Chronic leukaemias

Epidemiology, treatment patterns and survival of chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) in Taiwan, 2006-2015

AIM/OBJECTIVE

Chronic lymphocytic leukaemia/small lymphocytic lymphoma (CLL/SLL) is one of the most frequent types of leukaemia/lymphoma in adults in Western countries. However, there are few studies regarding its epidemiology and treatment patterns in Asian countries.

METHODS

To investigate CLL/SLL in Asian populations, we identified CLL/SLL patients diagnosed during 2006 to 2015 from the Taiwan Cancer Registry Database and estimated the incidence. Further, patients diagnosed during 2008 to 2015 were included for the analysis of treatment patterns and survivals. Treatments for CLL/SLL were retrieved from the Taiwan's National Health Insurance Research Database and survival data from the National Death Registry.

RESULTS

In total, 1497 patients who were older than 20 years and had newly diagnosed CLL/SLL during 2006-2015 were identified. The age-standardized incidence rates of CLL/SLL (0.36 per 100 000 persons in 2006, and 0.54 in 2015) increased during the 10-year period. The sex ratio was ranged from 1.21 to 2.63 with male predominant during 2006 and 2015. For the analysis of treatment patterns (n = 1236), 72.8% patients received chemotherapies. The median duration between the diagnosis and start of treatments was 27 days, and monotherapy of chlorambucil, bendamustine or cyclophosphamide was the most common regimen in initial treatments. The median follow-up duration for the patients receiving therapies was 29.6 months, and 45.0% patients experienced relapse or refractory. In patients with relapse/refractory CLL/SLL, 34.1% received rituximab-containing chemotherapies. Three hundred and ninety-nine (32.3%) patients received intensive treatments, and 175 (43.9%) of them received rituximab-containing chemotherapies. The 5-year overall survival (OS) rate was 61%, and age was an important prognostic factor for CLL/SLL patients.

CONCLUSIONS

This study is the first population-based study in Asia and provides comprehensive evidence of epidemiology, treatment patterns and survivals of CLL/SLL in an Asian population.

Definition, Epidemiology, Pathophysiology, and Essential Criteria for Diagnosis of Pediatric Chronic Myeloid Leukemia

Simple Summary

The low incidence (1:1,000,000) of chronic myeloid leukemia (CML) in the first two decades of life presents an obstacle to accumulation of pediatric experience and knowledge on this leukemia. Biological features of CML are shared but also differing between adult and pediatric patients. This review aims; (i) to define the disease based on an unified terminology, (ii) to list the diseases to be considered as a differential diagnosis in children, (iii) to outlines the morphological, histopathological and immuno-phenotypical findings of pediatric CML, (iv) to illustrate rare but classical complications resulting from high white cell and platelet counts at diagnosis, and (v) to recommend a uniform approach for the diagnostic procedures to be applied. Evidently, only a clear detailed picture of all relevant features can lay the basis for standardized treatment approaches.

Abstract

Depending on the analytical tool applied, the hallmarks of chronic myeloid leukemia (CML) are the Philadelphia Chromosome and the resulting mRNA fusion transcript BCR-ABL1. With an incidence of 1 per 1 million of children this malignancy is very rare in the first 20 years of life. This article aims to; (i) define the disease based on the WHO nomenclature, the appropriate ICD 11 code and to unify the terminology, (ii) delineate features of epidemiology, etiology, and pathophysiology that are shared, but also differing between adult and pediatric patients with CML, (iii) give a short summary on the diseases to be considered as a differential diagnosis of pediatric CML, (iv) to describe the morphological, histopathological and immunophenotypical findings of CML in pediatric patients, (v) illustrate rare but classical complications resulting from rheological problems observed at diagnosis, (vi) list essential and desirable diagnostic criteria, which hopefully in the future will help to unify the attempts when approaching this rare pediatric malignancy.

