ABSTRACT
The case history of two sisters with pyridoxine-refractory familial sideroblastic anemia (FSA) is presented in which one developed a myelodysplastic syndrome (MDS) with monosomy for chromosome 5. Bone marrow examination of both patients at diagnosis showed erythroid hyperplasia with more than 50% ring sideroblasts. Karyotypic analysis initially showed a normal 46, XX karyotype in both of the children. Therapeutic trials with pyridoxine, prednisone, and erythropoietin were unsuccessful. The first patient required regular transfusions and developed a significant hemosiderosis. At the age of 9 years, 7.5 years after the diagnosis of FSA, refractory anemia with excess of blasts (RAEB) was diagnosed. Bone marrow cytogenetic analysis revealed a clone with monosomy for chromosome 5. Her sister's illness was detected at the age of 12 years. She has a more benign course of disease, remains largely transfusion independent and until now shows no signs of myelodysplasia. To our knowledge this is the first observation of a transition of FSA to MDS accompanied by the appearance of a chromosomal abnormality. FSA might be another type of bone marrow failure syndrome, therefore close follow-up of these patients may be necessary.
Subject(s)
Anemia, Sideroblastic/complications , Anemia, Sideroblastic/genetics , Chromosomes, Human, Pair 5 , Myelodysplastic Syndromes/complications , Myelodysplastic Syndromes/genetics , Anemia, Refractory, with Excess of Blasts/complications , Anemia, Sideroblastic/drug therapy , Child , Female , Humans , Infant , Karyotyping , Monosomy , Myelodysplastic Syndromes/drug therapy , Pyridoxine/therapeutic useABSTRACT
The better prognosis of acute lymphoblastic leukemia (ALL) than of acute non-lymphoblastic leukemia (ANLL) in children, and the often observed better prognosis of myeloid-antigen (MyAg) negative ALL than of MyAg-positive ALL, may be related to differences in cellular drug resistance. We therefore compared the resistance to 12 drugs of 125 ALL and 28 ANLL samples with the MTT assay. ALL samples were median > 75-fold more sensitive to the glucocorticoids prednisolone and dexamethasone (p < 0.00001), and 2-fold more sensitive to vincristine (p = 0.05) than ANLL samples. Differences for the other drugs were not significant. MyAg-negative ALL samples were more sensitive to glucocorticoids than MyAg-positive ALL-samples (p < or = 0.04). Prednisolone, and dexamethasone if tested, had a stimulatory effect on leukemic cell survival in 36% of ANLL, but in only 2% of ALL samples (p < 0.0001). Vincristine, and vindesine if tested, had a similar effect in 11% of ANLL, and in 4% of ALL samples (p = 0.11). We conclude that the more favorable response of ALL against ANLL to combination chemotherapy in children may be explained by the higher antileukemic activity of glucocorticoids and of vincristine in ALL, while none of the drugs was more active in ANLL. Similarly, the better prognosis of MyAg-negative ALL than of MyAg-positive ALL may be explained by a relative sensitivity to glucocorticoids. Glucocorticoids and vinca-alkaloids induced leukemia cell proliferation in part of the samples, most frequently in ANLL. The findings may be useful in the design of new chemotherapeutic regimens for ALL and ANLL.
