Long-term changes in pulmonary function tests after definitive radiotherapy for lung cancer

Keith L. Miller, Su Min Zhou, Robert C. Barrier, Timothy Shafman, Rodney J. Folz, Robert W. Clough, Lawrence B. Marks

Research output: Contribution to journalArticle

50 Scopus citations

Abstract

Purpose: To evaluate the long-term changes in pulmonary function tests (PFTs) in patients surviving at least 2 years after definitive radiotherapy (RT) for unresectable lung cancer. Methods and Materials: Between 1992 and 2000, 277 patients were enrolled in a prospective clinical study to relate RT-induced changes in lung function with dosimetric and functional metrics. Of these, 128 received definitive RT for lung cancer, and 13 of these had follow-up PFTs for approximately ≥2 years without evidence of recurrent or progressive cancer. PFTs were obtained before RT and approximately every 6 months after RT. The results were evaluated on the basis of each study's "percentage of predicted" of normal values (i.e., adjusted for age, gender, height), and a patient's sequential examinations were compared with their initial study and a percentage of the baseline value was calculated. Follow-up PFTs were available for a median of 38 months (range 23-95). The median patient age was 65 years (range 40-74), 6 patients were men, and 10 were white. Most had Stage T2-T4 and N2-N3. The median RT dose was 71.4 Gy (range 60-73), 6 had twice-daily RT. Four patients received chemotherapy, one concurrent and three neoadjuvant. None of the patients continued to smoke after their treatment. The median pre-RT PFT results were (percentage of predicted) forced expiratory volume in 1 s, 67% (range 24-121); forced vital capacity, 72% (range 45-116); and diffusing capacity of lung for carbon monoxide, 70% (range 41-129). Results: At 6 months, all PFT values had declined, with some stabilization by 1 year. However, after 1 year, a gradual reduction occurred in all three parameters. Ten patients (77%) developed RT-induced respiratory symptoms (2 cough only, 8 dyspnea) at 2-21 months (median 5) after treatment. Two patients required inhalers, another required long-term steroids and oxygen. Of the 8 patients with dyspnea, 7 had an increase in symptoms beyond 2 years. No patient died of RT-induced pulmonary insufficiency. Conclusion: RT caused a decline in PFTs that was apparent at 6 months and continued well beyond 1 year. The continued decline in PFTs is suggestive of progressive/evolving RT-induced lung injury. "Late" pulmonary symptoms have also occurred in these patients. Because of the high mortality rate of unresectable lung cancer, few patients can be evaluated for long-term analysis. Additional studies and pooling of data from multiple institutions may help to clarify better the long-term impact of RT on pulmonary function in this subset of patients.

Original languageEnglish (US)
Pages (from-to)611-615
Number of pages5
JournalInternational Journal of Radiation Oncology Biology Physics
Volume56
Issue number3
DOIs
StatePublished - Jul 1 2003
Externally publishedYes

Keywords

  • Lung cancer
  • Pulmonary function tests
  • Radiotherapy

ASJC Scopus subject areas

  • Radiation
  • Oncology
  • Radiology Nuclear Medicine and imaging
  • Cancer Research

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