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Potentially Useful Predictors of Risk for Developing Postradiation Pneumonitis

Potentially Useful Predictors of Risk for Developing Postradiation Pneumonitis

ROCHESTER, New York—Interleukin-6 (IL-6) and interleukin
1-alpha (IL-1a) are potentially useful predictors of risk for development of
postradiation pneumonitis, according to Yuhchyau Chen, MD, PhD.
"Delayed peak of pneumonitis occurs at 6 to 9 months, and we expect
that there will be a role for radioprotective agents in this setting,"
she said. Dr. Chen is assistant professor of radiation oncology, University
of Rochester Medical Center, New York.

"There is significantly increased risk with higher
levels of IL-1a and IL-6, regardless of pneumonitis grade, and suggests a
common mechanism for both asymptomatic (grade 1) and symptomatic (grade 2 or
above) pneumonitis. Circulating IL-1a and IL-6 are potential predictors and
markers for radiation pneumonitis," Dr. Chen said. Preliminary data
also show a delayed peak of TGF-beta at 6 months postradiotherapy.

Adhesion molecules, the selectins, are the cytokines
responsible for lymphocyte adherence to endothelium. "They get cells
out of the vascular system and enable them to home in to the site of
inflammation," Dr. Chen said.

Prospective Protocol

Dr. Chen reported that 75 patients are enrolled in a
prospective translational protocol in which serial blood samples, blood
counts, radiographs, SoMA scoring of respiratory symptoms, and pulmonary
function tests are being used to study radiation pulmonary injury. Over 600
plasma and serum specimens have been collected, plus 250 mRNA extracts from
peripheral lymphocytes. Analysis includes the proinflammatory cytokines
IL-1a, IL-6, and TNF-alpha, the fibrotic cytokines TGF-beta and basic-FGF,
the angiogenic cytokines basic-FGF and vascular endothelial growth factor (VEGF),
the chemokine MCP-1, and adhesion molecules L-selectin, P-selectin, and
E-selectin. Pneumonitis is graded using the National Cancer Institute Common
Toxicity Criteria.

The first set of analysis of 24 patients included 25% with
grade 1 radiographic infiltrates only and 54% with grade 2 symptomatic
pneumonitis. The second set included 59 patients, 40% of whom had grade 2
symptomatic pneumonitis.

Pneumonitis and Fibrosis

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