Subject(s)
Antineoplastic Agents/pharmacology , Leukemia, Myeloid, Acute/drug therapy , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Adolescent , Antigens, Differentiation, Myelomonocytic/physiology , Child , Child, Preschool , Drug Resistance , Drug Screening Assays, Antitumor , Female , Humans , Infant , Male , Prognosis , Tumor Cells, Cultured/drug effectsABSTRACT
Glucocorticoids (GC) are being used in the treatment of childhood leukemia for several decades, most successfully in newly diagnosed acute lymphoblastic leukemia (ALL). However, GC resistance is seen in 10-30% of untreated ALL patients, and is much more frequent in relapsed ALL and in acute nonlymphoblastic leukemia (ANLL). Sensitivity or resistance to GC can be measured using a cell culture drug resistance assay. For this purpose, we use the colorimetric methyl-thiazol-tetrazolium (MTT) assay. We have shown that GC resistance in childhood leukemia is related to clinical and cell biological features, and to the clinical outcome after multi-drug chemotherapy. These results are summarized in this review. In addition, we describe the apoptotic 'cell-lysis pathway' by which GC exert their antileukemic activity. This description provides a model to discuss the mechanisms of GC resistance, and to summarize the relevant literature. Possible levels of resistance relate to the diffusion of GC through the cell membrane, binding to the GC receptor (GCR), activation of the GC-GCR complex, translocation of the complex into the nucleus, binding to DNA, endonuclease-mediated DNA fragmentation, and DNA repair. A low number of GCR has been shown to be the cause of resistance in some children with ALL. However, GC resistance is likely to be caused at the post-receptor level in most leukemias. Unfortunately, there is still a lack of knowledge relating to the clinical relevance of mechanisms of GC resistance at the post-receptor level. Studies on the mechanisms of GC resistance other than those directly related to the GCR should be initiated, especially if patient material is used, as the results might indicate ways to circumvent or modulate GC resistance. A further increase in our knowledge regarding the relation between GC resistance and patient and cell biological features, the clinical relevance of GC resistance, and the mechanisms of GC resistance in leukemia patients, may contribute to further improvement in the results of GC therapy in leukemia.
Subject(s)
Glucocorticoids/pharmacology , Leukemia, Myeloid, Acute/drug therapy , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Acute Disease , Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Apoptosis/drug effects , Cell Nucleus/metabolism , Child , Child, Preschool , Colorimetry , DNA Damage , DNA Repair , DNA, Neoplasm/metabolism , Diffusion , Down-Regulation , Drug Resistance , Glucocorticoids/pharmacokinetics , Glucocorticoids/therapeutic use , Humans , Infant , Leukemia, Myeloid, Acute/pathology , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Precursor Cell Lymphoblastic Leukemia-Lymphoma/pathology , Prognosis , Receptors, Glucocorticoid/genetics , Receptors, Glucocorticoid/metabolism , Salvage Therapy , Treatment OutcomeABSTRACT
We report a case of an unusual giant congenital tumor presenting in a newborn infant as a large exophytic mass emerging from the left orbit. After enucleation orbital recurrence developed within 14 days. No anti-tumor treatment was given and the child died at the age of 4 weeks. The histopathological and cytogenetical analysis of the tumor is presented. The tumor was diagnosed as a retinoblastoma but we could not exclude the possibility of a neuroblastoma.
Subject(s)
Eye Neoplasms/congenital , Orbital Neoplasms/congenital , Retinoblastoma/congenital , Eye Neoplasms/pathology , Humans , Infant, Newborn , Neoplasm Invasiveness , Neoplasm Recurrence, Local/pathology , Orbital Neoplasms/pathology , Retinoblastoma/pathologyABSTRACT
Mitoxantrone (MIT) has not been studied as a single agent in children with untreated leukemia. The antileukemic activity of MIT in these patients and its activity in relation to clinical and cell biological features is unknown. We studied the in vitro cytotoxicity of MIT, daunorubicin (DNR) and doxorubicin (DOX) in untreated childhood acute lymphoblastic leukemia (ALL, n = 131) and acute nonlymphoblastic leukemia (ANLL, n = 20) samples, using the MTT assay. There were marked interindividual differences in resistance to all three drugs. A strong, significant cross-resistance was found in ALL between MIT, DNR and DOX. All samples of the T-lineage, a prognostically unfavorable immunophenotype, however, were significantly more resistant to DNR and DOX, but not to MIT, than common or pre-B ALL samples. ALL cells from children with a prognostically unfavorable age at diagnosis, especially those < 2 years, showed a relative resistance to all three drugs compared to the intermediate age-group. This was found within all patients, but also within the common or pre-B ALL cases only. Sex, white blood cell count, or FAB type was not related to in vitro drug resistance. None of the three drugs showed an overall preferential activity in ALL or ANLL. We conclude that the in vitro antileukemic activity of MIT, DNR and DOX is related to certain clinical and cell biological features. There were no major differences between the three drugs in antileukemic activity, except that T-ALL samples were more resistant than common or pre-B ALL samples to DNR and DOX, while MIT was equally active in these two immunophenotypes.
