Patient characteristics
We retrospectively analyzed data from a total of 181 patients in this study, 164 patients of these underwent treatment with four to eight courses of continuous induction chemotherapy. The median observation time was 48.4months (range of 9~114 months). The distribution of baseline characteristics for 164 MM patients diagnosed for the first time based on the reduction rate of M protein after first and fourth cycle chemotherapy are presented in Table 1. The results showed no significant differences in gender, Durie–Salmon (DS) stage, glutamic-pyruvic transaminase (GPT), glutamic-oxaloacetic transaminase (GOT), catabolite activator protein (CRP), albumin/globulin, lactate dehydrogenase (LDH), t(6;14), t(11;14), t(14;16), maintenance regimen, total cholesterol (TC), triglyceride (TG), phosphorous (P) concentrate between the groups of reduction rate of M protein after first chemotherapy of ≥50% versus vs <50% and the reduction rate of M protein after fourth chemotherapy ≥75% vs <75% (Table 1).
Higher reduction rate of M protein after first cycle and fourth cycle chemotherapy act as adverse prognostic factors for progression-free survival of multiple myeloma during initial diagnosis
The parameters such as age (PFS: P=0.000; OS: P=0.002), ISS stage (PFS: P=0.001; OS: P=0.000), DS stage (PFS: P=0.028; OS: P=0.045), GOT (PFS: P=0.000; OS: P=0.000), LDH (PFS: P=0.000; OS: P=0.000), UA (PFS: P=0.000; OS: P=0.000), del(17p) (PFS: P=0.000), t(14;16) (PFS: P=0.000; OS: P=0.028), t(14;20) (PFS: P=0.002; OS: P=0.028), t(4;14) (PFS: P=0.000; OS: P=0.000), platelet count (PFS: P=0.000; OS: P=0.000), autotransplantation (PFS: P=0.020; OS: P=0.022), TC (PFS: P=0.013; OS: P=0.007) , C1 reduction rate (PFS: P=0.000; OS: P=0.000), C2 reduction rate (PFS: P=0.000; OS: P=0.000), C3 reduction rate (PFS: P=0.000; OS: P=0.000), and C4 reduction rate (PFS: P=0.000; OS: P=0.000) were significantly associated with PFS and OS. Maintenance regimen (P=0.038), and GPT (P=0.019) were related to PFS (Table 2). When entered into a Cox regression model for multivariate analysis, age (HR: 1.059, 95% confidence Interval: 1.033-1.085, P=0.000), ISS stage (HR: 2.136, 95% confidence Interval: 1.500-3.041, P=0.000), del(17p) (HR: 20.598, 95% confidence Interval: 3.570-118.848, P=0.001), t(14;16) (HR:3.914, 95% confidence Interval: 1.180-12.978, P=0.019), t(14;20) (HE: 13.988, 95% confidence Interval: 2.438-80.385, P=0.019), t(4;14) (HR: 1.414, 95% confidence Interval: 0.562-3.558, P=0.019), autotransplantion (HR: 0.201, 95% confidence Interval: 0.069-0.583, P=0.019), TC (HR: 0.689, 95% confidence Interval: 0.533-0.891, P=0.019), C1 reduction rate (HR: 0474, 95% confidence Interval: 0.293-0.767, P=0.019), and C4 reduction rate (HR: 0.254, 95% confidence Interval: 0.139-0.463, P=0.019) were considered as predictors of PFS (Table 3). Age (HR: 1.054, 95% confidence Interval: 1.027-1.081, P=0.024), ISS stage (HR: 1.879, 95% confidence Interval: 1.315-2.686, P=0.001), del(17p) (HR: 6.527, 95% confidence Interval: 1.095-38.893, P=0.039), t(14;16) (HR: 4.874, 95% confidence Interval: 1.344-17.684, P=0.016), t(14;20) (HR: 30.719, 95% confidence Interval: 4.811-196.154, P=0.000), t(4;14) (HR: 4.478, 95% confidence Interval: 1.814-11.061, P=0.001), platelet count (HR: 2.929, 95% confidence Interval: 1.269-6.756, P=0.012), autotransplantion (HR: 0.211, 95% confidence Interval: 0.069-0.647, P=0.006), and TC (HR: 0.735, 95% confidence Interval: 0.573-0.943, P=0.016) act as dependent predictors for OS (Table 4).
The reduction rate of M protein after first cycle chemotherapy affects PFS
PFS was analyzed by using the reduction rate of M protein after first cycle chemotherapy. The patients were divided into two groups, patients with reduction rate of M protein of ≥25% and patients with <25%. The results revealed that the 36 months PFS rate showed no significant difference between the two groups (P=0.319). Then the reduction rate of M protein ≥50 vs <50% was compared. The 36 months PFS rate of the reduction rate of M protein ≥50% after first cycle chemotherapy was significantly higher than the reduction rate <50%, in which one was 44.3% and another was 8.1% (P<0.001). The K–M curve and the log-rank tests revealed significant differences between the two groups (P<0.001), (Figure 1).
The reduction rate of M protein after fourth cycle chemotherapy affects PFS
Comparison of PFS on the reduction rate of M protein after fourth cycle chemotherapy ≥25% vs <25%, ≥50% vs <50% and ≥75% vs <75%, and the results revealed that 36 months PFS rate showed no differences between ≥25% vs <25% groups (P=0.248) and ≥50% vs <50% groups (P=0.228). But significant differences were observed between ≥75% vs <75% group. The PFS rate of reduction rate at 36 months ≥75% was 36.9% and was 5.0% in reduction rate <75% (P<0.001). The K–M curve and the log-rank tests revealed that the reduction rate of M protein after fourth cycle chemotherapy in ≥75% PFS was longer than that in <75% (P<0.001), (Figure 2).