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The aim of the paper is to present the initial results of molecular examination which was started in 2006 for children with acute myeloid leukemia. Better knowledge of biology of this disease, can result in establishing of new risk factors what allows more precise patient stratification to different therapeutic groups. Study was obtained patients until to 18 years of age treated according to AML-BFM 2004 INTERIM protocol in 14 centers of the Polish Pediatric Leukemia/Lymphoma Study Group. Mononuclear cells were collected from bone marrow on time points established according to the AML-BFM 2004 INTERIM protocol. Collected cells were isolated on Ficoll gradient, and RNA and DNA were isolated using TRIZOL reagent. To synthesize cDNA an amount of 1 mg of total RNA was used. To perform quantitative RT-PCR and RQ-PCR reactions 4 fusion gene transcripts (AML1-ETO, CBFb-MYH11, PML-RARA /subtype bcrl and bcr3/) were used according to the protocol established by Europe Against Cancer Program. An expression of WT1 gene was tested additionally. An analysis of ABL control gene was used to normalize of achieved results. Determination of duplication of FLT3 gene in DNA sample was performed with starters complementary to JM region. Genotyping was performed in 75 patients with acute myeloid leukemia so far. AML1-ETO fusion gene transcript was found in 14 patients (19%). PML-RARA (subtype bcr3) and CBFB-MYH11 gene transcripts were detected in 3 (4%) and 3 (4%) patients, respectively. Duplication of FLT3 gene was found in 4 (5.3%) cases. Between 67 tested children over expression of WT1 was present in 51 patients (76%). Analysis of MRD level in subsequent time points showed systematic decrease of number of fusion gene transcript copies and gene WT1 expression. To establish the rate of molecular marker presence in AML in children and the influence of the presence of MRD on the treatment results as well, the study has to be conducted on a larger group of patients with longer follow-up.

Over the last few years, treatment failures (progression, relapse) in Hodgkin's disease (HD) occurred mainly in elder children treated in the Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG) participating centers. That is why analysis of the influence of age on the treatment outcome in children and adolescents treated with the protocol introduced in 1997 was performed. In years 1997-2001, in 10 centers of PPLLSG, 280 patients (age 2.3-18.8 years) were treated for HD. In all patients MVPP and B-DOPA chemotherapy with or without radiotherapy was introduced. Among 280 treated children the first remission was achieved in 275 patients (98.2%). Relapses occurred in 11 patients (4%). The 5-year probability of overall survival, relapse-free survival (RFS) and event-free survival (EFS) was 99%, 93% and 90%, respectively. All children with relapse were over 10 years old at the time of diagnosis (range: 10.6-17.1, median 14.6 years); mediastinal tumor mass was present in all of them. The logistic regression analysis did not reveal the border value for increasing the probability of relapse or event, thus age of 10 years (age of the youngest child with relapse) was identified as the border value. The probability of 5-year EFS and RFS for children over and under the 10th year of age was 98%, 92% and 100%, 92%, respectively. The differences were not statistically significant. Among children over the 10th year of age some features of the disease occurred more frequently: female sex, shorter history of the disease, presence of mediastinal tumor, greater stage of the disease, NS histopathological type of the disease, presence of general signs and ESR over 50 mm, greater tumor burden and higher number of involved lymphatic regions. Among the patients over the 10th year of age, the presence of the general signs and mediastinal tumor influenced the occurrence of relapses substantially. The aim of the further treatment modifications ought to comprise the need of better treatment outcome, especially in patients over the 10th years of age in which unfavorable prognostic factors are identified. child with relapse) was identified as the border value. The probability of 5-year EFS and RFS for children over and under the 10th year of age was 98%, 92% and 100%, 92%, respectively. The differences were not statistically significant. Among children over the 10th year of age some features of the disease occurred more frequently: female sex, shorter history of the disease, presence of mediastinal tumor, greater stage of the disease, NS histopathological type of the disease, presence of general signs and ESR over 50 mm, greater tumor burden and higher number of involved lymphatic regions. Among the patients over the 10th year of age, the presence of the general signs and mediastinal tumor influenced the occurrence of relapses substantially. The aim of the further treatment modifications ought to comprise the need of better treatment outcome, especially in patients over the 10th years of age in which unfavorable prognostic factors are identified.