Subject(s)
Antineoplastic Agents/pharmacology , Daunorubicin/toxicity , Doxorubicin/toxicity , Mitoxantrone/toxicity , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Adolescent , Antineoplastic Agents/toxicity , Child , Child, Preschool , Daunorubicin/pharmacology , Doxorubicin/pharmacology , Drug Resistance , Drug Screening Assays, Antitumor , Female , Humans , Infant , Male , Mitoxantrone/pharmacology , Tumor Cells, Cultured/drug effectsABSTRACT
The results of current treatment of relapsed childhood acute lymphoblastic leukemia (ALL) are discussed, together with some recent developments which (might) influence such treatment. At present more than 95% of children with ALL will achieve a complete remission (CR), and +/- 70% will remain in CR. Nevertheless, 20-30% of the patients suffer a relapse, which implies a less favorable prognosis. However, after intensive treatment a part of these patients will have a prolonged second complete remission: 30-50% of children with a late relapse and 0-20% of children with an early relapse. It is important to prevent the occurrence of a relapse. The identification at diagnosis of patients at high risk for a relapse, and a subsequent more specific and more intensive treatment of these patients might contribute to that goal. Well-known risk factors are briefly mentioned, factors of which the prognostic significances is therapy-dependent. In addition, the treatment of relapsed ALL needs further improvement. Some alternatives to achieve this goal are discussed, including the role of in vitro cytostatic drug resistance testing.
Subject(s)
Antineoplastic Combined Chemotherapy Protocols/therapeutic use , Precursor Cell Lymphoblastic Leukemia-Lymphoma/drug therapy , Bone Marrow Transplantation , Child , Child, Preschool , Female , Growth Substances/therapeutic use , Humans , Immunotherapy/methods , Infant , Male , Precursor Cell Lymphoblastic Leukemia-Lymphoma/physiopathology , Precursor Cell Lymphoblastic Leukemia-Lymphoma/therapy , Prognosis , Recurrence , Remission Induction , Tumor Stem Cell AssayABSTRACT
The prognostic value of morphometric features was studied in a group of 33 children with acute lymphoblastic leukemia (ALL) and compared with clinical and hematologic parameters. Air dried, May-Grünwald-Giemsa-stained specimens were prepared from iliac crest biopsies, and for each patient, 150 blasts and their nuclei were selected according to a stratified selection method and measured on a graphic tablet system. Univariate overall survival analysis showed the French-American-British (FAB) classification to be the strongest clinical parameter (P less than .0001). However, the significance was mainly due to the fact that both L3 cases died; the results for L1 and L2 were less satisfactory, with a survival rate (at 10 years) of 69% for the 26 L1 cases and 80% for the five L2 cases. The nuclear/cytoplasmic (N/C) ratio was the best morphometric feature (P less than .0001) and provided more satisfactory classification results than did FAB: only 2 of the 21 (10%) cases with N/C ratios greater than 0.90 died (7 and 9.5 years after the diagnosis, respectively), and 9 of the 12 (75%) cases with N/C ratios greater than or equal to 0.90 died. For recurrence-free survival analysis, essentially the same results were obtained. The N/C ratio retained its significant prognostic value after recurrence: 11 of the 15 patients with eventual recurrences died; 9 of them had an (original) N/C ratio less than or equal to 0.90. Three of the four recurring cases that survived after recurrence had an N/C ratio greater than 0.90 (P less than .03).(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Bone Marrow/pathology , Ilium/pathology , Precursor Cell Lymphoblastic Leukemia-Lymphoma/pathology , Cell Nucleus/ultrastructure , Child , Child, Preschool , Cytoplasm/ultrastructure , Female , Histocytological Preparation Techniques , Humans , Infant , Male , Prognosis , Survival AnalysisABSTRACT