Clinical characteristics of chronic lymphocytic leukemia occurring in chornobyl cleanup workers

The recently demonstrated radiation-induction of chronic lymphocytic leukemia (CLL) raises the question as to whether the amount of radiation exposure influences any of the clinical characteristics of the disease. We evaluated the relationship between bone marrow radiation doses and clinical characteristics and survival of 79 CLL cases diagnosed during 1986-2006 in a cohort of 110 645 male workers who participated in the cleanup work of the Chornobyl nuclear accident in Ukraine in 1986. All diagnoses were confirmed by an independent International Hematology Panel. Patients were followed up to the date of death or end of follow-up on 31 October 2010. The median age at diagnosis was 57 years. Median bone marrow dose was 22.6 milligray (mGy) and was not associated with time between exposure and clinical diagnosis of CLL (latent period), age, peripheral blood lymphocyte count or clinical stage of disease in univariate and multivariate analyses. Latent period was significantly shorter among those older at first exposure, smokers and those with higher frequency of visits to the doctor prior to diagnosis. A significant increase in the risk of death with increasing radiation dose was observed (p = 0.03, hazard ratio = 2.38, 95% confidence interval: 1.11,5.08 comparing those with doses ≥22 mGy to doses <22 mGy). After adjustment for radiation dose, survival of CLL cases was significantly shorter among those with younger age at first exposure, higher peripheral blood lymphocyte count, more advanced clinical stage of disease and older age at diagnosis (all p < 0.05). This is the first study to examine association between bone marrow radiation doses from the Chornobyl accident and clinical manifestations of the CLL in Chornobyl cleanup workers. The current study provides new evidence on the association of radiation dose and younger age at first radiation exposure at Chornobyl with shorter survival after diagnosis. Future studies are necessary with more cases in order to improve the statistical power of these analyses and to determine their significance. Copyright © 2016 John Wiley & Sons, Ltd.

The Ukrainian-American study of leukemia and related disorders among Chornobyl cleanup workers from Ukraine: III. Radiation risks

Leukemia is one of the cancers most susceptible to induction by ionizing radiation, but the effects of lower doses delivered over time have not been quantified adequately. After the Chornobyl (Chernobyl) accident in Ukraine in April 1986, several hundred thousand workers who were involved in cleaning up the site and its surroundings received fractionated exposure, primarily from external gamma radiation. To increase our understanding of the role of protracted low-dose radiation exposure in the etiology of leukemia, we conducted a nested case-control study of leukemia in a cohort of cleanup workers identified from the Chornobyl State Registry of Ukraine. The analysis is based on 71 cases of histologically confirmed leukemia diagnosed in 1986-2000 and 501 age- and residence-matched controls selected from the same cohort. Study subjects or their proxies were interviewed about their cleanup activities and other relevant factors. Individual bone marrow radiation doses were estimated by the RADRUE dose reconstruction method (mean dose = 76.4 mGy, SD = 213.4). We used conditional logistic regression to estimate leukemia risks. The excess relative risk (ERR) of total leukemia was 3.44 per Gy [95% confidence interval (CI) 0.47-9.78, P < 0.01]. The dose response was linear and did not differ significantly by calendar period of first work in the 30-km Chornobyl zone, duration or type of work. We found a similar dose-response relationship for chronic and non-chronic lymphocytic leukemia [ERR = 4.09 per Gy (95% CI < 0-14.41) and 2.73 per Gy (95% CI < 0-13.50), respectively]. To further clarify these issues, we are extending the case-control study to ascertain cases for another 6 years (2001-2006).

Chronic lymphocytic leukaemia: an overview of aetiology in light of recent developments in classification and pathogenesis

This overview of the epidemiology of chronic lymphocytic leukaemia (CLL) summarizes the evolution of classification and coding systems and describes the intersection of pathogenesis and aetiology. The role of the putative precursor to CLL, monoclonal B-cell lymphocytosis (MBL), is considered, and ideas for future investigations of the MBL-CLL relationship are outlined. We discuss the epidemiology of CLL, focusing on descriptive patterns and methodological considerations. Postulated risk factors are reviewed including the role of ionizing and non-ionizing radiation, occupational and environmental chemical exposures, medical conditions and treatments, and lifestyle and genetic factors. We conclude by raising key questions that need to be addressed to advance our understanding of CLL aetiology. Recommendations for future epidemiological studies are given, including the standardization of reporting of CLL across cancer registries, the clarification of the natural history of MBL, and the circumvention of the methodological shortcomings of prior epidemiological investigations in relation to radiation, chemical exposures and infectious agents.

