose and V20 of plan 4 compared with plan 3 were insignificant.

CONCLUSIONS

Tumor dose coverage was statistically insignificant between all plans. However, compared with plan 1, plans 2-4 significantly reduced lung doses. Compared with plan 2, plan 3-4 also reduced lung toxicity. The difference in lung doses between plan 3 and plan 4 was not significant.

Hypofractionated stereotactic radiotherapy for medically inoperable stage I non-small cell lung cancer--report on clinical outcome and dose to critical organs

We report 20 cases using hypofractionation stereotactic radiotherapy in medically inoperable stage I non-small cell lung cancer with dose escalation of 45-54 Gy prescribed at 85 or 90% isodose level in 3-4 fractions. Two-year local control and cancer-specific survival were 94.7 and 77.6%, respectively, with minimal toxicity. Though, large fraction size can be safely given to peripheral lung tumors, normal tissue tolerance to hypofractionated radiotherapy to esophagus, trachea, main bronchi, aorta and heart remains unknown. Therefore we also reported the maximum point doses to these critical organs to contribute information to extend this technique to more centrally located lung tumors in future.

Proton therapy in lung cancer: clinical outcomes and technical issues. A systematic review

BACKGROUND AND PURPOSE

To determine whether, according to the currently available literature, proton therapy (PT) has a role in the treatment of non-small-cell lung cancer (NSCLC), to assess its safety and efficacy and to evaluate the main technical issues specifically related to this treatment technique.

MATERIALS AND METHODS

During March 2007, two independent researchers conducted a systematic review of the current data on the treatment of NSCLC with PT.

RESULTS

In total, 113 reports were retrieved, 17 of which were included in the analysis. There were no prospective trials (randomized or non-randomized). Nine uncontrolled single-arm studies were available from three PT centers, providing clinical outcomes for 214 patients in total. These reports were mainly related to stage I-II tumors, with results comparable to those obtained with surgery, without significant toxicity. In addition, two papers were found that compared photon and proton dose distributions, which showed a potential for dose escalation and/or a sparing of the organ at risk with PT. Finally, six studies analyzed dosimetric and technical issues related with PT, mainly underlining the difficulties in designing dose distributions that are representative of the dose actually delivered during treatment.

CONCLUSIONS

Although from a physical point of view PT is a good option for the treatment of NSCLC, limited data are available on its application in the clinical practice. Furthermore, the application of PT to lung cancer does present technical challenges. Because of the small number of institutions involved in the treatment of this disease, number of patients, and methodological weaknesses of the trials it is therefore not possible to draw definitive conclusions about the superiority of PT with respect to the photon techniques currently available for the treatment of NSCLC.

A phase II study on stereotactic body radiotherapy for stage I non-small cell lung cancer

BACKGROUND AND PURPOSE

The outcome of stage I non-small cell lung cancer (NSCLC) patients treated with conventional radiotherapy is inferior to that of patients treated surgically. We aimed to evaluate the clinical outcome of stereotactic body radiotherapy (SBRT) in the treatment of stage I NSCLC.

MATERIALS AND METHODS

We performed SBRT for 31 stage I NSCLC patients. Of these, 20 were medically inoperable, and 11 refused surgery. Nineteen tumours were T1-stage masses, and 12 tumours were T2. Median tumour size was 25 mm. SBRT was administered as 45 Gy/3 fractions; however, when the tumour was close to an organ at risk, 60 Gy/8 fractions were used. These doses were prescribed at the centre of the tumours.

RESULTS

The median duration of observation for all patients was 32 months (range, 4-87 months). In 9 of the 31 cases, local recurrence was observed. The 3-year local control rates of T1 and T2 tumours were 77.9% and 40.0%, respectively. The 3-year overall and cause-specific survival rates were 71.7% and 83.5%, respectively. Although the symptoms improved with medical treatment, 5 patients developed acute pulmonary toxicity > or =grade 2.

CONCLUSIONS

SBRT is safe and effective for stage I NSCLC patients. However, a more intensive treatment regimen should be considered for T2 tumours.

