Purpose: To determine the significance of eosinophilia and serum interleukin 5 (IL-5) levels induced by radiotherapy in patients with gynecological cancer.
Materials and methods: First, we examined changes in the number of eosinophils before and during radiotherapy in 145 patients with cervical cancer who underwent external radiotherapy and brachytherapy. Eosinophilia was defined as > or =10% eosinophils or > or =500 eosinophils/mm3. Next, we determined serum IL-5 levels prospectively in 20 patients, comprising 18 cases of cervical cancer, one of uterine corpus cancer, and one of vaginal cancer.
Results: Eosinophilia was seen in 88 patients (61%). Patients with advanced disease stage IV showed 32% eosinophila, lower than those of stage I (63%), II (69%), and III (65%) disease patients (p=0.03). The 5-year cause-specific survival rate was 76% for patients with eosinophilia (+) and 53% for patients without eosinophilia (p=0.0003). Thus, eosinophilia correlates to stage classification and a good prognosis. Of the 20 patients studied prospectively, the six with elevated serum IL-5 level at one week (6/20=30%) all showed eosinophilia (100%), whereas only six of the other 14 patients had eosinophilia (43%, p=0.04).
Conclusion: Radiotherapy induced transient elevation of serum IL-5 levels and is related with eosinophilia, which is correlated to prognosis.