International Journal of Radiation Oncology*Biology*Physics
Clinical InvestigationPulmonary Function Testing After Stereotactic Body Radiotherapy to the Lung
Introduction
Although surgical resection remains the standard of care for operable early-stage non–small-cell lung cancer (NSCLC), a promising alternative, especially for patients unfit for the operating room, is stereotactic body radiotherapy (SBRT). The technique involves the delivery of high-dose radiation precisely to the area of the lung where the tumor is located. Multiple studies have found SBRT feasible at different doses, with tumor control rates up to 90% 1, 2, 3, 4, 5. In a Phase II study, comorbidities such as cardiovascular disease and chronic obstructive pulmonary disease (COPD) for patients undergoing SBRT were examined (6). The authors found good local control of the cancer with low overall toxicity. That same group, in 2009, reported very favorable tumor control rates after 3 years of initial SBRT (7). As SBRT continues to become more popular as both an option for patients unfit for surgery and even an alternative for surgical treatment, a better understanding of the implications of its effect on lung function for patients with and without COPD is necessary. We set out to compare patients’ pulmonary function before and after SBRT and to stratify these patients based on their baseline COPD status.
Section snippets
Patients
All patients were evaluated in a university hospital multidisciplinary lung cancer evaluation center and were diagnosed with Stage I biopsy-proven NSCLC. All patients were considered unfit for surgical treatment according to the consensus of a tumor board according to the criteria of the American College of Surgeons Oncology Group (https://www.acosog.org/). Staging of the cancer was accomplished by positron emission tomography/computed tomography and bronchoscopy with biopsy of the
Results
A total of 30 patients had a complete set of PFTs before and after SBRT. Of those, 7 had COPD (4 men, 3 women) and 23 did not have COPD (9 men, 14 women). The mean age for the COPD vs. the No-COPD group was 75 ± 7.8 vs. 77 ± 8.7 years, respectively (Table 1, Table 2, Table 3). The time between SBRT and follow-up PFT was similar in both groups: 112 ± 67.5 days for the COPD group and 112 ± 53 days for the No-COPD group. Using the Mann-Whitney U test, pretreatment FEV1 and FVC percent of predicted
Discussion
The use of SBRT in North America has been limited to medically inoperable patients. These patients present with a higher number of comorbidities, and that has a direct impact on their long-term survival. Inoue et al. (8) reported that for tumors ≤20 mm in diameter, SBRT had safe outcomes, with a 3-year survival rate of 89.9%. Several studies have been made of inoperable patients with 2- to 3-year local control rates of more than 80% 1, 2, 3, 4, 5. Despite their overall poor health, more than
Conclusion
The literature now contains several studies showing either a slight improvement or a slight decline in pulmonary function (10–15%) up to a year after SBRT. Interestingly, no study, as far as we are aware, has yet shown a crossover (i.e., an initial gain resulting in a loss or vice versa). In our data, SBRT did not seem to have a deleterious effect on FEV1 and FVC with an average follow-up time of 4 months. For patients without COPD, there was a notable improvement in DLCO, which was not
Acknowledgment
The authors thank Dr. Zhigang Xu, Ph.D., and Matthew Worth in the Medical Physics Department for help in data collection of tumor volume.
References (12)
- et al.
Stereotactic single-dose radiotherapy of stage I non-small-cell lung cancer (NSCLC)
Int J Radiat Oncol Biol Phys
(2003) - et al.
Clinical outcomes of a phase I/II study of 48 Gy of stereotactic body radiotherapy in 4 fractions for primary lung cancer using a stereotactic body frame
Int J Radiat Oncol Biol Phys
(2005) - et al.
Results of a phase I dose-escalation study using single-fraction stereotactic radiotherapy for lung tumors
J Thorac Oncol
(2006) - et al.
The North American experience with stereotactic body radiation therapy in non-small cell lung cancer
J Thorac Oncol
(2007) - et al.
Stereotactic body radiotherapy for medically inoperable patients with stage I non-small cell lung cancer: A first report of toxicity related to COPD/CVD in a non-randomized prospective phase II study
Radiother Oncol
(2008) - et al.
Clinical outcomes of stereotactic body radiotherapy for small lung lesions clinically diagnosed as primary lung cancer on radiologic examination
Int J Radiat Oncol Biol Phys
(2009)
Cited by (0)
Conflict of interest: none.