Chronic lymphocytic leukaemia and small lymphocytic lymphoma: overview of the descriptive epidemiology

The 2001 World Health Organization classification scheme considers B-cell chronic lymphocytic leukaemia (CLL) and small lymphocytic lymphoma (SLL) in an aggregate category (CLL/SLL) because of shared clinicopathological features. We have estimated age-adjusted incidence rates (IRs) of CLL and SLL in the population-based Surveillance, Epidemiology and End Results Program in the United States to analyse patterns of CLL and SLL separately and jointly. Age-standardized to the 2000 US population, overall IRs were 3.83 per 100 000 person-years for CLL (n = 15 676) and 1.31 for SLL (n = 5382) during 1993-2004. Incidence of the combined entity, CLL/SLL, was 90% higher among males compared to females, and the male:female IR ratio was significantly higher for CLL (1.98) than for SLL (1.67). CLL/SLL IRs were 25% and 77% lower among Blacks and Asian/Pacific Islanders, respectively, compared to Whites. A significant reporting delay was evident for CLL but not for SLL, so that CLL/SLL temporal trends must be interpreted cautiously. CLL and SLL IRs increased exponentially with age among all gender/race groups, with CLL IRs increasing more steeply with advancing age than SLL. Avenues of future research include assessment of delayed- and under-reporting to cancer registries and exploration of race, gender, and age effects in epidemiological studies.

Chronic lymphocytic leukemia radiogenicity: a systematic review

OBJECTIVE

Chronic lymphocytic leukemia (CLL) is generally considered to be non-radiogenic and is excluded from several programs that compensate workers for illnesses resulting from occupational exposures. Questions about whether this exclusion is justified prompted a Congressional mandate to the National Institute for Occupational Safety and Health (NIOSH) to, further, examine the radiogenicity of CLL. This study revisits the question of CLL radiogenicity by examining epidemiologic evidence from occupationally and medically-exposed populations.

METHODS

A systematic review of radiation-exposed cohorts was conducted to investigate the association between radiation and CLL. Exploratory power calculations for a pooled occupational study were performed to examine the feasibility of assessing CLL radiogenicity epidemiologically.

RESULTS

There is a bias against reporting CLL results, because of the disease's presumed non-radiogenicity. In medical cohort studies that provide risk estimates for CLL, risk is elevated, though non-significantly, in almost all studies with more than 15 years average follow-up. The results of occupational studies are less consistent.

CONCLUSIONS

Studies with adequate follow-up time and power are needed to better understand CLL radiogenicity. Power analyses show that a pooled study might detect risk on the order of radiation induced non-CLL leukemia, but is unlikely to detect smaller risks.

Lymphoma incidence patterns by WHO subtype in the United States, 1992-2001

Because the causes of most lymphoid neoplasms remain unknown, comparison of incidence patterns by disease subtype may provide critical clues for future etiologic investigations. We therefore conducted a comprehensive assessment of 114,548 lymphoid neoplasms diagnosed during 1992-2001 in 12 Surveillance, Epidemiology, and End Results (SEER) registries according to the internationally recognized World Health Organization (WHO) lymphoma classification introduced in 2001. Cases coded in International Classification of Diseases for Oncology, Second Edition (ICD-O-2), were converted to ICD-O-3 for WHO subtype assignment. Age-specific and age-adjusted rates were compared by sex and race (white, black, Asian). Age-adjusted trends in incidence were estimated by sex and race using weighted least squares log-linear regression. Diverse incidence patterns and trends were observed by lymphoid neoplasm subtype and population. In the elderly (75 years or older), rates of diffuse large B-cell lymphoma (DLBCL) and follicular lymphoma increased 1.4% and 1.8% per year, respectively, whereas rates of chronic lymphocytic leukemia/small lymphocytic lymphoma (CLL/SLL) declined 2.1% per year. Although whites bear the highest incidence burden for most lymphoid neoplasm subtypes, most notably for hairy cell leukemia and follicular lymphoma, black predominance was observed for plasma cell and T-cell neoplasms. Asians have considerably lower rates than whites and blacks for CLL/SLL and Hodgkin lymphoma. We conclude that the striking differences in incidence patterns by histologic subtype strongly suggest that there is etiologic heterogeneity among lymphoid neoplasms and support the pursuit of epidemiologic analysis by subtype.

