Results:
A total of 115 patients, 70 male and 45 females (male/female: 1.56), were included in the study. The median follow-up period was 70 months. The gender and age characteristics, the mean initial laboratory values, and blast cell phenotypes of the patients according to risk groups are summarized in Table3.
One hundred three (89.6%) children had a pre–B-cell phenotype, 12 (10.4%) had a T-cell phenotype. According to the Total Therapy XV risk stratification criteria, 32 (27.8%) children were classified as low risk (LR), 63 (54.8%) as standard risk (SR), and 20 (17.4%) as high risk (HR).
Treatment Results
All 112 (97.4%) of the patients who completed remission induction therapy and whose BM could have been investigated at the remission date were in remission. Three (2.6%) children died in the induction period before the remission date.
Considering all patients, at a mean follow-up of 68 months (range, 1 to 115 mo), 5-year OS was 80%, (mean follow-up time 94.5 months, 95% CI 86.5-102), and EFS was 78.3% (mean 93.3 months, 95% CI 85.7-100.1).
Evaluation of survival according to gender showed that 5-year OS was 84.3% in boys and 73.3% in girls (98.7 months, 95% CI: 89.8-107.6 and 87, 95% CI: 73.9-100.2) 5-year OS rates were 78.1, 81%, and, 80% for the LR, SR, and HR groups, respectively. 5-year EFS rates were 75.9%, 79.4%, and 78.3% for the LR, SR, and HR groups, respectively. There was no significant difference between the groups according to the risk stratification (p=0.95). In the evaluation of survival according to the cellular origin, survival was 80.6% in the B-cell group (n=103) 95.1 (95% CI 87.3-103), and 75% in the T-cell group (n= 12) (70.8 months, 95% CI 50-91.6) OS was 82.1% in the group with baseline WBC <50,000 cells/mm3 while it was 70% in the group>50,000 cells/mm3 (n=20). However, there was no statistically significant difference due to the small number of patients (p=0.1). When we took the threshold value of 100,000 cells/mm3 for the initial WBC value, the difference became more evident. We observed OS was 82.4% in the WBC <100,000 group (n=102) vs 61.5% in WBC≥100,000 cell/mm3 group (n=13) (p=0.56).
When the results were evaluated according to the age of onset, OS was 82.7% in the 1-9.99 age group (n=98) and was 64.7% in the group over ten years old (n=17). (p=0.07) We attribute the statistical insignificance of these rates to the low number of patients in the second (>10 age) group. But when we look at the EFS rates, we see a statistically significant difference in patients over 10 years old. The EFS was 81.6% in the 1-9.99 age group (n=98) and was 58.8% in the group over ten years old (n=17). (p=0.035)
Of the eight patients whose cytogenetic features could not be determined, four died. Although small in number (n=4), all patients with t (1;19) TCF3-PBX1 mutation survived, while all patients with hypodiploid (n=3) karyotyping died.
Three (2.6%) of patients had bone marrow relapses. (pre-B or T cell) All of these patients had been treated with relapse ALL protocols, and one of them had no response to treatment and died due to progressive disease. In the other two patients, remission was achieved with the relapse protocol, and then stem cell transplantation was performed. These two patients were still alive for 20 and 48 months after relapsing. Only one patient (0.87%) developed an isolated CNS relapse, and he was cured with a bone marrow transplantation from his brother after relapse chemotherapy treatment. Ten of our patients underwent SCT. Four of them were due to MRD positivity detected on the 46th day.
When the causes of death of our patients were examined, it was seen that 19 of the 23 patients died due to infection and infection-related complications [three patients (2.61%)] died in the induction phase, and 16 (13.91%) died due to infectious cause while in remission), two patients died due to progressive, disease, and two patients died due to HSCT complications.