Comparison of adverse events between intensity-modulated radiation therapy and Tomotherapy for early-stage breast cancer: a retrospective cohort study

Introduction : Early-stage breast cancer treated with adjuvant radiotherapy with two different techniques, Tomotherapy (TOMO) and intensity-modulated radiation therapy (IMRT) and their acute adverse events in terms of skin toxicity, localized edema, sore throat, tracheal mucositis, nausea, mucositis oral, esophagitis and pneumonitis outcomes are compared. Material/methods : A retrospective cohort study was conducted on adverse events comparing IMRT and TOMO in early-stage breast cancer, we reviewed the data of female patients who received lumpectomy or mastectomy for breast cancer in the Oncology Department of the First Affiliated Hospital, Army Medical University from September 2021 to February 2024. A total of 315 female patients were enrolled in this study, including 130 in the TOMO group and 185 in the IMRT group. In this study, the adverse events of the two groups of patients were compared and analyzed. Results : The median age of this retrospective cohort was 47 years (range, 20–74 years). The length of follow-up was 3 months. 185 patients (59%) received IMRT and 130 patients (41%) underwent TOMO. No significant difference was observed in terms of menopausal status, laterality, pathology, estrogen receptor status, progesterone receptor status, triple negative, clinical T stage, clinical N stage or Surgical methods. Negative HER-2 over-expression was found in 38% and 51% of TOMO and IMRT group respectively (P = 0.053).With regard to the the degree of tumor differentiation,the Poor-Moderate differentiation was 69% in TOMO group while 81% in IMRT group(P = 0.052).There was 66% and 55% of TOMO and IMRT group respectively receiving Hormone therapy(p = 0.5). But there is no statistical differences in demographic and tumor characteristics between TOMO group and IMRT group. The comparison adverse events between TOMO and IMRT shown that there were no significant differences in localized edema, sore throat, tracheal mucositis, nausea, mucositis oral, esophagitis between the TOMO and the IMRT groups. Compared these two groups, the TOMO group had a higher proportion of 3–4 grade skin toxicity [16.2% (TOMO) versus 7.6% (IMRT), P = 0.017]. The pneumonitis in the TOMO group was lower than the IMRT group [0.0% (TOMO) versus 4.3% (IMRT), P = 0.016]. Conclusions : Compared to IMRT, TOMO decreases the incidence of radiation Pneumonitis but fail to improve acute skin toxicity. Base on our research, TOMO may contribute to higher odds for acute skin toxicity, which should be payed more attention by clinicians.