Ionizing radiation and chronic lymphocytic leukemia

The U.S. government recently implemented rules for awarding compensation to individuals with cancer who were exposed to ionizing radiation while working in the nuclear weapons complex. Under these rules, chronic lymphocytic leukemia (CLL) is considered to be a nonradiogenic form of cancer. In other words, workers who develop CLL automatically have their compensation claim rejected because the compensation rules hold that the risk of radiation-induced CLL is zero. In this article we review molecular, clinical, and epidemiologic evidence regarding the radiogenicity of CLL. We note that current understanding of radiation-induced tumorigenesis and the etiology of lymphatic neoplasia provides a strong mechanistic basis for expecting that ionizing radiation exposure increases CLL risk. The clinical characteristics of CLL, including prolonged latency and morbidity periods and a low case fatality rate, make it relatively difficult to evaluate associations between ionizing radiation and CLL risk via epidemiologic methods. The epidemiologic evidence of association between external exposure to ionizing radiation and CLL is weak. However, epidemiologic findings are consistent with a hypothesis of elevated CLL mortality risk after a latency and morbidity period that spans several decades. Our findings in this review suggest that there is not a persuasive basis for the conclusion that CLL is a nonradiogenic form of cancer.

Chronic myeloid leukemia: pathophysiology, diagnostic parameters, and current treatment concepts

Chronic myeloid leukemia (CML) is a stem cell disease characterized by excessive accumulation of clonal myeloid (precursor) cells in hematopoietic tissues. CML cells display the translocation t(9; 22) that creates the bcr/abl oncogene. The respective oncoprotein (= BCR/ABL) exhibits constitutive tyrosine kinase activity and promotes growth and survival in CML cells. Clinically, CML can be divided into three phases: the chronic phase (CP), the accelerated phase (AP), and the blast phase (BP) that resembles acute leukemia. Progression to AP and BP is associated with occurrence of additional genetic defects that cooperate with bcr/abl in leukemogenesis and lead to resistance against antileukemic drugs. The prognosis in CML is variable depending on the phase of disease, age, and response to therapy. The only curative approach available to date is stem cell transplantation. For those who cannot be transplanted, the BCR/ABL tyrosine kinase inhibitor STI571 (Glivec, Imatinib), interferon-alpha (with or without ARAC), or other cytoreductive drugs are prescribed. Currently available data show that STI571 is a superior compound compared to other drugs in producing complete cytogenetic and molecular responses. However, despite superior initial data and high expectations for an effect on survival, long term results are not available so far, and resistance against STI571 has been reported. Forthcoming strategies are therefore attempting to prevent or counteract STI571 resistance by co-administration of other antileukemic drugs. Whether these strategies will lead to curative drug therapy in CML in the future remains at present unknown.

Molecular abnormalities in B-cell chronic lymphocytic leukaemia

Chronic lymphocytic leukaemia is the commonest adult leukaemia, however the pathogenesis is largely unknown. Since the 1980s specific chromosomal abnormalities have been identified, of which the commonest are deletions of chromosomes 6q, 11q23, 13q14 and 17q13 and trisomy 12. The search for the responsible oncogenes at these sites has proved to be extremely frustrating. There are many oncogenes at 11q23 but the exact gene(s) responsible have yet to be identified. Germline abnormalities of the ATM gene occur in about 18% of patients compared to a normal population carriage of 0.5% but not all studies agree that ATM is the gene responsible. Unfortunately, despite the identification of various minimally deleted regions and the full sequencing of 13q14 no oncogenes have been identified. All original studies suggested the presence of a autosomally recessive tumour suppressor gene at this site but more recent studies suggest this may not be the case and the pathogenesis is more complex than first thought. Similarly, no genes have been identified at 6q or on chromosome 12. We know that the p53 tumour suppressor gene at 17p13 is an important prognostic indicator but it occurs in a minority of patients (about 15%), usually in patients with advanced disease, and therefore probably is not of aetiological importance.