Quantification of incidental dose to potential clinical target volume (CTV) under different stereotactic body radiation therapy (SBRT) techniques for non-small cell lung cancer – Tumor motion and using internal target volume (ITV) could improve dose distribution in CTV

PURPOSE

Clinical target volume (CTV), although present, is usually not considered during stereotactic body radiation therapy (SBRT) for non-small cell lung cancer. This study aimed to quantify the incidental dose to the potential CTV under different SBRT techniques.

MATERIALS AND METHODS

Ten patients with various tumor motions were included in the study. Gated-4DCT was performed for all patients. Three treatment plans were generated. Plan A was based on free breathing gross tumor volume (GTV) from a regular CT. Plan B was based on internal target volume (ITV) from gated 4DCT. Plan C was a perfect gated treatment at the exhale phase. The hypothetical CTV was represented by three CTV shells (5, 10, and 15 mm). Time-averaged dose for different respiratory phases was calculated for 18 representative points in each shell.

RESULTS

The minimum doses for plans A, B, and C were 84+/-20%, 94+/-3%, and 80+/-17% of the isocenter dose to the 5mm shell, 72+/-27%, 64+/-7%, and 20+/-11% to the 10mm shell, and 38+/-27%, 27+/-17%, and 6+/-7% to the 15 mm shell, respectively. The caudal and cranial ends of each shell usually had lower dose compared to the other points on the shell. Plan B had the most uniform and reasonable doses to the CTV shells, and patients with large respiratory motion had significantly higher minimum dose than patients with less motion.

CONCLUSION

The potential CTV may incidentally receive adequate and relatively homogeneous doses when ITV is used and the patients have large respiratory motion. However, it could be underdosed for gated treatment or for patients with little motion.

Radical stereotactic radiosurgery with real-time tumor motion tracking in the treatment of small peripheral lung tumors

Background

Recent developments in radiotherapeutic technology have resulted in a new approach to treating patients with localized lung cancer. We report preliminary clinical outcomes using stereotactic radiosurgery with real-time tumor motion tracking to treat small peripheral lung tumors.

Methods

Eligible patients were treated over a 24-month period and followed for a minimum of 6 months. Fiducials (3–5) were placed in or near tumors under CT-guidance. Non-isocentric treatment plans with 5-mm margins were generated. Patients received 45–60 Gy in 3 equal fractions delivered in less than 2 weeks. CT imaging and routine pulmonary function tests were completed at 3, 6, 12, 18, 24 and 30 months.

Results

Twenty-four consecutive patients were treated, 15 with stage I lung cancer and 9 with single lung metastases. Pneumothorax was a complication of fiducial placement in 7 patients, requiring tube thoracostomy in 4. All patients completed radiation treatment with minimal discomfort, few acute side effects and no procedure-related mortalities. Following treatment transient chest wall discomfort, typically lasting several weeks, developed in 7 of 11 patients with lesions within 5 mm of the pleura. Grade III pneumonitis was seen in 2 patients, one with prior conventional thoracic irradiation and the other treated with concurrent Gefitinib. A small statistically significant decline in the mean % predicted DLCO was observed at 6 and 12 months. All tumors responded to treatment at 3 months and local failure was seen in only 2 single metastases. There have been no regional lymph node recurrences. At a median follow-up of 12 months, the crude survival rate is 83%, with 3 deaths due to co-morbidities and 1 secondary to metastatic disease.

Conclusion

Radical stereotactic radiosurgery with real-time tumor motion tracking is a promising well-tolerated treatment option for small peripheral lung tumors.

A feasibility study of image-guided hypofractionated conformal arc therapy for inoperable patients with localized non-small cell lung cancer

We treated 36 cases of stage I/II non-small cell lung cancer in inoperable patients. Treatments were planned to a total isocenter dose of 60Gy (8x7.5Gy) based on a dynamic field shaping arc, employing one arc to span as much area as possible and if needed additional weighted segments. The 2 year infield progression free probability is 65%. Disease-specific survival is 75% at 2 years. No patients experienced grade 3-4 toxicity.