3.1 Patient characteristics
The clinical characteristics of the investigated group are presented inTABLE 1 . We reviewed a total of 374 pediatric patients with the four NHL subtypes; the median age was 9 years (range, 1–18 years). There were 283 male (75.7%) and 91 female patients (24.3%). The majority of patients were diagnosed as BL (n = 180; 48.1%) and LBL (n = 95; 25.4%); the remaining patients were diagnosed as ALCL (n = 64; 17.1%) and DLBCL (n = 35; 9.4%). There were 327 patients (87.4%) at an advanced stage (stage III/IV) at diagnosis; 159 (42.5%) and 152 patients (40.6%) were stratified into the intermediate- and high-risk group, respectively. At diagnosis, the incidence rate of bone marrow (BM) and central nervous system (CNS) involvement was 18.7% (70 cases) and 9.6% (36 cases), respectively. After BFM 95 chemotherapy, 322 (86.1%) and 9 patients (2.4%) achieved CR and SD, respectively. Twenty-one patients (5.6%) died. Treatment response evaluation was not available in 14 patients (3.7%) due to discontinuation of therapy. Of these, eight (2.1%) were still under treatment at the time of the last follow-up. The median follow-up time was 28.5 months (range, 1–76 months) for all patients. The estimated 5-year EFS and OS were 74.2% and 85.7%, respectively. In total, events were recorded for 82 patients (21.9%), including PD (n = 29; 7.6%), relapse (n = 31; 8.3%), secondary malignancy or LCH (n = 4; 1.1%), and death (n = 42; 11.2%). Some patients had >1 type of event. Among the four cases with secondary malignancy or LCH, one female patient with BL and one male patient with B cell-LBL (B-LBL) (CNS-positive) were diagnosed as secondary acute myeloid leukemia (AML-M5) 2 months and 36 months after achieving CR, respectively. They both then died of cancer. One male patient with DLBCL was diagnosed as B cell ALL (B-ALL) (Ph+), and another male patient with T cell LBL (T-LBL) was diagnosed as LCH 15 months and 26 months after achieving CR, respectively. They were both alive and were under chemotherapy at the last follow-up date.