Steep dose-response relationship for stage I non-small-cell lung cancer using hypofractionated high-dose irradiation by real-time tumor-tracking radiotherapy

Comprehensive analysis of pulmonary function Test (PFT) changes after stereotactic body radiotherapy (SBRT) for stage I lung cancer in medically inoperable patients

BACKGROUND

To assess for variables predicting pulmonary function test (PFT) changes after stereotactic body radiotherapy (SBRT) for medically inoperable stage I lung cancer.

METHODS

We reviewed 92 consecutive patients undergoing SBRT for stage I lung cancer between February 2004 and August 2007. A total of 102 lesions were treated using prescriptions of 20 Gy x 3 (n = 40), 10 Gy x 5 (n = 56), and 5 Gy x 10 (n = 6). Institutional practice was 10 Gy x 5 before March 1, 2006 before changing to 20 Gy x 3 to conform to RTOG 0236 unless otherwise dictated clinically.

RESULTS

Median pretreatment forced expiratory volume at 1 second (FEV1) was 1.21 liter (50% of predicted) and median diffusion capacity to carbon monoxide (DLCO) was 56.5. There was no significant overall change in PFT's after SBRT. Individual patients experienced both substantial improvements and declines (10% declined at least 14% predicted FEV1% and 19% predicted DLCO). The mean change in FEV1 was -0.05 liter (range, -0.98 to +1.29 liter; p = 0.22) representing -1.88% predicted baseline FEV1 (range, -33 to + 43%; p = 0.62). DLCO declined 2.59% of predicted (range, -37 to +33%; p = 0.27). Conformality index, V5 and V10 were associated with individual patient changes in FEV1% (p = 0.033, p = 0.0036, p = 0.025, respectively), however, correlations were small and overall treatment dose did not predict for changes (p = 0.95). There was no significant difference in FEV1 (p = 0.55) or FEV1% (p = 0.37) changes for central versus peripheral locations. No factors predicted for individual changes in DLCO. Patients with FEV1% below the median of the study population had significantly longer overall survival (p = 0.0065). Although patients dying of cardiac disease died earlier than those dying of other causes, FEV1% below median was not associated with a lower risk of dying of cardiac disease or with lower Charlson comorbidity index.

CONCLUSIONS

(1) SBRT was well tolerated and PFT changes were minimal. (2) Central lesions were safely treated with 50 Gy.

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.

Quantifying interfraction and intrafraction tumor motion in lung stereotactic body radiotherapy using respiration-correlated cone beam computed tomography

PURPOSE

Stereotactic body radiation therapy (SBRT) is an effective treatment for medically inoperable Stage I non-small-cell lung cancer. However, changes in the patient's breathing patterns during the course of SBRT may result in a geographic miss or an overexposure of healthy tissues to radiation. However, the precise extent of these changes in breathing pattern is not well known. We evaluated the inter- and intrafractional changes in tumor motion amplitude (DeltaM) over an SBRT course.

METHODS AND MATERIALS

Eighteen patients received image-guided SBRT delivered in three fractions; this therapy was done with abdominal compression in four patients. For each fraction, cone beam computed tomography (CBCT) was performed for tumor localization (+/- 3-mm tolerance) and then repeated to confirm geometric accuracy. Additional CBCT images were acquired at the midpoint and end of each SBRT fraction. Respiration-correlated CBCT (rcCBCT) reconstructions allowed retrospective assessment of inter- and intrafractional DeltaM by a comparison of tumor displacements in all four-dimensional CT and rcCBCT scans. The DeltaM was measured in mediolateral, superior-inferior, and anterior-posterior directions.