VH gene usage by family members affected with chronic lymphocytic leukaemia

The excess risk of chronic lymphocytic leukaemia (CLL) in the first-degree relatives of affected patients suggests that familial CLL might constitute a useful model to study the pathogenesis of this disease, as has been demonstrated in numerous other neoplastic disorders. Previous studies have shown non-random utilization of immunoglobulin genes in CLL, some germline in sequence and others containing numerous somatic mutations. To investigate whether familial cases of CLL exhibit similarities in the composition of the B-cell receptor repertoire to the pattern expressed by CLL patients as a whole, we have studied 25 CLL patients belonging to 12 different families (four French and eight Italian), each of which contained at least two affected members. Among familial cases, VH gene segment utilization proved non-random and diverged from the frequencies previously reported among unrelated patients with CLL. Specifically, although the 4-34 and 5-51 gene segments were found repeatedly, the 1-69 and 4-39 gene segments were used sparingly and the 3-23 gene segment presented with increased frequency. Following the pattern detected in studies of unrelated patients, the single 1-69 expressing CLL contained an unmutated H chain sequence and included a long HCDR3 interval. In contrast, 3-23 containing H chains all used JH4, retained at most 93% homology with germline sequence, and included only short HCDR3 intervals. The vast majority of the CLL variable domains contained a high degree of somatic mutation and exhibited an excess of replacement mutations in the CDR intervals. These findings suggest that familial CLL cases may preferentially derive from B-cell progenitors that have responded to antigen.

Analysis of the B-Cell Receptor B29 (CD79b) Gene in Familial Chronic Lymphocytic Leukemia

The B-cell antigen receptor (BCR) comprises membrane Igs (mIgs) and a heterodimer of Ig (CD79a) and Igβ (CD79b) transmembrane proteins, encoded by the mb-1 and B29 genes, respectively. These accessory proteins are required for surface expression of mIg and BCR signaling. B cells from chronic lymphocytic leukemia (B-CLL) frequently express low to undetectable surface Ig, as well as CD79b protein. Recent work described genetic aberrations affecting B29 expression and/or function in B-CLL. Because the prevalence of CLL is increased among first degree relatives, we analyzed the B29 gene in 10 families including 2 affected members each. A few silent or replacement mutations were observed at the genomic level, which never lead to truncated CD79b protein. Both members of the same family did not harbor the same mutations. However, a single silent base change in the B29 extracellular domain, corresponding to a polymorphism, was detected on 1 allele of most patients. These results indicate that the few mutations observed in the B29 gene in these patients do not induce structural abnormalities of the CD79b protein and thus do not account for its low surface expression in B-CLL. Furthermore, genetic factors were not implicated, because identical mutations were not observed among 2 members of the same family.

Mortality experience of a young petrochemical industry cohort. 1979-1992 follow-up study of US-based employees

This retrospective study examines the mortality patterns of a relatively young cohort of 81,746 former and current petrochemical company employees. Standardized mortality ratios (SMR) for 1979 through 1992 are generally from about unity to well below unity for major causes and numerous specific causes of death studied by gender/race/job subgroups. Findings of note include a SMR (based on incidence rates) of 1.94 (95% confidence interval [CI], 1.04 to 3.33) for mesothelioma, and a SMR of 1.81 (95% CI, 0.90 to 3.24) for chronic lymphocytic leukemia, both among males hired before 1960. All male semiskilled operatives have a 1.6-fold increase (95% CI, 1.07 to 2.29) in motor vehicle accident deaths, with declining rates since the mid-1980s. The overall SMR for acquired immunodeficiency syndrome (AIDS) is at unity (69 deaths), with excesses in technician and office worker subgroups. Four decedents with lymphoma (code 202.8 in 9th revision ICD) had AIDS as a secondary cause of death, suggesting the need to examine secondary causes when studying lymphopoietic conditions. This routine surveillance activity provides leads regarding the presence or absence of excess mortality risk.

Genes and chromosomes in chronic B-cell leukemia

Cytogenetic analysis of patients with chronic B-cell leukemia (B-CLL) indicates that 50% have chromosome abnormalities, while fluorescence in situ hybridization (FISH) and molecular techniques reveal an even higher incidence. Trisomy 12 and deletions or translocation of chromosome 13q14 are the most common abnormalities, but in neither case has the gene or genes involved in the abnormalities been identified. Combined FISH and immunophenotyping studies suggest that both abnormalities are secondary events in B-CLL. Other recurring chromosome abnormalities include 6q-, 11q- and 12p-, but the genes involved in these abnormalities have not been identified. Involvement of the BCL1, BCL2, and BCL3 genes has been reported, but the numbers are low and the cases tend to be atypical. Trisomy 12 in association with complex karyotypic abnormalities is associated with a poor prognosis, and FISH studies show a strong correlation between trisomy 12, atypical morphology, and advanced disease. Ten to 15% of patients have mutations of p53 which is associated with advanced disease, resistance to treatment, and poor survival.

