RasProtooncogene Activation in Acute Myeloid Leukemia and Related Disorders

Molecular epidemiology of hematological neoplasms--present status and future directions

The field of molecular epidemiology, using modern epidemiological approaches and taking the advantage of the advances in molecular biology can provide new tools for the exploration of etiological determinants, either environmental or hereditary, in the development of hematological neoplasms. It is now possible to identify some host susceptibility characteristics, to measure the effective dose of exposure, and to identify early, pre-clinical biological effects, using sensitive and specific biomarkers. The significant variation in the incidence of hematological neoplasms in different geographical areas, races, and age groups, the high rates of familial aggregation in certain populations, the involvement of protooncogenes and tumor suppressor genes in the development of hematological neoplasms, as well as of many environmental agents such as chemicals, radiation, and viruses, support the important role of molecular epidemiology in the investigation of the development of hematological neoplasms.

K-ras gene point mutation: a stable tumor marker in non-small cell lung carcinoma

K-ras gene point mutation is a highly frequent event in human malignancy. About one third of non-small cell lung cancer (NSCLC) patients harbor K-ras gene point mutational activations. This study investigates the prevalence of K-ras mutation in autopsy tumors with NSCLC, and the correlation of K-ras gene point mutations between primary tumors and metastases in NSCLC. Formalin-fixed, paraffin-embedded tissue sections of 15 primary lung tumors and their metastases, (obtained from autopsy), were examined for the presence of point mutations in K-ras gene codon 12, 13 and 61 by oligodeoxynucleotide hybridization analysis of DNA fragments, amplified by polymerase chain reaction (PCR). K-ras gene point mutations were detected in five cases of lung carcinoma, of which four were adenocarcinomas and one was squamous cell carcinoma. In each of these cases, identical K-ras gene mutations were found in the DNA of both the primary tumor and its corresponding distant metastases. Activating K-ras base-substitutions correlate well between the primary tumor and its corresponding metastases in NSCLC. In the negative cases where no K-ras mutation was found in the primary tumors, no newly acquired K-ras mutation appeared in the metastases. Our study indicates that K-ras point mutation serves as a stable tumor marker in NSCLC.

Long-term survivors in myelodysplastic syndromes: a report on 63 cases and comparison with short and intermediate survivors

Sixty-three of 373 patients (17%) with de novo myelodysplastic syndrome (MDS) survived more than 5 yr (long survivors). At diagnosis, they usually had no or only moderate cytopenias; 63% of them had marrow blasts < 5%; only 1 patient had circulating blasts; 60% had refractory anaemia (RA) or refractory anaemia with ringed sideroblasts (RARS); 19% of the 43 patients who were karyotyped had an abnormal clone, and only 2 patients had complex cytogenetic findings. Only 4 of the 63 patients progressed to another FAB type within 5 yr of diagnosis, from RA to refractory anaemia with excess of blasts (RAEB) or chronic myelomonocytic leukaemia (CMML). After 5 yr, 9 patients showed progression (including progression to AML in 5 patients). The other patients remained stable (43 cases) or died from cytopenias or unrelated disorders (11 cases). Except for 3 patients who achieved prolonged complete remission with intensive chemotherapy, and possibly 3 patients who responded to low dose Ara C, prolonged survival seemed to result mainly from the low natural course of the disease. Although, as expected, significant differences for age, cytopenias, circulating and bone marrow blasts, and karyotype were seen between short (< 2 yr) and long (> 5 yr) very few significant differences were seen between intermediate and long survivors. These 2 subgroups only differed by significantly lower age and higher haemoglobin level in long survivors. Multivariate scoring systems (Bournemouth, Sanz's and Lille scores) proved of relatively limited value in differentiating them.(ABSTRACT TRUNCATED AT 250 WORDS)