The effect of hemoglobin level on radiotherapy outcomes: the Canadian experience

Studies have shown that hemoglobin (Hb) level is a prognostic factor for outcomes following definitive radiotherapy in patients with a variety of tumors. We conducted a retrospective study on patients with carcinoma of the cervix to evaluate the relationships among Hb level, response to radiation, and effect on local control and survival. Data from 3 years (1989, 1990, 1992) were collected at seven institutions across Canada from women who received definitive radiotherapy, > or = 3,500 cGy, for carcinoma of the uterine cervix. The collected data included Hb levels at presentation and during radiation treatment specific for the time course of anemia and blood transfusion practice, patient demographics, details of the treatment regimen, and outcomes. Of 630 patients reviewed, 605 were eligible and were included in the analyses; median follow-up was 41 months. Twenty-five percent of patients received blood transfusions, most frequently when Hb decreased to below 100 g/L. Baseline Hb > or = 120 g/L was shown on univariate analysis to be significant for higher rates of pelvic disease control and disease-free survival. On multivariate analysis, baseline Hb was not a significant prognostic factor, but average weekly nadir Hb (AWNH) levels during radiotherapy were shown to be significant, and second only in importance to tumor stage. Five-year survival rates were similar if AWNH levels were > or = 12 g/L, regardless of whether baseline Hb was lower than 120 g/L (70%) or > or = 120 g/L (74%); the difference in 5-year survival between patients with lower AWNH (< 120 g/L) and higher AWNH (> or = 120 g/L) was significant. Patients with higher AWNH had significantly lower rates of overall relapse, local recurrence, and distant metastases. A stepwise significant increase was noted in overall survival rate as AWNH levels increased, regardless of transfusion status. Hemoglobin levels > or = 120 g/L during radiotherapy were shown to be a significant prognostic factor for successful radiotherapy and disease-free survival. There was no difference in outcomes relative to transfusion status.