Role of immune stimulation in the etiology of multiple myeloma: a case control study

Risk of multiple myeloma in rheumatoid arthritis: a meta-analysis of case-control and cohort studies

Objectives

multiple myeloma is a malignant neoplasm of plasma cells mainly affecting elderly patients. Despite the wealth of information available on therapeutic strategies, the etiology and pathogenesis of myeloma remain unclear. In the current study, a meta-analysis was conducted to assess the possible association between rheumatoid arthritis and myeloma.

Methods

a literature search was conducted with PubMed, EMBASE and Web of Science for relevant studies published by December 25, 2013. Additionally, we searched annual meeting abstracts of the American Society of Hematology from 2004 to 2013. Only original studies that investigated the association between rheumatoid arthritis and myeloma were included. In total, 8 case-control and 10 cohort studies were identified for analysis.

Results

the meta-estimate of the association between rheumatoid arthritis and myeloma was 1.14 (95% CI, 0.97–1.33) overall, with significant heterogeneity among studies. The relationship between myeloma and other autoimmune diseases was additionally examined from available data. Our results showed that myeloma risk is increased 1.31 to 1.65-fold in pernicious anemia and 1.36 to 2.30-fold in ankylosing spondylitis patients.

Conclusion

Rheumatoid arthritis does not appear to alter the risk of myeloma, while between-study heterogeneity analyses suggest caution in the interpretation of results. Pernicious anemia and ankylosing spondylitis may be potential risk factors for myeloma development. Future large-scale epidemiological studies with reliable exposure biomarkers are necessary to establish the possible contribution of autoimmune disorders to multiple myeloma.

Epidemiology of the plasma-cell disorders

This review of the plasma-cell disorders begins with the definition of monoclonal gammopathy of undetermined significance (MGUS). The prevalence of MGUS in white and black populations is described. MGUS is a common finding in the medical practice of all physicians, and thus it is important to both the patient and the physician to determine whether the monoclonal protein remains stable or progresses to multiple myeloma (MM), Waldenström's macroglobulinemia (WM), primary systemic amyloidosis (AL), or a related disorder. The long-term (almost 40 years) follow-up data of 241 patients in the Mayo Clinic population is provided. In a large study of 1384 patients with MGUS from southeastern Minnesota, the risk of progression to MM, WM, AL, or other disorders was approximately 1% per year. Risk factors for progression are provided. The incidence of MM in Olmsted County, Minnesota, remained stable for the 56-year span 1945-2001. The apparent increase in incidence and mortality rates among patients with MM in many studies is due to improved case ascertainment, especially among the elderly. The incidence and mortality rates of MM in the United States and other countries are presented. The major emphasis is on the cause of MM, which is unclear. Exposure to radiation from atomic bombs, therapeutic and diagnostic radiation, and in workers in the nuclear industry field are addressed. Many studies involving agricultural occupations, exposure to benzene, petroleum products, and engine exhaust and other industrial exposures are discussed. Tobacco use, obesity, diet, and alcohol ingestion are all possible causes of MM. Clusters of MM have been noted. Multiple cases of MM have been found in first-degree relatives.

Multiple myeloma: A review of the epidemiologic literature

Multiple myeloma, a neoplasm of plasma cells, accounts for approximately approximately 15% of lymphatohematopoietic cancers (LHC) and 2% of all cancers in the US. Incidence rates increase with age, particularly after age 40, and are higher in men, particularly African American men. The etiology is unknown with no established lifestyle, occupational or environmental risk factors. Although several factors have been implicated as potentially etiologic, findings are inconsistent. We reviewed epidemiologic studies that evaluated lifestyle, dietary, occupational and environmental factors; immune function, family history and genetic factors; and the hypothesized precursor, monoclonal gammopathies of undetermined significance (MGUS). Because multiple myeloma is an uncommon disease, etiologic assessments can be difficult because of small numbers of cases in occupational cohort studies, and few subjects reporting exposure to specific agents in case-control studies. Elevated risks have been reported consistently among persons with a positive family history of LHC. A few studies have reported a relationship between obesity and multiple myeloma, and this may be a promising area of research. Factors underlying higher incidence rates of multiple myeloma in African Americans are not understood. The progression from MGUS to multiple myeloma has been reported in several studies; however, there are no established risk factors for MGUS. To improve our understanding of the causes of multiple myeloma, future research efforts should seek the causes of MGUS. More research is also needed on the genetic factors of multiple myeloma, given the strong familial clustering of the disease.