RESULTS

A total of 201 rcCBCT images were analyzed. The mean time from localization of the tumor to the end-fraction CBCT was 35 +/- 7 min. Compared with the motion recorded on four-dimensional CT, the mean DeltaM was 0.4, 1.0, and 0.4 mm, respectively, in the mediolateral, superior-inferior, and anterior-posterior directions. On treatment, the observed DeltaM was, on average, <1 mm; no DeltaM was statistically different with respect to the initial rcCBCT. However, patients in whom abdominal compression was used showed a statistically significant difference (p < 0.05) in the variance of DeltaM with respect to the initial rcCBCT in the superior-inferior direction.

CONCLUSIONS

The inter- and intrafractional DeltaM that occur during a course of lung SBRT are small. However, abdominal compression causes larger variations in the time spent on the treatment couch and in the inter- and intrafractional DeltaM values.

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 > or = 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.

Clinical outcomes of stereotactic body radiotherapy for small lung lesions clinically diagnosed as primary lung cancer on radiologic examination

PURPOSE

Image-guided biopsy occasionally fails to diagnose small lung lesions, which are highly suggestive of primary lung cancer. The aim of the present study was to evaluate the outcome of stereotactic body radiotherapy (SBRT) for small lung lesions that were clinically diagnosed as primary lung cancer without pathologic confirmation.

METHODS AND MATERIALS

A total of 115 patients were treated with SBRT in 12 institutions. Tumor size ranged from 5 to 45 mm in diameter, with a median of 20 mm.

RESULTS

The 3-year and 5-year overall survival rates for patients with a tumor size < or =20 mm in diameter (n = 58) were both 89.8%, compared with 60.7% and 53.1% for patients with tumors >20 mm (n = 57) (p <0.0005), respectively. Local progression occurred in 2 patients (3.4%) with a tumor size < or =20 mm and in 3 patients (5.3%) with tumors >20 mm. Among the patients with a tumor size < or =20 mm, Grade 2 pulmonary complications were observed in 2 (3.4%), but no Grade 3 to 5 toxicity was observed. In patients with a tumor size >20 mm, Grades 2, 3, and 5 toxicity were observed in 5 patients (8.8%), 3 patients (5.3%), and 1 patient (1.8%), respectively.

CONCLUSION

In patients with a tumor < or =20 mm in diameter, SBRT was reasonably safe in this retrospective study. The clinical implications of the high local control rate depend on the accuracy of clinical/radiologic diagnosis for small lung lesions and are to be carefully evaluated in a prospective study.

Stereotactic body radiation therapy in centrally and superiorly located stage I or isolated recurrent non-small-cell lung cancer

PURPOSE

To evaluate the efficacy and adverse effects of image-guided stereotactic body radiation therapy (SBRT) in centrally/superiorly located non-small-cell lung cancer (NSCLC).

MATERIALS AND METHODS

We delivered SBRT to 27 patients, 13 with Stage I and 14 with isolated recurrent NSCLC. A central/superior location was defined as being within 2 cm of the bronchial tree, major vessels, esophagus, heart, trachea, pericardium, brachial plexus, or vertebral body, but 1 cm away from the spinal canal. All patients underwent four-dimensional computed tomography-based planning, and daily computed tomography-on-rail guided SBRT. The prescribed dose of 40 Gy (n = 7) to the planning target volume was escalated to 50 Gy (n = 20) in 4 consecutive days.

RESULTS

With a median follow-up of 17 months (range, 6-40 months), the crude local control at the treated site was 100% using 50 Gy. However, 3 of 7 patients had local recurrences when treated using 40 Gy. Of the patients with Stage I disease, 1 (7.7%) and 2 (15.4%) developed mediastinal lymph node metastasis and distant metastases, respectively. Of the patients with recurrent disease, 3 (21.4%) and 5 (35.7%) developed mediastinal lymph node metastasis and distant metastasis, respectively. Four patients (28.6%) with recurrent disease but none with Stage I disease developed Grade 2 pneumonitis. Three patients (11.1%) developed Grade 2-3 dermatitis and chest wall pain. One patient developed brachial plexus neuropathy. No esophagitis was noted in any patient.

