Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0026986 (myelodysplastic syndrome)
 14,926 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Alkylating agents and topoisomerase II inhibitors are mutagenic cytotoxic drugs which may induce therapy-related acute myeloid leukemia or myelodysplasia. The frequency of these complications depends on the type of agent used, its dosage, and the duration of treatment. Commonly used protocols for adjuvant chemotherapy of breast cancer, such as the CMF or AC protocols, are associated with a leukemia rate of 0.2 to 0.5 % after 10 years. Intensification of chemotherapy or additional radiotherapy lead to a significant increase in the incidence of leukemia. The prognosis of therapy-related leukemia is dismal. Therefore, it appears mandatory to restrict adjuvant chemotherapy to those patients who are the most likely to benefit from it.
 ...
PMID:[Therapy-induced leukemia -- an underestimated complication of antineoplastic chemotherapy?]. 1603 5

A 50-year-old man was referred to our department with esophageal cancer. He had past history of small cell lung cancer treated with chemoradiation therapy 10 years prior. The disease was evaluated as complete remission after chemoradiation therapy and no recurrence had been observed. Esophagectomy accompanying postoperative chemotherapy was applied, but he died of secondary myelodysplastic syndrome with its acute myeloblastic transformation. Risk evaluation revealed a high incidence of esophageal cancer after radiation therapy and hematological malignancies after chemoradiation therapy in usual regimen with topoisomerase inhibitor or alkylating agents. Chemoradiation therapy is thought to be one of a few highly effective therapeutic alternatives and many complete remission cases have been reported in small cell lung cancer or esophageal cancer. In post-therapeutic follow up of patients with such past therapeutic histories, we should be cautious about secondary malignancies even if primary malignant disease was evaluated as complete remission in long past history.
 ...
PMID:Secondary myelodysplastic syndrome after small cell lung cancer and esophageal cancer. 1610 15

Acute leukemias with balanced chromosomal translocations, protean morphologic and immunophenotypic presentations but generally shorter latency and absence of myelodysplasia are recognized as a complication of anti-cancer drugs that behave as topoisomerase II poisons. Translocations affecting the breakpoint cluster region of the MLL gene at chromosome band 11q23 are the most common molecular genetic aberrations in leukemias associated with the topoisomerase II poisons. These agents perturb the cleavage-religation equilibrium of topoisomerase II and increase cleavage complexes. One model suggests that this damages the DNA directly and leads to chromosomal breakage, which may result in untoward DNA recombination in the form of translocations. This review will summarize the evidence for topoisomerase II involvement in the genesis of translocations and extension of the model to acute leukemia in infants characterized by similar MLL translocations.
 ...
PMID:Topoisomerase II and the etiology of chromosomal translocations. 1685 31

Chronic myelomonocytic leukaemia (CMML) is a preleukaemic condition with myeloproliferative features, and classified as a part of myelodysplastic syndrome (MDS). Other than alkylating agents and topoisomerase II inhibitors, there is less evidence that chemotherapeutic drugs are associated with therapy-related CMML, acute leukaemia or MDS. We present a patient who developed CMML within 2 years of platinum-based chemotherapy for a metastatic non-small cell lung cancer. He received a cumulative dose of 240 mg/m(2) of cisplatin, and 1123 mg/m(2) of carboplatin before developing CMML. The cytogenetic study revealed trisomy 8. This is the first reported case that links platinum-based therapy with development of CMML with trisomy 8. Although the relationship between platinum therapy and the development of CMML is difficult to assess due to combinational nature of therapy in most cases, physicians should consider the possibility of CMML in patients with symptoms or signs suggestive of haematologic malignancy after platinum therapy.
 ...
PMID:Chronic myelomonocytic leukaemia after platinum-based therapy for non-small cell lung cancer: case report and review of the literature. 1688 13

