Increasing use of post-mastectomy hypofractionated radiation therapy for breast cancer in Victoria

Introduction: The aim of this study was to evaluate the use of post-mastectomy hypofractionationed radiation therapy (HFRT) for breast cancer in Victoria, Australia.

Methods: This is a population-based cohort of women with breast cancer who received post-mastectomy RT to the chest wall with or without nodal irradiation between 2012 and 2017. HFRT was defined as <25 fractions of RT. Data were captured in the Victorian Radiotherapy Minimum Dataset (VRMDS). The changing pattern of HFRT use was evaluated using the Cochran-Armitage test. Patient-, treatment- and institutional-related factors associated with HFRT use were evaluated using multivariable logistic regression.

Results: Two thousand and twenty-one women were included in this study, of which 238 (12%) received HFRT. This increased from 8% in 2012 to 18% in 2017 (P-trend < 0.001). Older women were more likely to have HFRT (26% in women above 70 years vs 6% in women under 50 years; P < 0.001). Women who did not have nodal irradiation were more likely to have HFRT than those who did (18% vs 9% respectively; P < 0.001). In multivariate analyses, the progressive increase in HFRT use over time remained statistically significant - women treated in 2017 were four times more likely to receive HFRT than those treated in 2012 (95% CI = 2.1-7.7; P < 0.001). Other factors independently associated with increased likelihood of HFRT use included increasing age at RT, and lack of nodal irradiation.

Conclusion: In this first Australian study evaluating the use of post-mastectomy HFRT, we observed increasing HFRT use in Victoria over time. We anticipate this rising trend will continue in the coming years.