Clear statement that pediatric neoplasms are really rare is not easy. Thus the incidence of rare tumours in children has not been defined so far. The paper efforts to assess the topic of rare tumours of childhood in the Polish population. Following two categories are proposed: tumours typical for adults, but possible in children (neoplasms of epithelial origin--mainly carcinomas, melanomas, carcinoids) and paediatric tumours consisting less than 10% of cases in corresponding clinical groups according to the ICCC classification. Data on 317 patients aged 0-18 years treated in centres associated in the Polish Paediatric Group for Solid Tumours (PPGST) were analysed. Classical adult malignancies were registered in 130 patients: carcinomas in 90 (mean age 12.6 +/- 4.5 years), melanomas in 25 (mean age 9.4 +/- 4.9) and carcinoids in 9 (mean age 14.5 +/- 1.2 years). Non epithelial neoplasms were registered in 187 patients (mean age 10.4 +/- 5.5). That group included rare tumours of soft tissue, CNS, bones and other organs. Treatments of certain groups were specified by separate therapeutic protocols within PPGST. Rare malignancies of adult-type among children under 18 years of age in Poland comprised 1.5% of all pediatric neoplasms. The incidence of adult-type neoplasms increased with age until 14 years. In patients over 15 years of age the number of registered cases decreased. It may suggest a first peak of incidence in early adolescence or an underestimation of number of patients with carcinoma aged over 15 years. In the analyzed group, the mean age of patients with carcinomas and other epithelial and unspecified tumours significantly exceeded the age of children with rare neoplasms of non-epithelial origin (12.1 +/- 4.7 vs 10.4 +/- 5.5 years; p0.05). A very young age at diagnosis of malignant melanomas (mean 9.4 years) and numerous cases of carcinomas affecting the digestive tract (n=24; 27% of all carcinomas), especially those located in colorectal region (n=10), seem surprising. The preliminary analysis of the collected data on rare neoplasms in Poland encourage to undertake a prospective study, meant to link the epidemiology and characteristics of rare epithelial tumours in childhood with diagnostic and therapeutic suggestions for these types that are not coordinated within Polish Paediatric Group of Solid Tumours.

Prognostic significance of residual mediastinal tumor mass in children treated for HD as well as the choice of the optimal management of these cases still remains unknown. In years 1994-2001 in 10 PPLLSG participating centers 480 children (age 2-19.7 years) were treated for HD (stages I-IV). In 338 cases initial mediastinal/lung hilus involvement was present. All patients with initial mediastinal/lung hilus involvement were treated with multidrug chemotherapy combined with involved field radiotherapy. In five cases remission was not achieved. Complete remission (CR) was achieved in 226 patients and uncertain complete remission (UCR) in 107 patients, in whom after completion of planned treatment residual changes in mediastinum/lung hilus were identified in radiological examinations. Twenty four children with persistent mediastinal tumor underwent thoracoscopy or thoracotomy. In only one case histopathological examination revealed the presence of neoplastic cells in mediastinal mass tissue, in 2 another cases cystic changes in mediastinum were present, in one case thymic tissue was identified, necrotic tissue was present in 20 cases. Among 107 children with residual mediastinal tumor and 226 patients with CR achieved, relapses occurred in 6 and 18 patients respectively. Over 5-year relapse-free survival was 92.4% and 91.3% respectively. Patients with the presence of mediastinal/lung hilus tumor after the completion of the treatment do not have an increased risk of relapse, but before the completion of therapy they require careful, clear-sighted and repeated examinations including computed tomography (CT), magnetic resonance imaging (MRI) and especially positron emission tomography (PET) to evaluate the nature of persistent lesions. Only in clinically and radiologically doubtful cases tumor biopsy with subsequent histopatological examination should be performed.

Currently over 90% of children with HD can be cured thanks to use of chemotherapy (CT) combined with involved field radiotherapy (IF-RT). From 1971 to 2001, 1062 children and adolescents with HD (stage I to IV) were treated in 10 oncological centers PPLLSG. Majority of patients were treated with CT combined with IF-RT. Year by year the intensity of therapy (CT and RT) was gradually adjusted to the risk-factor groups, and invasive methods of staging were also gradually limited. Supportive care was improved at the same time. Along with the modified therapy protocol, five consecutive periods of time (I: 1971-82; II: 1983-87; IIII: 1988-93; IV: 1994-96; V: 1997-2001) were analyzed. In the first period the basic CT was MVPP (mechlorethamine, vinblastine, procarbazine, prednisone), while later B-DOPA (bleomycin, dacarbazine, vincristine, prednisone, doxorubicin) was gradually introduced alone or alternately with MVPP. In order to decrease the incidence of late complications, the dose of IF-RT from 45 Gy to 15-30 Gy was reduced in the next periods. In V period in 21 children with stage IA and IIA with favorable prognostic factors, CT alone was used. The probability of over 5-year: overall survival, relapse free survival and event free survival were in the I period: 92%, 83% and 77%, in the II period: 97%, 92% and 89%, in the III period: 97%, 93% and 91%, in the IV period: 95%, 91% and 90%, in the V period: 95%, 95% and 93%. Decreased rate of serious complications was also observed. Intensity of therapy should be tailored to the stage of disease, and to other significant prognostic factors. The current strategy of diagnosing and treatment of HD is aimed at balancing between the highest possible cure rates and risk of late complications.

