Background: Complete response has been considered a surrogate for favorable long-term outcome in multiple myeloma. Data on the impact of the duration of response on prognosis are lacking.
Patients and methods: Of the 899 patients enrolled in Total Therapy trials (Total Therapy 1, N = 231; Total Therapy 2, N = 668), 254 survived for > 5 years. The prognostic impact of continuous (Rc) versus discontinuous (Rd) 4-year remission after 5-year survival was examined along with laboratory features present at baseline and at 5 years.
Results: Most baseline prognostic features were evenly distributed among Rc and Rd groups; however, a greater proportion of Rc patients were enrolled in Total Therapy 2 (60%) compared with Rd (19%; P < 0.001). Twelve-year survival (7 years after the 5-year landmark) was 66% with Rc and only 30% with Rd. Hypodiploidy and deletion 13, present in 24 patients at baseline, were associated with a 12-year survival of only 20%. Among the 200 patients lacking these cytogenetic abnormalities, Rc (n = 141) defined a superior 12-year survival rate of 70% versus 35% among those with Rd (n = 59). Initial quality of response (complete response) or having received the scheduled tandem transplantations did not affect post-5-year survival.
Conclusion: Five-year Rc appears to be an important prerequisite for prolonged subsequent overall survival.