Recurring chromosome abnormalities are strongly associated with certain subtypes of leukemia, lymphoma and sarcomas. More recently, their potential involvement in carcinomas, i.e. prostate cancer, has been recognized. They are among the most important factors in determining disease prognosis, and in many cases, identification of these chromosome abnormalities is crucial in selecting appropriate treatment protocols. Chromosome translocations are frequently observed in both de novo and therapy-related acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). The mechanisms that result in such chromosome translocations in leukemia and other cancers are largely unknown. Genomic breakpoints in all the common chromosome translocations in leukemia, including t(4;11), t(9;11), t(8;21), inv(16), t(15;17), t(12;21), t(1;19) and t(9;22), have been cloned. Genomic breakpoints tend to cluster in certain intronic regions of the relevant genes including MLL, AF4, AF9, AML1, ETO, CBFB, MYHI1, PML, RARA, TEL, E2A, PBX1, BCR and ABL. However, whereas the genomic breakpoints in MLL tend to cluster in the 5' portion of the 8.3 kb breakpoint cluster region (BCR) in de novo and adult patients and in the 3' portion in infant leukemia patients and t-AML patients, those in both the AML1 and ETO genes occur in the same clustered regions in both de novo and t-AML patients. These differences may reflect differences in the mechanisms involved in the formation of the translocations. Specific chromatin structural elements, such as in vivo topoisomerase II (topo II) cleavage sites, DNase I hypersensitive sites and scaffold attachment regions (SARs) have been mapped in the breakpoint regions of the relevant genes. Strong in vivo topo II cleavage sites and DNase I hypersensitive sites often co-localize with each other and also with many of the BCRs in most of these genes, whereas SARs are associated with BCRs in MLL, AF4, AF9, AML1, ETO and ABL, but not in the BCR gene. In addition, the BCRs in MLL, AML1 and ETO have the lowest free energy level for unwinding double strand DNA. Virtually all chromosome translocations in leukemia that have been analyzed to date show no consistent homologous sequences at the breakpoints, whereas a strong non-homologous end joining (NHEJ) repair signature exists at all of these chromosome translocation breakpoint junctions; this includes small deletions and duplications in each breakpoint, and micro-homologies and non-template insertions at genomic junctions of each chromosome translocation. Surprisingly, the size of these deletions and duplications in the same translocation is much larger in de novo leukemia than in therapy-related leukemia. We propose a non-homologous chromosome recombination model as one of the mechanisms that results in chromosome translocations in leukemia. The topo II cleavage sites at open chromatin regions (DNase I hypersensitive sites), SARs or the regions with low energy level are vulnerable to certain genotoxic or other agents and become the initial breakage sites, which are followed by an excision end joining repair process.
 ...
PMID:Chromatin structural elements and chromosomal translocations in leukemia. 1689 85

Secondary leukemia is a poorly defined term that often refers to the development of acute myeloid leukemia (AML) following the history of a previous disease, such as a myelodysplastic syndrome or a chronic myeloproliferative disorder. Secondary leukemia can also be a consequence of treatment with chemotherapy, including alkylating agents and topoisomerase II inhibitors, and/or radiotherapy, or due to exposure to environmental carcinogens. Outcomes for this large and variable group of patients with secondary AML have been poor compared to people who develop AML de novo. The question arises whether a diagnosis of secondary leukemia per se indicates a poor prognosis or whether their bad outcomes result from an association with certain morphologic and biologic characteristics. Morphologic dysplasia in de novo AML is related to unfavorable cytogenetics, but has no independent prognostic relevance under the conditions of intensive chemotherapy. While there is no significant correlation between cytogenetic risk groups and dysplasia, cytogenetic features do have an impact on outcome among both de novo and secondary AML patients. In various subgroups of secondary AML, the spectrum of cytogenetic abnormalities is similar to de novo AML, but the frequency of abnormalities associated with unfavorable and intermediate risk cytogenetics, such as a complex karyotype, trisomy 8, monosomy 7, and others, is higher in secondary AML. The survival of patients with therapy-related myeloid leukemia (t-AML) is generally shorter than for those with de novo AML within the same cytogenetic risk group. Across the population of t-AML, however, survival varies according to cytogenetic risk group, with longer survival in patients with favorable-risk karyotypes. The term secondary AML is too broad and imprecise to be of importance and should not be used. These AML patients should be enrolled on front-line chemotherapy trials and should be stratified by pretreatment disease status and exposure history, if necessary. Most importantly, the molecular and genetic differences that appear to determine the phenotype and the outcome of these patients need to be investigated further.
 ...
PMID:Is secondary leukemia an independent poor prognostic factor in acute myeloid leukemia? 1733 52