Racial differences in the prevalence of monoclonal gammopathy in a community-based sample of the elderly

PURPOSE

To determine if there is an increased prevalence of monoclonal gammopathy in elderly blacks compared with whites, analogous to the difference in incidence of multiple myeloma reported for the two racial groups and to confirm age and gender relationships.

PATIENTS AND METHODS

Subjects were from the Duke Established Populations for the Epidemiologic Study of the Elderly, selected on the basis of stratified random household sampling. Blacks were oversampled to allow for increased statistical precision in racial comparisons. In all, 1,732 subjects (aged > 70 years) consented to blood drawing and constitute the sample for this study. Monoclonal immunoglobulins were determined by agarose gel electrophoresis and immunofixation.

RESULTS

One hundred six subjects (6.1%) had a monoclonal gammopathy. There was a greater than twofold difference in prevalence between blacks (8.4%) and whites (3.8%) (P < 0.001); monoclonal gammopathy prevalence increased with age, and was greater in men than women. Those with monoclonal gammopathy did not differ from those without in socioeconomic status, urban/rural residence, or education. The presence of monoclonal gammopathy was not associated with any specific diseases nor with impaired functional status. There was a slight increase in serum creatinine levels and decrease in hemoglobin and albumin levels in patients with monoclonal gammopathy, but no difference in interleukin-6 (IL-6) levels. Moreover, IL-6 levels were not correlated significantly with the level of monoclonal protein.

CONCLUSION

Prevalence of monoclonal gammopathy is significantly greater among blacks than whites in a community-based sample, in approximately the same ratio that multiple myeloma has been reported in the two groups. Given the absence of correlation with environmental factors, there may be a biological racial difference in susceptibility to an early event in the carcinogenic process leading to multiple myeloma.

Risk of monoclonal gammopathy of undetermined significance: a case-referent study

A retrospective study was conducted in 285 cases of monoclonal gammopathy of undetermined significance (MGUS) and in 570 sex- and age-matched hospital controls in order to investigate the possible association between socioeconomic status, residence, alcohol and tobacco habits, occupation, occupational exposure to toxic substances, chronic antigenic stimulation, and risk of MGUS. Significant associations with the risk of MGUS were found for farmers (P < 0.005) and for workers in industry (P < 0.025). Occupational exposure to asbestos, fertilizers, mineral oils and petroleum, paints and related products, pesticides, and radiation was significantly (P < 0.05) associated with an increase in risk of MGUS. Chronic immune-stimulating conditions, when considered as a group, presented a significant (P < 0.025) association with the risk of MGUS, but no specific disease has been found to be significantly associated. These data are in agreement with the previous reports on multiple myeloma, suggesting that these factors may play an important role in the development of monoclonal gammopathies. However, these findings need to be confirmed in prospective larger population-based studies.

Multiple myeloma among blacks and whites in the United States: the role of chronic antigenic stimulation

Multiple myeloma (MM) is twice as common among Blacks than Whites in the United States. The reasons for this racial disparity are unknown, and the etiology of this cancer, in general, is poorly understood. Repeated or chronic antigenic stimulation (CAS) of the immune system has been suggested as a risk factor. Previous case-control studies have reported inconsistent CAS associations based on evaluations of individual and biologic categories of medical conditions. Interview data from 573 cases and 2,131 population-based controls were used to investigate further the CAS hypothesis using an immunologically based approach, and to determine whether CAS accounts for the excess of myeloma among Blacks. Over 50 medical conditions were grouped into biologically and immunologically related categories, and B-cell- and T-cell-mediated response groups. Except for urinary tract infections among Black men (odds ratio [OR] = 2.0), no significantly increased risks of MM were observed. However, there was a suggestion of increased risk among Blacks with an increased exposure to anaphylactic conditions. Analysis by immunoglobulin type revealed significantly elevated risks of IgG myeloma with eczema (OR = 2.1), the biologic category 'allergic conditions' (OR = 1.6), and the immunologic category 'anaphylaxis response' (OR = 1.6) among Whites, with Blacks having slightly lower risks. Our findings do not support a causal relationship between CAS and MM, nor do they explain the higher incidence among Blacks.

