Comparative Study of the Combination of Trastuzumab with Conventional Radiotherapy versus Trastuzumab with Hypofractionated Radiotherapy in HER2/neu Positive Breast Cancer

Background: Despite the frequent combination of trastuzumab and irradiation
in breast cancer treatment, there is little evidence about the safety of their
concurrent adjuvant administration, particularly with hypo fractionated radiation
therapy (Hypo-RT). We conducted this study to examine the safety of
concurrent administration of Trastuzumab with conventional radiation (Conv-
RT) compared to Trastuzumab with Hypo-RT in Her2/neu breast cancer,
focusing on cardiac and cutaneous toxicities.
Methodology: This prospective randomized open-label study included 150
patients with localized breast cancer who were referred to the medical and
radiation oncology departments at South Egypt Cancer Institute, Assiut
University, from July 2018 to January 2024. Arm A (Conv-RT) included 100
patients, whereas arm B (Hypo-RT) had 50 patients.
Results: There is no significant difference in the reduction of LVEF from
baseline between the groups (p=0.080), with the majority of patients in both
groups showing a reduction of less than 10%. Cardiac toxicity, whether
asymptomatic or symptomatic, is also comparable between the two groups
(p=0.203). Furthermore, all non-cardiac toxicities were acute and only grade I-II
with the exception of lymphedema. There was lower incidence acute skin
toxicity (10% versus 27%), fatigue (2% versus 7%), breast pain (4% versus
10%) with equal percentage of lymphedema cases (2%) in Hypo-RT compared
with conventional RT, respectively.
Conclusion: Hypo-RT administered concurrently with trastuzumab is safe and
feasible with lower incidence of cardiac and skin toxicities compared with
conventional RT in adjuvant breast cancer patients.so, longer follow-up period
is needed to determine long term results.