ABSTRACT OBJETIVE To evaluate the effect of ribociclib versus endocrine therapy on productivity losses due to advanced breast cancer. METHODS Productivity data from the MONALEESA-7 trial, obtained from the results of the application of the Work Productivity and Activity Impairment (WPAI) questionnaire on progression-free survival state (43-month follow-up), were extrapolated to the 10,936 Brazilian prevalent cases of premenopausal women with hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) breast cancer. Productivity loss was determined by quantifying the economic costs of workforce dropout over time in both treatment arms and by discounting the economic costs of absenteeism and presenteeism from workforce retention. A human capital approach was used. RESULTS Net productivity gains in the ribociclib arm were estimated at USD 4,285,525.00, representing 316,609 added work hours over 43 months and a mean of 2,009 added work weeks per year. CONCLUSIONS The phase III MONALEESA-7 trial productivity results applied to the Brazilian premenopausal prevalent cases of hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) breast cancer showed that treatment with ribociclib + endocrine therapy improves workforce participation compared with endocrine therapy alone in premenopausal women with hormone receptor positive/human epidermal growth factor receptor 2 negative (HR+/HER2-) metastatic breast cancer, with potential economic gains for the Brazilian society.