UNLABELLED: Gonadal function was evaluated in 23 men (aged 14.8-28.8 years) treated in childhood with cytotoxic drugs for a solid tumour. Group 1 (N = 14) had been treated with non-alkylating drugs only, while group 2 (N = 9) received the alkylating drug cyclophosphamide in addition (range 3.8-19.5 g/m2). Median age at the start of treatment was 4.6 years (range 0.6-16.1) in group 1 and 13.9 years (range 3.7-16.9) in group 2. Data of the patients were compared with a reference group consisting of 14 normal men. Almost all patients of both groups showed normal development of puberty; 13 of the 14 men in group 1 showed normal hormonal values. In group 2, basal LH and FSH as well as the LH and FSH responses to GnRH showed higher levels compared to those of a reference group (p less than 0.001). Correlation analysis showed an evident correlation between the total dose of received cyclophosphamide and the basal FSH level (r = 0.78; p = 0.002), the FSH response to GnRH (r = 0.73; p = 0.002) and the LH response to GnRH (r = 0.67; p = 0.002). There was no correlation between the hormonal parameters and the doses of the other cytotoxic drugs. Semen analysis showed azoospermia in four boys of group 2 and in none of group 1. Two patients in group 2 had an elevated FSH response to GnRH while their semen analysis was normal. CONCLUSIONS: (1) There is a dose-response relationship between the basal FSH, the LH and FSH responses to GnRH and the dose of cyclophosphamide.(ABSTRACT TRUNCATED AT 250 WORDS)
Subject(s)
Cyclophosphamide/adverse effects , Follicle Stimulating Hormone/metabolism , Luteinizing Hormone/metabolism , Testicular Diseases/chemically induced , Adolescent , Adult , Gonadotropin-Releasing Hormone , Humans , Male , Puberty , Rhabdomyosarcoma/drug therapy , Sarcoma, Ewing/drug therapy , Semen/cytology , Sperm Count , Testicular Diseases/pathology , Testis/pathology , Wilms Tumor/drug therapyABSTRACT
In vitro drug sensitivity of leukaemic cells might be influenced by the contamination of such a sample with non-malignant cells and the sample source. To study this, sensitivity of normal peripheral blood (PB) lymphocytes to a number of cytostatic drugs was assessed with the MTT assay. We compared this sensitivity with the drug sensitivity of leukaemic cells of 38 children with acute lymphoblastic leukaemia. We also studied a possible differential sensitivity of leukaemic cells from bone marrow (BM) and PB. The following drugs were used: Prednisolone, dexamethasone, 6-mercaptopurine, 6-thioguanine, cytosine arabinoside, vincristine, vindesine, daunorubicin, doxorubicin, mafosfamide (Maf), 4-hydroperoxy-ifosfamide, teniposide, mitoxantrone, L-asparaginase, methotrexate and mustine. Normal PB lymphocytes were significantly more resistant to all drugs tested, except to Maf. Leukaemic BM and PB cells from 38 patients (unpaired samples) showed no significant differences in sensitivity to any of the drugs. Moreover, in 11 of 12 children with acute leukaemia of whom we investigated simultaneously obtained BM and PB (paired samples), their leukaemic BM and PB cells showed comparable drug sensitivity profiles. In one patient the BM cells were more sensitive to most drugs than those from the PB, but the actual differences in sensitivity were small. We conclude that the contamination of a leukaemic sample with normal PB lymphocytes will influence the results of the MTT assay. The source of the leukaemic sample, BM or PB, does not significantly influence the assay results.
Subject(s)
Antineoplastic Agents/pharmacology , Bone Marrow/pathology , Leukemia, Myeloid, Acute/pathology , Lymphocytes/cytology , Precursor Cell Lymphoblastic Leukemia-Lymphoma/pathology , Adult , Cell Survival/drug effects , Cells, Cultured , Child , Drug Screening Assays, Antitumor , Humans , Lymphocytes/drug effects , Reference ValuesABSTRACT
A newborn child with neonatal neutropenia as a result of the presence of maternal IgG isoantibodies against neutrophil granulocyte blood group antigens is reported. Mechanism, diagnostics and therapy of the disease are discussed. The diagnosis not only has consequences for the child, but also for the mother and following pregnancies. A review of the most important causes of neonatal neutropenia is given.
Subject(s)
Blood Group Antigens/immunology , Isoantibodies/immunology , Neutropenia/immunology , Female , Humans , Infant, Newborn , Infant, Premature, Diseases/immunology , Male , Maternal-Fetal Exchange , Neutropenia/congenital , PregnancyABSTRACT
An 11-year-old girl being treated with DNA-recombinant growth hormone therapy presented with proximal limb weakness. Laboratory studies were negative. A few months later she presented with acute lymphoblastic leukemia (ALL). A diagnosis of carcinomatous neuromyopathy was made. After successful treatment of the leukemia the symptoms subsided and did not recur.