Bilateral fracture of the mandible in chronic lymphocytic leukaemia. Case report

The development of osteolytic bone lesions in patients with chronic lymphocytic leukaemia (CLL) is extremely rare and has not been reported to involve the mandible. A case of bilateral pathologic fracture of the mandible extensively involved with multiple bony deposits of CLL is reported.

A greater incidence of complex translocations in myeloid leukemias than in lymphomas and lymphoid leukemias associated with IGH rearrangement

We have shown that the incidence of complex translocations is approximately the same in chronic myeloid leukemia, characterized by the t(9;22)(q34;q11), and in acute myeloid leukemias, characterized by the t(15;17)(q22;q11) or t(8;21)(q22;q22). This incidence is almost threefold greater than the incidence of complex translocations in lymphomas and lymphoid leukemias characterized by the t(8;14)(q24;q32) or t(14;18)(q32;q21). The genomic recombination, which gives rise to the translocations in lymphoid cells, results mostly from errors of IGH gene rearrangement. Genomic recombination underlying myeloid leukemias has a different cause, and a clue to this may lie in the greater incidence of complex chromosome rearrangements.

Survival of young patients with chronic lymphocytic leukemia failing fludarabine therapy: a basis for the use of myeloablative therapies

We examined the survival of 91 young patients (< or = 55 years) with chronic lymphocytic leukemia from the time of failure of fludarabine therapy, in an attempt to identify those with a poor outcome who may benefit from investigative dose-intensive therapies. The median survival of patients unresponsive to fludarabine (n = 42) was 48 weeks, and only 11% responded to subsequent therapies. The median survival of patients relapsing following a fludarabine-induced remission (n = 49) was 87 weeks, and 83% of those who had received fludarabine as their first therapy (n = 14) responded to further fludarabine-containing therapies, with 60% alive at four years. Only 7% of those relapsing patients who had received fludarabine as salvage therapy (n = 35) responded to subsequent therapies (median survival 72 weeks). The poor outlook for these patients justifies the consideration of innovative dose-intensive therapies, such as bone marrow transplantation, with their attendant risk of toxicity.

Chronic lymphocytic leukemia: present status

Chronic lymphocytic leukemia (CLL) is the form of leukemia which occurs most frequently in Western countries. Its etiology is unknown, and no relationship with viruses or genes has been demonstrated. Epidemiological data suggest that genetic and ambiental factors might be of some significance. Clinical features of CLL are due to the accumulation of leukemic cells in bone marrow and lymphoid organs as well as the immune disturbances that accompany the disease. The prognosis of patients with CLL varies. Treatment is usually indicated by the risk of the individual patient, which is clearly reflected by the stage of the disease. In the early stage (Binet A, Rai O) it is reasonable to defer therapy until disease progression is observed. By contrast, because their median survival is less than five years, patients with more advanced stages require therapy. For almost 50 years, no major advances in the management of CLL, which has revolved around the use of alkylating agents, have been made. In recent years, the therapeutic approach in patients with CLL has changed as a result of the introduction of combination chemotherapy regimens and, in particular, purine analogues. The latter are already the treatment of choice for patients not responding to standard therapies, and their role as front-line therapy is being investigated. Bone marrow transplants are also being increasingly used. It is to be hoped that in years to come the outcome of patients with CLL will be improved by these advances.

Incidence of leukemia in Olmsted County, Minnesota, 1975 through 1989

OBJECTIVE

To determine the incidence of leukemia in Olmsted County, Minnesota, for a recent 15-year period and to compare the data with reported rates for the previous 40 years.

DESIGN

We conducted a population study of leukemia diagnosed between 1975 and 1989 in residents of Olmsted County by review of medical records identified through diagnostic indexes, death certificates, autopsy files, and histologic preparations.

MATERIAL AND METHODS

Diagnoses of leukemia were categorized into various subtypes, and age- and sex-specific incidence rates were calculated for leukemia as a whole and for each subtype. In addition, incidence rates were age- and sex-adjusted to the 1970 US white population for comparison with earlier published rates. Age and annual trends as well as sex differences were assessed with the generalized linear interactive model approach.

