Updating survival estimates in patients with chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL) based on treatment-free interval length.

We hypothesized that the length of treatment-free survival following (a) initial diagnosis and (b) first-line treatment would be associated with improved subsequent five-year relative survival (RS5) in patients with chronic lymphocytic leukemia or small lymphocytic lymphoma (CLL/SLL). 19,879 patients incident CLL/SLL cases (median age = 76 years) were identified from SEER-Medicare. RS5 improved from 0.73 (95% CI: 0.72, 0.74) at diagnosis to 0.81 (95% CI: 0.80, 0.82) at year 1 and 0.89 (95% CI: 0.83, 0.96) at year 10 among those who had not received treatment. In our analysis of survival patterns following first-line treatment, RS5 improved from 0.55 (95% CI: 0.53, 0.57) at initiation of first-line treatment to 0.84 (95% CI: 0.75, 0.92) among patients who had not been retreated at year 5 following first-line therapy. Longer periods of treatment-free survival following initial diagnosis and first-line treatment were both predictive of meaningfully improved prognosis in CLL/SLL patients.