Prognostic model based on regression tree analysis
| Category/age, y . | No. (%) . | Complete response, no. (%) . | CR duration . | Overall survival . | ||
|---|---|---|---|---|---|---|
| Median, mo . | 6-y prog free, % . | Median, mo . | 6-y surv, % . | |||
| β2-microglobulin less than 2N, any age | 168 (57) | 141 (84) | 86 | 72 | Not reached | 85 |
| β2-microglobulin 2N or more | ||||||
| Less than 70 y | 96 (33) | 58 (60) | 81 | 66 | Not reached | 72 |
| 70 y and older | 31 (11) | 15 (48) | 85 | 72 | 48 | 48 |
| Category/age, y . | No. (%) . | Complete response, no. (%) . | CR duration . | Overall survival . | ||
|---|---|---|---|---|---|---|
| Median, mo . | 6-y prog free, % . | Median, mo . | 6-y surv, % . | |||
| β2-microglobulin less than 2N, any age | 168 (57) | 141 (84) | 86 | 72 | Not reached | 85 |
| β2-microglobulin 2N or more | ||||||
| Less than 70 y | 96 (33) | 58 (60) | 81 | 66 | Not reached | 72 |
| 70 y and older | 31 (11) | 15 (48) | 85 | 72 | 48 | 48 |
Patients with β2-microglobulin (β2m) less than twice upper limit of reference (< 2N) had a favorable 6-year survival of 85%, with no significant difference and between younger (< 70 years, n = 158) and older (≥ 70 years, n = 10) patients (6-year survival 84% vs 90%, respectively, P = .73). Patients with β2m 2N or more and age younger than 70 years had intermediate survival (6-year survival 72%, P = .003 compared with low β2m patients), and those with β2m 2N or more and age 70 years or older had the most unfavorable survival (6-year survival 48%, P = .007 compared with intermediate risk patients). For those patients who achieved complete remission, remission duration was similar regardless of pretreatment risk category.