Therapy-related myelodysplastic syndrome/acute myeloid leukemia (t-MDS/AML) is an increasingly recognized treatment complication in patients treated with radiotherapy or chemotherapy for previous hematologic malignancies or solid tumors. Distinct clinical entities have been described according to the primary treatment, corresponding to defined genetic lesions. Chromosome 7 and/or 5 losses or deletions are typical of alkylating agent-induced AML, while development of t-AML with balanced translocations involving chromosome bands 11q23 and 21q22 has been related to previous therapy with drugs targeting DNA-topoisomerase II. In addition, antimetabolites, and in particular the immunosuppressant azathioprine, have been shown to induce defective DNA-mismatch repair. This could promote survival of misrepaired cells giving rise to the leukemic clone. Individual predisposing factors, including polymorphisms in detoxification and DNA repair enzymes have been identified. Their combination may significantly increase the risk of t-MDS/AML. Among patients with hematologic malignancies, long-term survivors of Hodgkin's lymphoma are exposed to an increased risk of t-MDS/AML, particularly when receiving MOPP-based, and escalated BEACOPP regimens, and when alkylators are combined with radiotherapy. Patients with Hodgkin's and non-Hodgkin's lymphoma are at highest risk when total body irradiation followed by autologous stem cell transplantation is used as rescue or consolidation therapy. The addition of granulocyte-colony-stimulating factor and radiotherapy plays a significant role in t-AML following treatment of children with acute lymphoblastic leukemia. In non-hematologic malignancies, treatment for breast cancer and germ-cell tumors has been associated with a 1-5% lifetime risk of both lymphoid as well as myeloid leukemia. In all cases the risk of t-MDS/AML drops sharply by 10 years after treatment.
 ...
PMID:Therapy-related leukemia and myelodysplasia: susceptibility and incidence. 1776 13

Balanced chromosome rearrangements are the hallmark of therapy-related leukemia that develops in patients treated with topoisomerase II inhibitors. Many of these rearrangements involve recurrent chromosomal sites and associated genes (11q23/MLL, 21q22.3/AML1, and 11p15/NUP98), which can interact with a variety of partner genes. One such rearrangement is the rare t(1;11)(q23;p15), which involves juxtaposition of the homeobox gene PMX1 (PRRX1) and NUP98. We report on an additional patient with t(1;11) who presented with myelodysplastic syndrome (MDS) subsequent to treatment for a pleomorphic liposarcoma. With time, the patient's disorder progressed to acute myelomonocytic leukemia with cytogenetic evidence of clonal evolution. To our knowledge, this is the first report of a patient presenting with a myelodysplastic syndrome with isolated t(1;11) (q23;p15), which evolved into therapy-related acute myeloid leukemia (t-AML). This patient is the third reported with this cytogenetic rearrangement and t-AML, and is compared with the other two reports of t(1;11)(q23;p15).
 ...
PMID:Rare t(1;11)(q23;p15) in therapy-related myelodysplastic syndrome evolving into acute myelomonocytic leukemia: a case report and review of the literature. 1788 7

In therapy-related myelodysplasia (t-MDS) and acute myeloid leukemia (t-AML), at least eight alternative genetic pathways have been defined based on characteristic recurrent chromosome abnormalities. Patients presenting as t-MDS and patients presenting as overt t-AML cluster differently in these pathways. The cytogenetic pattern depends on the type of leukemogenic therapy received: alkylating agents, topoisomerase II inhibitors, or radiotherapy. Three types of gene mutations are observed in MDS and AML: (1) Activating mutations of genes in the tyrosine kinase-RAS/BRAF signal transduction pathway, leading to increased cell proliferation (Class I mutations); (2) Inactivating mutations of genes encoding hematopoietic transcription factors, resulting in disturbed cell differentiation (Class II mutations); and (3) Inactivating mutations of the tumor suppressor gene p53. At least 14 different genes have been identified as mutated in t-MDS and t-AML, clustering differently and characteristically in the eight genetic pathways. Class I and Class II mutations are significantly associated, indicating their cooperation in leukemogenesis The chromosome aberrations and gene mutations detected in the therapy-related and in the de novo subsets of MDS and AML are identical, although the frequencies with which they are observed may differ. Hence, therapy-related and de novo MDS and AML are identical diseases and should be subclassified and treated similarly.
 ...
PMID:Genetic pathways in the pathogenesis of therapy-related myelodysplasia and acute myeloid leukemia. 1802 56

Therapy-related myelodysplastic syndrome and acute myeloid leukemia (t-MDS/t-AML) have been reported only rarely following treatment of AML. We report five patients treated for de novo AML who developed t-MDS/t-AML, all with chromosome 7 abnormalities, including -7, del(7)(q22q36) and del(7)(p11.22p22). All had been treated with cytarabine, topoisomerase 2 inhibitors and granulocyte or granulocyte-monocyte colony-stimulating factor and three with alkylating agents as part of autologous transplant regimens. These cases further document t-MDS/t-AML as a complication of therapy for AML. Presence of chromosome 7 abnormalities in patients with and without prior alkylating agent therapy suggests possible association with the antimetabolite cytarabine.
 ...
PMID:Therapy-related myelodysplastic syndrome and acute myeloid leukemia following treatment of acute myeloid leukemia: possible role of cytarabine. 1809 51


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>