Subject(s)
DNA, Recombinant/therapeutic use , Neuromuscular Diseases/etiology , Pituitary Hormones/therapeutic use , Precursor Cell Lymphoblastic Leukemia-Lymphoma/complications , Child , Female , Humans , Pituitary Hormones/adverse effects , Precursor Cell Lymphoblastic Leukemia-Lymphoma/chemically inducedABSTRACT
Cytosine-arabinoside (ARA-C) in low doses induces complete remissions in myelodysplastic syndromes and acute leukemia. Evidence is accumulating that these remissions are not reached by differentiation induction but through cytotoxicity. In HL60 cells differentiation was measured by a comprehensive panel of quantitative and qualitative markers of maturation. After exposure to ARA-C (10(-7) M) for 4 days HL60 cells did not mature morphologically. Cell volume increased. The increase in esterase activity was small and did not reach the amount measured in normal monocytes. There was no significant difference in latex phagocytosis and NBT reduction between cultures with and without ARA-C. HL60 cells were arrested in S-phase and clonogenic capacity persisted. The observed changes after exposure to ARA-C seem to be caused by impeded cell division while synthesis of protein continues. We conclude that ARA-C in low dose exerts its effect by halting proliferation through cytotoxic effects and not by differentiation induction.
Subject(s)
Cytarabine/administration & dosage , Leukemia, Promyelocytic, Acute/pathology , Cell Differentiation/drug effects , Cell Line/drug effects , Cytarabine/therapeutic use , Humans , Leukemia, Promyelocytic, Acute/drug therapy , Tumor Cells, Cultured/drug effects , Tumor Cells, Cultured/pathologyABSTRACT
DUP 785 (NSC 368390; Brequinar sodium) is a new inhibitor of pyrimidine de novo biosynthesis with antitumor activity against several experimental tumors. DUP 785 inhibits the mitochondrial enzyme dihydroorotate dehydrogenase, blocking the conversion of dihydroorotate to orotate. We examined the influence of exposure time to DUP 785 on its growth-inhibitory effects in L1210 murine leukemia and WiDR human adenocarcinoma cells and the effects of pyrimidine (deoxy) nucleosides on reversal of growth-inhibition. The results were correlated with changes in intracellular pyrimidine nucleotide pools and cell cycle distribution. In L1210 cells, a continuous exposure to 25 microM DUP 785 up to 96 hr caused complete growth inhibition. A 2 hr exposure of cells to the drug did not affect growth. In WiDR cells, exposure to the drug for 1-24 hr, followed by cultivation in drug-free medium resulted in recovery of growth. However, cells exposed to the drug for 48 hr or longer were not able to resume growth when recultured in drug-free medium. Reversal studies were performed to know whether selective depletion of one of the pyrimidine (deoxy) nucleotides might be related to the growth-inhibitory effects of DUP 785. Neither thymidine, deoxycytidine alone, deoxycytidine plus tetrahydrouridine; nor cytidine plus tetrahydrouridine added after 24 hr were able to reverse cell growth inhibition induced by 25 microM DUP 785. However, uridine and cytidine alone reversed growth inhibition. UTP and CTP pools in L1210 cells decreased to about 30-40% of control levels after 4 hr of drug exposure, while dTTP and dCTP pools decreased to about 30% of control levels. There were no significant changes in purine nucleotide pools. In WiDR cells, UTP and CTP pools decreased rapidly after drug exposure and were substantially depleted after 24 hr. Reculture of cells in drug-free medium resulted in a significant recovery of UTP and CTP levels only for cells exposed to DUP 785 for 1-24 hr. For cells exposed to the drug for 48 and 72 hr recovery of nucleotide pools was minimal. In L1210 cells, a 12-hr exposure to the drug caused an accumulation of cells in the early S-phase. In WiDR cells, there was a clear accumulation of cells in the S-phase of the cell cycle after 24 hr drug exposure.(ABSTRACT TRUNCATED AT 400 WORDS)
Subject(s)
Biphenyl Compounds/pharmacology , Growth Inhibitors , Animals , Biphenyl Compounds/administration & dosage , Cell Cycle/drug effects , Cell Division/drug effects , Deoxyribonucleotides/metabolism , Dihydroorotate Oxidase/antagonists & inhibitors , Dose-Response Relationship, Drug , Drug Administration Schedule , Humans , Mice , Pyrimidine Nucleotides/metabolism , Ribonucleotides/metabolism , Time Factors , Tumor Cells, CulturedABSTRACT
