Abstract: Objective  To observe the longterm effect, adverse reaction and cosmetic outcome of early-stage breast cancer with hypofractionated whole-breast irradiation (HF-WBI) after breast-conserving surgery. Methods  A total of 206 patients with stage 0-Ⅱ breast cancer after breastconserving surgery were included in Shandong Cancer Hospital Affiliated to Shandong University from May 2014 to August 2017. According to radiotherapy fraction, patients were divided into HF-WBI group and conventional wholebreast irradiation (CF-WBI) group. In HF-WBI group, 116 patients received wholebreast radiation to 42.56 Gy in 16 fractions followed by tumor bed boost of 9 Gy in 3 fractions or 10 Gy in 5 fractions. In CF-WBI group, 90 patients received whole breast radiation to 50 Gy in 25 fractions followed by tumor bed boost of 10 Gy in 5 fractions. The 2-year local recurrence rate,  2-year  mortality rate, acute adverse reaction, late adverse reaction and cosmetic outcome of the two groups were analyzed. Results  The 2-year local recurrence rates of HF-WBI group and CF-WBI group were 0.86% (1/116) and 2.22% (2/90) respectively, and there was no significant difference between the two groups (χ2=0.049, P=0.824). The 2year mortality rates of the two groups were 0.86% (1/116) and 0 (0/90) respectively, and there was no significant difference (P>0.999). There were 108 cases (93.1%) in HF-WBI group and 84 cases (93.3%) in CF-WBI group with grade 0-1 acute dermatitis, and 8 cases (6.9%) and 6 cases (6.7%) with grade 2-3 respectively, with no statistically significant difference (χ2=0.004, P=0.948). There were 97 cases (83.6%) in HFWBI group and 79 cases (87.8%) in CFWBI group with grade 01 bone marrow suppression, and 19 cases (16.4%) and 11 cases (12.2%) with grade 2-4 respectively, with no statistically significant difference (χ2=0.704, P=0.401). In the two groups, there were 1 case (0.9%) and 3 cases (3.3%) with grade 1-2 radiation pneumonitis, and 115 cases (99.1%) and 87 cases (96.7%) with no radiation pneumonitis respectively, and the difference was not statistically significant (χ2=1.626, P=0.202). There was 1 case  (0.9%, 1.1%) with grade 1 breast edema in each group, and 115 cases (99.1%) and 89 cases (98.9%) did not occur breast edema, with no statistically significant difference (χ2=0.033, P=0.857). In the late adverse reactions, there were 5 cases (4.3%) and 3 cases (3.3%) with skin pigmentation in HFWBI group and CF-WBI group respectively. There were 2 cases (1.7%, 2.2%) with grade 1 subcutaneous tissue fibrosis in each group, and there were 1 case (0.8%) and 2 cases (2.2%) with grade 1 pulmonary fibrosis respectively. The differences between the two groups were not statistically significant （χ2=0.000, P>0.999； χ2=0.000, P＞0.999； χ2=0.049, P=0.824）. The 6month, 1-year and 2-year cosmetic outcome good rates in HF-WBI and CF-WBI group were 96.5% (111/115) and 93.3% (84/90), 92.1% (105/114) and 90.0% (81/90), 91.4% (53/58) and 87.2% (41/47) respectively. The differences between the two groups were not statistically significant (χ2=0.526, P=0.468;  χ2=0.277, P=0.599;   χ2=0.476, P=0.490). The whole course of radiotherapy time in HF-WBI group was 25 days or 29 days, which was significantly shorter than the 40 days of CF-WBI group. Conclusion  HF-WBI after breastconserving surgery has the similar longterm effect, acute and late adverse reaction and cosmetic outcome compared with CF-WBI, and the treatment time is significantly shorter. It can be further promoted as the optimal adjuvant radiotherapy for earlystage breast cancer after breastconserving surgery.

Key words: Breast neoplasms, Radiotherapy, Treatment outcome