RESULTS

During 1975 through 1989, the mean annual incidence rate for leukemia was 12.3 per 100,000 population in Olmsted County. When adjusted for age and sex, the rate per 100,000 was 13.6, in comparison with a similarly adjusted rate of 11.8 for the previous decade (1965 through 1974). The rates for chronic myelogenous leukemia and acute lymphocytic leukemia remained stable throughout the entire study period; however, rates for acute myelogenous leukemia and chronic lymphocytic leukemia increased, most prominently in patients 50 years of age or older. This increased rate occurred in both males and females, but the incidence rates for both subtypes began increasing earlier for males than for females.

CONCLUSION

Although we cannot rule out an actual increase in incidence rates for these types of leukemia in the elderly population, we believe that the increase in persons older than 50 years of age reflects social change in improved health care and its better utilization by elderly persons, as well as the ability to diagnose leukemia earlier than in the past.

Incidence of chronic lymphocytic leukemia in Olmsted County, Minnesota, 1935 through 1989, with emphasis on changes in initial stage at diagnosis

OBJECTIVE

To determine whether the stage at the time of diagnosis of chronic lymphocytic leukemia (CLL) had changed during a 55-year period.

DESIGN

We conducted a study of the cohort of residents of Olmsted County, Minnesota, who had been diagnosed as having CLL during the period from 1935 through 1989.

MATERIAL AND METHODS

By analysis of medical records, patients with CLL were characterized by Rai stage, absolute lymphocyte count, age at diagnosis, need for therapy, and reported cause of death in nonsurvivors. Trends for these variables were analyzed by decade throughout the study period.

RESULTS

The overall annual incidence rate of CLL per 100,000 population in Olmsted County increased from 2.6 in the 1935 through 1944 period to 5.4 in the 1975 through 1984 period; however, the increasing rate was found only for those 50 years of age or older and was especially dramatic for those 75 years old or older. Analysis of Rai stage over time demonstrated an increase in the proportion of cases diagnosed as Rai stage 0. In addition, the median absolute lymphocyte count decreased, the median time to initiation of therapy increased, and the median age of patients with Rai stage 0 CLL at the time of diagnosis increased over time. Overall, 54% of patients had received therapy for CLL by the time of last follow-up. Among the nonsurvivors, CLL was documented as the underlying or a contributing cause of death in 69%.

CONCLUSION

The overall increase in CLL was thought to be due to enhanced methods of early diagnosis and improved health care for the elderly population. Thus, artifact may best explain the observed trend, although we cannot exclude the possibility of an actual increase in incidence rates over time.

Japanese B cell chronic lymphocytic leukaemia: a cytogenetic and molecular biological study

Clinical, cytogenetic, and molecular genetic studies were performed to clarify the pathophysiology of Japanese B cell chronic lymphocytic leukaemia (B-CLL), since the incidence of B-CLL in Japan is significantly lower than in western countries. The clinical and laboratory features of 55 Japanese patients with B-CLL in this study did not differ from those of Americans or Europeans with B-CLL. In the chromosome analyses, suitable metaphases with good band quality were obtained from 48 patients (87.2%), of whom 22 patients (45.8%) showed clonal chromosome aberrations and 14 (29.2%) had non-clonal aberrations. Trisomy 12 and abnormalities of 14q and 13q were found in four (18.2%), two (9.1%) and six patients (27.2%), respectively. There were no particular chromosome abnormalities or specific breakpoints in Japanese B-CLL. However, complex karyotype was found in higher incidence than in western countries. In the Southern blot analyses, rearranged band patterns were observed in the major breakpoint region (mbr) of the bcl-2 gene in one case, in the 5'-breakpoint region (5'-bcl-2) in two, and bcl-3 in one. Of the two patients with 5'-bcl-2 rearrangements, one had a normal karyotype and the other had t(2;18)(p12;q21). The incidence of rearrangements of the bcl-1, bcl-2 and bcl-3 genes in Japanese B-CLL was similar to that in western countries. These findings suggest that the biological characteristics of B-CLL in Japan are almost the same as those in western countries, although the incidence of B-CLL in Japan is quite different; this may be related to racial differences, which seem to be an important factor in the development of B-CLL.