CONCLUSIONS

Image-guided SBRT using 50 Gy delivered in four fractions is feasible and resulted in excellent local control.

Normal tissue toxicity after small field hypofractionated stereotactic body radiation

Stereotactic body radiation (SBRT) is an emerging tool in radiation oncology in which the targeting accuracy is improved via the detection and processing of a three-dimensional coordinate system that is aligned to the target. With improved targeting accuracy, SBRT allows for the minimization of normal tissue volume exposed to high radiation dose as well as the escalation of fractional dose delivery. The goal of SBRT is to minimize toxicity while maximizing tumor control. This review will discuss the basic principles of SBRT, the radiobiology of hypofractionated radiation and the outcome from published clinical trials of SBRT, with a focus on late toxicity after SBRT. While clinical data has shown SBRT to be safe in most circumstances, more data is needed to refine the ideal dose-volume metrics.

Observation of a dose-control relationship for lung and liver tumors after stereotactic body radiation therapy

PURPOSE

To determine prognostic factors for local control of primary or metastatic tumors within the lung or liver treated with stereotactic body radiation therapy (SBRT) within a single institution.

METHODS AND MATERIALS

The records of 141 consecutive patients with 246 lesions treated with three-fraction SBRT from Oct 1999 through Aug 2005 were reviewed. Local control was assessed radiographically. Univariate and multivariate analyses were performed to evaluate the influence of the following factors on local control: total dose, expressed as either nominal prescription dose or equivalent uniform dose (EUD); gross tumor volume; primary site; treatment site (lung vs. other); histologic characteristics (adenocarcinoma vs. other); gender; age; and primary vs. metastatic tumor.

RESULTS

On univariate analysis, increased dose (either nominal or EUD) and smaller gross tumor volume were significant predictors of higher local control. Lesions treated to a nominal dose of 54 Gy or greater had a 3-year actuarial local control rate of 89.3% compared with 59.0% and 8.1% for those treated to 36-53.9 Gy and less than 36 Gy. On multivariate analysis, only increased nominal dose and EUD retained statistical significance. Treatment was well tolerated; 5.7% of patients experienced Grade 3 or higher toxicity.

CONCLUSIONS

This large single-institution series suggests a dose-control relationship within the range of SBRT doses applied. Excellent local control rates are achieved with a nominal dose of 54 Gy or greater, corresponding to an EUD greater than 65.3 Gy. These results support the use of aggressive SBRT regimens when durable tumor control is the primary objective.

Can stereotactic fractionated radiation therapy become the standard of care for early stage non-small cell lung carcinoma

Management of early stages non-small cell lung carcinoma has traditionally been surgery with radiation selected for medically inoperable patients. Recent emergence of stereotactic body radiation therapy allows for delivery of high radiation dose to the tumor while sparing normal lungs. This reviews compares loco-regional control, survival and complications rates between these two treatment modalities. Literature search identifies studies with stereotactic body radiation therapy and surgery for early stages non-small cell lung cancer. Effectiveness and toxicity of these two modalities was assessed. Stereotactic body radiation therapy is associated with minimal morbidity and provides comparable local control and survival in patients with multiple co-morbidities factors. Stereotactic body radiation therapy may become standard of care for operable early stages non-small cell lung cancer.

Exploring the role of cancer stem cells in radioresistance

Radiobiological research over the past decades has provided evidence that cancer stem cell content and the intrinsic radiosensitivity of cancer stem cells varies between tumours, thereby affecting their radiocurability. Translation of this knowledge into predictive tests for the clinic has so far been hampered by the lack of methods to discriminate between stem cells and non-stem cells. New technologies allow isolation of cells expressing specific surface markers that are differentially expressed in tumour cell subpopulations that are enriched for cancer stem cells. Combining these techniques with functional radiobiological assays holds the potential to elucidate the role of cancer stem cells in radioresistance in individual tumours, and to use this knowledge for the development of predictive markers for optimization of radiotherapy.