Use of the Polymerase Chain Reaction as a Complementary Method for the Detection of Central Nervous System Involvement in Children and Adolescents with Acute Lymphoblastic Leukemia.

BACKGROUND: Cytological analysis of the cerebrospinal fluid (CSF) remains the most widely used method for diagnosing central nervous system (CNS) involvement in acute lymphoblastic leukemia (ALL). This study aimed at evaluating the use of polymerase chain reaction (PCR), in comparison to other methods, for the assessment of the presence of blast cells in the CSF at the time of diagnosis of ALL. METHODS: This was a prospective, single-centre, study enrolling all patients up to the age of 18 years who were admitted to a university hospital between November 2011 and November 2014 with a diagnosis of ALL and from whom it was possible to draw a sufficient amount of CSF for analysis by conventional cytology (CT), immunophenotyping (IMP), and PCR. RESULTS: A total of 46 CSF samples from 44 ALL pediatric patients were included. CT was performed in all samples, IMP in 44, and PCR in 34. Thirteen (28.2%) samples showed positive results: two by CT, four by IMP, four by PCR, and three by both IMP and PCR. CONCLUSIONS: The results of this study showed that PCR should be considered a complementary method for the evaluation of the CSF in ALL patients at diagnosis.

A simplified minimal residual disease polymerase chain reaction method at early treatment points can stratify children with acute lymphoblastic leukemia into good and poor outcome groups.

BACKGROUND: Minimal residual disease is an important independent prognostic factor in childhood acute lymphoblastic leukemia. The classical detection methods such as multiparameter flow cytometry and real-time quantitative polymerase chain reaction analysis are expensive, time-consuming and complex, and require considerable technical expertise. DESIGN AND METHODS: We analyzed 229 consecutive children with acute lymphoblastic leukemia treated according to the GBTLI-99 protocol at three different Brazilian centers. Minimal residual disease was analyzed in bone marrow samples at diagnosis and on days 14 and 28 by conventional homo/heteroduplex polymerase chain reaction using a simplified approach with consensus primers for IG and TCR gene rearrangements. RESULTS: At least one marker was detected by polymerase chain reaction in 96.4% of the patients. By combining the minimal residual disease results obtained on days 14 and 28, three different prognostic groups were identified: minimal residual disease negative on days 14 and 28, positive on day 14/negative on day 28, and positive on both. Five-year event-free survival rates were 85%, 75.6%, and 27.8%, respectively (p<0.0001). The same pattern of stratification held true for the group of intensively treated children. When analyzed in other subgroups of patients such as those at standard and high risk at diagnosis, those with positive B-derived CD10, patients positive for the TEL/AML1 transcript, and patients in morphological remission on a day 28 marrow, the event-free survival rate was found to be significantly lower in patients with positive minimal residual disease on day 28. Multivariate analysis demonstrated that the detection of minimal residual disease on day 28 is the most significant prognostic factor. CONCLUSIONS: This simplified strategy for detection of minimal residual disease was feasible, reproducible, cheaper and simpler when compared with other methods, and allowed powerful discrimination between children with acute lymphoblastic leukemia with a good and poor outcome.

Association of the germline TP53 R337H mutation with breast cancer in southern Brazil.

BACKGROUND: The germline TP53-R337H mutation is strongly associated with pediatric adrenocortical tumors (ACT) in southern Brazil; it has low penetrance and limited tissue specificity in most families and therefore is not associated with Li-Fraumeni syndrome. However, other tumor types, mainly breast cancer, have been observed in carriers of several unrelated kindreds, raising the possibility that the R337H mutation may also contribute to breast tumorigenesis in a genetic background-specific context. METHODS: We conducted a case-control study to determine the prevalence of the R337H mutation by sequencing TP53 exon 10 in 123 women with breast cancer and 223 age- and sex-matched control subjects from southern Brazil. Fisher's test was used to compare the prevalence of the R337H. RESULTS: The R337H mutation was found in three patients but in none of the controls (p = 0.0442). Among the carriers, two had familial history of cancer meeting the Li-Fraumeni-like criteria. Remarkably, tumors in each of these three cases underwent loss of heterozygosity by eliminating the mutant TP53 allele rather than the wild-type allele. Polymorphisms were identified within the TP53 (R72P and Ins16) and MDM2 (SNP309) genes that may further diminish TP53 tumor suppressor activity. CONCLUSION: These results demonstrate that the R337H mutation can significantly increase the risk of breast cancer in carriers, which likely depends on additional cooperating genetic factors. These findings are also important for understanding how low-penetrant mutant TP53 alleles can differentially influence tumor susceptibility.