OBJECTIVEThe purpose of this study was to investigate whether the associated diabetes mellitus exerts a certain effect on the development of radiation pneumonitis in patients with non-small cell lung cancer.

METHODS156 patients with non small cell lung cancer were treated with three-dimensional conformal radiation therapy in this study, including 52 associated with diabetes and 104 non-diabetic patients as a control group. All the patients were followed up for one year and the development of radiation pneumonitis was observed. Radiation pneumonitis was diagnosed according to the criteria of radiation therapy oncology group. The morbidities of radiation pneumonitis in the two groups were compared. The relationships between the morbidity of radiation pneumonitis and blood sugar level as well as diabetic history were analyzed by chi-square test.

RESULTSTwenty-one (40.4%) of 52 patients with diabetes had radiation pneumonitis (grade 2 or greater), while in the control group only 22 of 104 patients (21.2%) suffered from radiation pneumonitis. There was a statistically significant difference between the two groups in the morbidity of the radiation pneumonitis (P < 0.05), with a relative risk value of 2.05 (95% CI, 1.17, 3.58). The rate of the radiation pneumonitis in the patients with a lower blood sugar level (< 7 mmol/L) was significantly lower than that in those with a higher blood sugar level (30.6% vs. 62.5%, P < 0.05). However, the rate of radiation pneumonitis in the patients with a longer diabetic history was not significantly different from that in those with a shorter diabetic history (P > 0.05).

CONCLUSIONNon-small cell lung cancer patients with diabetes mellitus are more vulnerable than those without to radiation pneumonitis. Therefore, diabetes mellitus is a newly discovered risk factor to radiation pneumonitis, and the blood sugar level is positively correlated with the morbidity of radiation pneumonitis.