Additional ROC analysis supports the possibility that the H3K27 modification might predict more accurately in HCC than other prognostic indicators or markers. Despite extensive research efforts over the last two decades, the risk factors of MM remain to be established. Numerous case-control and cohort studies to date have suggested that several environmental factors may be associated with the risk of MM, such as ionizing radiation, benzene and agricultural occupation. The relationship between autoimmune disease and hematopoietic malignancies was initially postulated in 1964. However, the issue of whether autoimmune diseases increase the incidence of MM remains controversial. On the basis of animal models of MM, it is suggested that repeated antigenic stimulation of the immune system plays an important role in MM development. Similarly, the relationship between MM and autoimmune disease has been a long-term subject of investigation, but inconsistent results have been obtained to date. The main aim of this meta-analysis was to estimate the comparative risk of developing MM in RA patients versus the general population. Two additional goals were to explore the variation in the association of RA and MM among subgroups of interest and to investigate if there is an association between MM and other autoimmune diseases. Twenty-three casecontrol and cohort studies were included after full text assessment. Another two publications were incorporated after examining references from the extracted articles. Among the 25 studies, seven were subsequently excluded for overlap in case or cohort resources. Consequently, our meta-analysis consisted of eight case-control and ten cohort studies. All the studies MDV3100 published from 1982 to 2013 were performed in USA or Europe, except one case- control study from New Zealand. There was slight overlap in the patient populations of two studies from Finland. Landgren et al. limited the study subjects to women, while the groups of Pearce and Brown mainly focused on the role of prior autoimmune disorders in male MM. The NOS scores varied from 5 to 7 in all case-control studies, with the exception of the reported score of 3 by Landgren and co-workers as a result of unsatisfactory comparability. Since almost all the cohort studies used the expected cancer incidence calculated from national cancer rates as a comparison instead of the non-exposed cohort, NOS scores were relatively low, ranging from 4 to 5. In the eight case-control studies, OR was all obtained from the published articles or calculated from the numbers of cases and controls by RA. In four cohort studies, the SIRs and 95% CIs were estimated from the number of observed MM and expected MM incidence provided by authors, while others were directly extracted from the original article. Only three studies reported the type of treatment for RA before MM diagnosis.