Antigenic stimulation and multiple myeloma. A prospective study

BACKGROUND

A causal relationship between antigenic conditions and multiple myeloma was suggested by case reports. Although controlled studies identified associations with individual conditions, they failed to give overall support to the hypothesis. Using a prospective cohort representative of the U.S. population, the authors hypothesized that immune-stimulating conditions are a risk factor for multiple myeloma.

METHODS

The First National Health and Nutrition Examination Survey cohort of 14,407 persons were interviewed from 1971 to 1975 by the National Center for Health Statistics. Vital status with cause of death and hospitalizations were ascertained from 1982 to 1985 and in 1986. From the initial questionnaire, four risk factors were constructed: allergies (asthma, hives, hay fever, food allergies, and other allergies); autoimmune conditions (arthritis, thyroid disease and/or medication, rheumatic fever, diabetes, pernicious anemia); chronic bacterial conditions (chronic bronchitis or emphysema, chronic cough, tuberculosis, ulcers); and inflammatory conditions (gout, gallstones, recurrent or chronic enteritis, pleurisy).

RESULTS

Eighteen multiple myeloma (MM) cases were documented. The rate ratio (RR) of MM increased as the number of reported inflammatory conditions increased (one condition, RR = 2.0, 95% confidence interval [CI] = 1.2-3.3; 2 or more conditions, RR = 4.3, 95% CI = 1.5-12.4). The RR of myeloma also increased (P = 0.0002) with time since start of inflammatory conditions (RR = 1.6 for every 10 years of exposure). When cases were restricted to those with more than five years of follow-up, myeloma risk increased with the number of inflammatory conditions (two conditions, RR = 4.6, 95% CI = 1.5-13.8).

CONCLUSIONS

Although the number of cases is small and exposure may be misclassified, the prospective nature of the study design strengthens the results of the study.

A comparative study of monoclonal gammopathies and immunoglobulin levels in Japanese and United States elderly

OBJECTIVE

To define the prevalence of monoclonal immunoglobulin (Ig) proteins and quantitative serum immunoglobulin levels in elderly Japanese in comparison with elderly Caucasians as possible factors related to the reported lower incidence of multiple myeloma in elderly Japanese than in elderly Caucasians.

DESIGN

Survey study

SETTING

Community Center in Yokohama, Japan and Retirement Community in the United States.

PARTICIPANTS

Convenience sample of community-dwelling elderly subjects (age 63-95) presenting for health screening examinations in each setting. Frozen serum samples were obtained from routine screening from 146 consecutive Japanese subjects and 111 US subjects.

INTERVENTION

None

MEASUREMENTS

Presence of monoclonal immunoglobulin protein determined by serum protein electrophoresis and immunofixation and quantitative Ig by laser nephelometry.

RESULTS

Four (2.7%) of the Japanese cohort had monoclonal gammopathies compared with 11 (10%) of the American cohort. Two of the monoclonal gammopathies were IgG Kappa and two were IgG Lambda. No cases of multiple monoclonal gammopathy were identified in the Japanese group, compared with 25% of the monoclonal gammopathies in the American group. The mean quantitative serum IgG level for the Japanese group was 1,685 +/- 520 mg/dL versus 1,118 +/- 402 mg/dL for the American group; mean quantitative IgA levels were 283 +/- 116 mg/dL versus 226 +/- 116 mg/dL (P < 0.001). Albumin levels were normal in both populations, suggesting that there was not an increase in occult inflammatory disorders in the Japanese population.

CONCLUSION

The low prevalence of monoclonal gammopathy in elderly Japanese is consistent with the reported lower frequency of multiple myeloma. The reason for the higher quantitative immunoglobulin levels in this population is unclear. Further cross-cultural investigation is warranted to explore the genetic influences on altered immune regulation with aging.

