Circulating Humoral Factors and Lymphocyte Subsets as Markers for Radiation Pulmonary Injury
Theodore Robnett, MD
OncoLink Assistant Editor
Last Modified: November 1, 1999
Presenter: Yuhchyau Chen, M.D. Affiliation: University of Rochester
Summary: Radiation induced pulmonary changes can cause serious, even life-threatening problems in patients whose lung function my already be compromised by tumor burden and/or smoking. Humoral factors and immune cells have been previously associated with the presence of radiation-induced pulmonary injury.
Methods: The authors prospectively monitored multiple factors, including IL-1a, IL-6, TNF-a, TGF-b1, bFGF, vascular endothelial growth factor (VEGF), and multiple adhesion molecules, prior to, during, and post-treatment. Treatment consisted of thoracic radiation therapy with or without chemotherapy. Radiation pneumonitis was scored using clinical symptoms and radiographic changes on chest X-ray and computerized tomography scans.
Of 38 evaluable patients, 27 were found to have some degree of pneumonitis at 3 to 4 months post-treatment,
14 of 38 patients experienced symptomatic pneumonitis requiring steroids.
IL-1a and IL-6 were found to be significantly higher before, during, and after treatment in patients with pneumonitis (p < 0.05). In particular, patients with elevated serum IL-6 prior to treatment were more likely to develop symptomatic radiation pneumonitis.
TGF-b1, bFGF, the selectins, MCP1, VEGF followed regular patterns during and after treatment, but were not correlated with radiation pneumonitis.
CD4+, CD8+, and CD19+ lymphocytes were monitored during treatment in 16 patients. CD4+ count declined in all patients receiving thoracic RT, but recovery was lower for patients with symptomatic radiation pneumonitis than without (p < 0.05).
These data contribute to the pre-existing information suggesting the association of humoral factors and immune cells with radiation lung injury. As such, they may be a valuable adjunct in selecting and monitoring patients at risk for symptomatic pneumonitis.
The exact role played by each of these factors in radiation lung injury, whether reactive or causal, requires further investigation.
The contribution of chemotherapy to toxicity deserves attention, as does the relatively high rate of symptomatic pneumonitis in this study group.