Circulating IL-6 as a predictor of radiation pneumonitis.
OBJECTIVE
We report results from a clinical research protocol investigating circulating pro-inflammatory cytokines (interleukin-6 [IL-6] and tumor necrosis factor alpha [TNFalpha]) in relation to radiation pulmonary injury.


METHODS
In a protocol for cytokine measurement, 25 patients had clinical follow-up longer than 12 months, and 24 had serial cytokine data. Serial plasma specimens before, during, and after thoracic radiotherapy were analyzed for IL-6 and TNFalpha using enzyme-linked immunosorbent assay (ELISA). Radiation pulmonary injury was defined using National Cancer Institute Common Toxicity Criteria.


RESULTS
Of the 24 patients, 6 had Grade 1 pneumonitis, and 13 had Grade 2 pneumonitis. There was no Grade 3/4 pneumonitis. Median time of radiation pneumonitis was between 8 and 12 weeks post-therapy. IL-6 levels before, during, and after thoracic radiation therapy were significantly higher in those who developed pneumonitis. In contrast, we did not detect a significant correlation between plasma TNFalpha and radiation pneumonitis.


CONCLUSIONS
High pretreatment plasma levels of IL-6 predisposed patients to the risk of radiation pneumonitis. Pretreatment IL-6 level may serve as a predictor for radiation pneumonitis. Serial plasma IL-6 was consistently higher for the pneumonitis group. The role of IL-6 in the cytokine cascades that promote radiation pulmonary injury deserves further investigation.
Chen
Y
Y
Department of Radiation Oncology, James P. Wilmot Cancer Center, University of Rochester, 601 Elmwood Ave., Box 647, Rochester, NY 14642, USA. ychen@radonc.medinfo.rochester.edu
Rubin
P
P
Williams
J
J
Hernady
E
E
Smudzin
T
T
Okunieff
P
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000097:blood; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D017564:Radiation Pneumonitis / Q000097:blood*; D013899:Thoracic Neoplasms / Q000097:blood / Q000532:radiotherapy*; D014409:Tumor Necrosis Factor-alpha / Q000032:analysis*
D015415:Biomarkers; D015850:Interleukin-6; D014409:Tumor Necrosis Factor-alpha