BACKGROUND:Radiotherapy (RT) to the chest or other large areas of the body may cause bone marrow suppression, resulting in anemia and other changes in blood cell counts.

OBJECTIVE:To compare the post­RT hemoglobin levels between patients who underwent forward­ planned intensitymodulated radiotherapy (FPIMRT) and those who underwent three­dimensional conformal radiotherapy (3D­CRT).

DESIGN:Retrospective cohort study

SETTING:Department of Radiological and Imaging Sciences, Southern Philippines Medical Center, Davao City, from October 2018 to March 2019.

PARTICIPANTS:94 women with invasive ductal carcinoma, aged 29 to 75 years, who received at least 28 fractions (with or without boost dose) of either 3D­CRT or FPIMRT.

MAIN OUTCOME MEASURES:Mean hemoglobin counts and anemia within 4 weeks post­RT.

MAIN RESULTS:Of the 94 women, 62 (65.96%) underwent 3D­CRT, and 32 (34.04%) underwent FPIMRT. The proportion of patients with left­sided tumors was significantly higher in the FPIMRT group than in the 3D­CRT group. The baseline hemoglobin levels (12.60 ± 1.04 g/dL for 3D­CRT vs 12.49 ± 0.80 g/dL for FPIMRT; p=0.5994) and the mean changes in hemoglobin count from baseline (­0.11 ± 0.72 g/dL for 3D­CRT vs ­0.18 ± 0.67 g/dL for FPIMRT; p=0.6707) were both comparable between the two groups. The proportions of patients with anemia within four weeks post­RT were also comparable between the two groups (13/62, 20.97% for 3D­CRT vs 8/32, 25.00% for FPIMRT; p=0.6565). Left­sided tumors were significantly associated with post­RT anemia (unadjusted OR 2.87; 95% CI 1.00 to 8.22; p=0.0498), even after controlling for type of RT technique (adjusted OR 3.15; 95% CI 1.01 to 9.87; p=0.0484).

CONCLUSION:After RT, the mean hemoglobin levels of patients with breast cancer who underwent 3D­CRT were comparable with those of patients who underwent IMRT. The type of RT technique was not significantly associated with the occurrence of post­RT anemia in these patients.