Rheumatoid arthritis as a risk factor for multiple myeloma: a case-control study

This population-based case-control investigation was designed to study the importance of rheumatoid arthritis, other diseases and different types of treatment for the risk of developing multiple myeloma. In total, 275 cases with verified myeloma in northern Sweden were matched to as many control subjects. Information about different diseases, drug use, diagnostic X-ray investigations and radiotherapy was obtained through an extensive questionnaire mailed to all living subjects, i.e. cases and controls, and to the next of kin regarding deceased subjects. The study confirmed a suspected association with both rheumatic diseases in general and rheumatoid arthritis specifically. No other disease gave an increased risk for myeloma, but on the contrary, other diseases were in general more common among the controls. In accordance with this finding, use of medications and diagnostic X-ray investigations were also less common in cases than in controls. The study did, however, give some support to a recent finding that the number of X-ray investigations might be a risk factor for myeloma. Earlier radiotherapy on benign indications was more common in cases, whereas radiotherapy for malignant disease was more common among controls in this study.

Leukemia, lymphoma, and multiple myeloma following selected medical conditions

The role of selected prior medical conditions in the etiology of hematopoietic malignancies was examined in a case-control study of members of two regional branches of the Kaiser Permanente Medical Care Program (USA). Past history of chronic infectious, autoimmune, allergic, and musculoskeletal disorders was abstracted from medical records for leukemia (n = 299), non-Hodgkin's lymphoma (NHL, n = 100), and multiple myeloma (n = 175) cases and matched controls (n = 787). Little difference was found between cases and controls for most of the chronic conditions evaluated, including sinusitis, carbuncles, urinary tract infections, pelvic infections, herpes zoster, asthma, rheumatoid arthritis, psoriasis, bursitis, and gout. Only three statistically significant elevated risks were found, i.e., with combined disc disease myeloma among patients with prior eczema and disk and other musculoskeletal conditions, and NHL following tuberculosis. Only two of these associations showed consistent patterns by sex and geographic region (myeloma with eczema and with musculoskeletal conditions). While prior history of eczema and musculoskeletal conditions may slightly increase risk of myeloma, this study provided little if any support for an association of chronic infectious, autoimmune, allergic, and musculoskeletal conditions with subsequent occurrence of the leukemias or NHL. Additionally, these data did not support a role for chronic antigenic stimulation, as defined in previous epidemiologic studies, in the etiology of hematopoietic malignancies.

Current concepts on monoclonal gammopathies

This is a review of the monoclonal gammopathies, including a discussion of cause. The role of T lymphocytes and B lymphocytes is presented. The recognition of a monoclonal protein in the serum and urine is presented in detail. The frequency of benign and malignant monoclonal gammopathies is provided. A long-term follow-up of 241 patients with apparently benign monoclonal gammopathy is examined closely. In this series, multiple myeloma, macroglobulinaemia, amyloidosis, or related disorders developed in 22% of the 241 patients with long-term disease. The median duration from the recognition of the monoclonal protein until the development of serious disease was approximately eight to ten years. The differentiation of benign from malignant monoclonal gammopathies is examined in detail. The point is made that patients must be followed indefinitely because malignancy may develop more than 20 years later. The association of monoclonal gammopathies with other apparently unrelated diseases is discussed.

Interleukin-6 is a cofactor for the growth of myeloid cells from human bone marrow aspirates but does not affect the clonogenicity of myeloma cells in vitro