Bone marrow samples from 8 children treated for acute lymphoblastic leukemia (ALL) were investigated at cessation of cytostatic treatment and during 18 months thereafter. The course of the percentage of lymphoid cells and characterization of these cells by means of monoclonal antibodies, peanut agglutinin (PNA) binding and S-phase determination are shown. The percentage of lymphocytes rises in the first 1.5 months, followed by a non-significant decline. The percentage of cells in S-phase is higher at 0 months than at 6, 15 and 18 months. The percentage of T-cells does not change significantly. In the first 1.5 months a sudden rise in the percentage of common-ALL-antigen (cALLA)-positive lymphocytes occurs. The number of B-cells rises to a peak at 6 months. PNA positively increases to a maximum at 3 months and is correlated with positivity for markers of the B-cell lineage. The percentages of B-cells, cALLA-positive, and PNA-positive lymphocytes do not change significantly after they reach their maximum values and are still high at 18 months. Our results show that after cessation of chemotherapy for ALL a lymphoid cell regeneration occurs in the bone marrow consisting of cells of the B-cell lineage; many of these are cALLA-positive, but are discernible from their malignant counterparts by PNA-positivity.
Subject(s)
Bone Marrow/physiopathology , Leukemia, Lymphoid/genetics , Lymphocytes/immunology , Regeneration , Antibodies, Monoclonal , Bone Marrow/immunology , Bone Marrow/pathology , Cell Division , Child , Child, Preschool , Flow Cytometry , Humans , Immunoenzyme Techniques , Immunohistochemistry , Interphase , Lectins/metabolism , Leukemia, Lymphoid/pathology , Lymphocytes/physiopathology , Peanut Agglutinin , PhenotypeABSTRACT
Children with leukemia have to undergo many times painful procedures like bone-marrow aspiration and lumbar puncture. For reduction of anxiety and pain sensation good psychological support can be an important help. Often sedative drugs are used, or even general anaesthesia may be necessary. There is a need of a safe, short-acting and effective medication. Among the different possibilities the intravenous or rectal administration of midazolam seems to be very promising.
Subject(s)
Anesthesia/methods , Leukemia/therapy , Midazolam/administration & dosage , Pain/prevention & control , Analgesics/administration & dosage , Child , Child, Preschool , Humans , Leukemia/psychology , PremedicationABSTRACT
In acute myeloid leukaemia the peripheral leukocyte count is known to be a prognostic factor. The preserved capacity of leukaemic cells to mature has also been suggested to be one. In a series of 179 cases of adult acute myeloid leukaemia peripheral leukaemic cell count and degree of maturation were found to be inversely correlated. As the degree of maturation of leukaemic cells in peripheral blood was lower than that in bone marrow in the majority of cases, blast cells appear to be released more easily from the marrow than cells that have matured to some extent in the direction of the larger promyelocytic or promonocytic cell type. In a series of 35 cases we found peripheral blast cells to be smaller than those in bone marrow. Moreover, central blast cell diameter and peripheral leukaemic cell count were inversely correlated. Therefore, leukaemic cell size or some factor related to it may contribute to the preferential egress of small immature cells from the marrow. Differences in proliferative activity could not account for the inverse correlation between degree of maturation and leukaemic cell count.
Subject(s)
Leukemia, Myeloid, Acute/pathology , Leukocytes/pathology , Adult , Bone Marrow/pathology , Granulocytes , Humans , Leukemia, Myeloid, Acute/blood , Leukocyte Count , Mitosis , PrognosisABSTRACT
A case of metastatic Ewing's sarcoma to the skull is presented, demonstrating the superiority of magnetic resonance imaging over other imaging modalities to exclude CNS involvement. Precise delineation of different tumor components in extradural location contained in an intact dural rim together with compressed cortex showing no signs of tumorous involvement constituted a MRI appearance allowing us to exclude tumor outgrowth into the brain.