Approximately 60 children aged 0-18 years are diagnosed of NBL each year in Poland. About 60% of all patients suffering from NBL have a chance for durable cure. Unfortunately the prognosis for patients within the high-risk group accounting for more than 50% of all NBL patients remains poor despite the introduction of more intensive chemotherapy regimens with radical surgery procedures and megachemotherapy with subsequent stem cell transplantation. Only one third of patients in this group can be cured. To improve the treatment results of the high-risk patient group and to decrease the rate of therapy related side effects current European treatment protocols have been introduced systematically in Poland. In February 2009 information about 389 patients (age 0.1-16.5 years) diagnosed between 2001 and 2008 were obtained. Results of therapy of 319 patients who started treatment from 2001 to 2007 were analyzed. Between 104 infants and 215 children over 1 year of age, stage 4 of disease was found in 25% and 54.5%, respectively. In this period additionally to European treatment protocols, two another protocols were used. Satisfactory treatment results were obtained in 104 infants (5-year event free survival /EFS/=82.6%), irrespective of the type of treatment protocol. Over 5-year EFS for children over 1 year of age in 1, 2 and 3 stage of disease was: 100%, 86.3% and 64.5%, respectively. On the contrary, 107 patients with 4 stage of disease achieved the 5-year EFS of 27% only. Treatment results obtained in patients treated according to the European HR-NBL-1/ESIOP protocol were better than for patients treated according to other treatment protocols (5-year EFS: 31.1% and 16.4%, respectively), but difference between these groups was not significant. Between 2001 and 2007 data reporting increased to 81% from 19% noted earlier. Unfortunately, results of treatment for children over 1 year of age remain still unsatisfactory. That is why there is a need of improvement of modern, unified treatment realization as well as better data reporting. For realization of these aims adequate financial support is essential.

Currently over 90% of children and adolescents with Hodgkin's disease (HD) can be cured thanks to use of multidrug chemotherapy (CT) combined with involved-field radiotherapy (IF-RT). However, the intensive treatment may increase the risk of late complications which may impair the patients' quality of life. In order to decrease the incidence of late complications the protocol with limited use of IF-RT was introduced in centers of Polish Pediatric Leukemia/Lymphoma Study Group (PPLLSG). This study presents the treatment results of patients treated with CT only in comparison with the therapy results of children treated with CT and IF-RT. From 1997 to 2006, 634 children (age: 2-22,5 years) with HD were treated in 14 oncological centers of PPLLSG. Majority of patients received CT (3-8 cycles of MVPP/B-DOPA) combined with IF-RT. In 45 patients with IA-IIA stages presenting favorable risk factors (small mediastinal tumor, peripheral nodular mass of a maximum diameter6 cm, involvement of less than three nodular regions, ESR50 mm after 1 h, histologic type other than lymphocyte depletion and very good treatment response assessed after 3 CT cycles) IF-RT was omitted. Among 634 children first complete remission (RC) was not achieved in 2.4% of patients. Relapses occurred in 24 children (3.9%). The rates of 5-year overall survival (OS), relapse-free survival (RFS) and event-free survival (EFS) were 97%, 96% i 92%, respectively. All patients treated with CT only remain in first CR. All serious late complications (including 7 second neoplasms) occurred in patients treated with CT combined with RT. Seven children died because of severe complications, among them two in first CR (aplastic anemia, sepsis). Our results show that the use of CT only in precisely selected group of patients with HD do not impair the treatment results and may decrease the risk of late life threatening complications. Treatment response assessment with the use of PET may in future increase the number of patients treated without RT and limit the need of the use of invasive diagnostic methods in patients with residual mass.