Several groups have claimed that IL-6 is a growth factor for human myeloma cells in vitro. Bone marrow aspirates from 30 patients at different stages of treatment with VAMP/high dose melphalan, were examined for myeloma colony formation (MY-CFUc) using a clonogenic assay in vitro. Myeloma cells from 16/30 patients produced MY-CFUc in our assay system, which uses heavily irradiated HL60 cells as an underlay in soft agar. These heavily irradiated cells were shown to be essential for the inhibition of granulocyte-macrophage colonies (GM-CFUc). The addition of recombinant human IL-6 (10 ng/plate) reduced the number of bone marrow samples which produced MY-CFUc from 16 to six. Furthermore, the addition of antibody to IL-6 (1 microgram/plate) failed to inhibit MY-CFUc from 6/7 samples. Conditioned medium from human peripheral blood mononuclear cells (PBMC-CM) contains approximately 2 ng/ml IL-6 and can be used to stimulate the growth and maintenance of the B9 murine IL-6 dependent hybridoma cell line. Recombinant human IL-6 supported the growth of B9 cells in a clonogenic assay and growth was inhibited by anti-IL-6 in the presence of rhIL-6 or PBMC-CM. Mononuclear cells from a second group of myeloma patients were cultured in soft agar in a mixture of PBMC-CM and fresh growth medium. Nine of the 10 samples produced myeloid colonies which consisted of granulocytes, monocytes and macrophages and the number of colonies was reduced by at least 50% in 6/8 samples when anti-IL-6 was added to the cultures. In no instance were MY-CFUc produced. Also, conditioned medium from the bladder carcinoma cell line 5637, which is used routinely as a source of granulocyte-macrophage colony stimulating factor (GM-CSF), contains approximately 4 ng/ml IL-6. Although rhIL-6 failed to stimulate GM-CFUc in the absence of other growth factors, addition of anti-IL-6 to cultures containing a suboptimal amount of 5637-CM reduced the number of colonies by 50%. These data provide evidence that IL-6 is a cofactor for the growth of myeloid precursors but does not affect the proliferation of human myeloma cells in vitro.

Chronic neutrophilic leukemia and multiple myeloma. An association with lambda light chain expression

Two patients with plasma cell dyscrasia and IgG lambda paraproteinemia in association with the rare disorder, chronic neutrophilic leukemia (CNL), are described. Cytogenetic studies excluded Philadelphia + chronic myeloid leukemia and molecular analysis of the breakpoint cluster region (bcr) revealed no evidence of clonal gene rearrangement. Nine similar cases of coexistent CNL and paraproteinemia have been identified in the literature and attention is drawn to the disproportionate excess of lambda light chain restriction in this subset of patients. Evidence supporting a clonal origin of CNL is considered and the nature of the relationship between the chronic myeloid expansion and the development of multiple myeloma is discussed.

Hospital versus random digit dialing controls in the elderly. Observations from two case-control studies

Finding an optimal source of controls is a major consideration in the design of case-control studies. While hospital patients can provide a relatively economical and convenient source of controls, hospital controls may have diseases independently associated with the exposures being studied. Results of a recent case-control study of multiple myeloma suggest that the problems of using hospital controls may be exacerbated in studies of diseases affecting the elderly, especially when considering risk factors which might be associated with chronic diseases. Apparently, the authors have encountered a modern analog of "Berkson's bias" in which cancer cases are referred to a tertiary care center for a single disease. On the other hand, noncancer patients who might serve as controls tend to be referred selectively if they have multiple diseases. This article reports some of the difficulties encountered in a case-control study whose mean case age was 63.4 years and suggests that community controls selected by random digit dialing may be preferable to hospital controls for hypothesis-generating case-control studies of diseases in the elderly.

Plasma cell dyscrasias: current status

This is a review of the current status of the monoclonal gammopathies (plasma cell dyscrasias). We begin with the recognition of a monoclonal protein in serum and urine. We briefly discuss the differential diagnosis of the monoclonal gammopathies. Clinical and laboratory findings as well as the management of multiple myeloma are addressed. Future approaches for the treatment of myeloma are provided. The variant forms of multiple myeloma, including smoldering myeloma, plasma cell leukemia, nonsecretory myeloma, IgD myeloma, osteosclerotic myeloma, solitary plasmacytoma of bone, and extramedullary plasmacytoma, are briefly reviewed. Diagnosis and treatment of Waldenström's macroglobulinemia are presented. The recognition and differential diagnosis of the heavy-chain diseases (gamma, alpha, and mu) are included. Monoclonal gammopathy of undetermined significance ("benign" monoclonal gammopathy) is presented in detail. Amyloidosis is not included in this review.