Incidence and reasons for discontinuation of first-line therapy in patients with multiple myeloma: results from a historical cohort, Brazil 2009-2020.

Multiple myeloma (MM) is an incurable hematological cancer requiring multiple lines of anti-myeloma regimens to promote disease remission and increase patient survival. The study assessed the incidence and reasons for discontinuation of first-line therapy in outpatients who started MM therapy in Belo Horizonte, Brazil from 2009 to 2020. A historical cohort study in which patients were followed from treatment initiation until discontinuation of first-line therapy. Discontinuation of first-line therapy was characterized as (i) discontinuation followed by a second-line therapy, and (ii) discontinuation that prevented patients from receiving a subsequent line of treatment. Non-parametric competing risk analysis with a 95% confidence interval estimated the cumulative incidences of discontinuation followed by a second-line therapy. The probability of discontinuation was compared according to selected variables using the Gray's test at a significance level of 5%. Approximately half of the participants (n = 260) were female and younger than 65 years. Discontinuation of first-line therapy followed by a second-line therapy accounted for 50.4% of the patients and occurred up to 30th month. The main reason for discontinuation not qualifying patients for receiving second-line therapy was to achieve a response to treatment. The maximum times for discontinuation not followed by a second-line therapy ranged from 12 to 20 months due to deaths or response to treatment. The probability of receiving second-line therapy was higher among patients initiating therapy in 2009-2014 and those not undergoing transplantation. In conclusion, discontinuation of first-line therapy followed by second-line treatment occurred as likely as the discontinuation not followed by a subsequent line.