Incidence of multiple myeloma in Kailuan cohort: A prospective community-based study in China

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Introduction

Multiple myeloma (MM) is malignant hematological disorder characterized by uncontrolled proliferation of clonal plasma cell in bone marrow and occurs mainly in the elderly. According to 2000–2017 Surveillance, Epidemiology, and End (SEER) database, MM incidence rates adjusted for age were confirmed to increase slightly from 6.0 per 100,000 individuals in 2000–7.5 per 100,000 individuals in 2017 in the United States (US) [1] . The incidence rates in Europe and Canada were very close to that in the US [23] . In the United States, mortality rates kept rising until the 1990s but headed downward in novel agents area from 2000 [45] . Compared with western countries, MM incidence rates in Asian countries were obviously lower, and the reason behind it is not clear [6] . Similar to some western countries, a stable increase in MM incidence occurred in Asia over recent decades 789 . However, considering stable incidence rates in areas with high case ascertainment in the US and Europe [1011] , factors responsible for the increase in Asia need to be investigated further.

Few population-based studies have been conducted to assess the incidence of MM in China. In Taiwan of China, from 1979 to 2003, the average age-standardized incidence per 100,000 persons was 0.75, and the age-standardized mortality took up an average of 0.59 per 100,000 persons [12] . The age-adjusted incidence increased from 0.36/100,000 in 1979–1983–1.21/100,000 in 1999–2003 [12] . In 1997–2013, the age-adjusted incidence increased further to 1.83 /100,000 [13] . But MM mortality from 1997 to 2013 was 0.44 per 100,000 individuals and decreased compared with that between 1979 and 2003 [1213] . According to the reports by Global Burden of Disease, there were about 16,500 new cases with MM diagnosed and 10,300 died in the mainland of China in 2016 [14] . The age-standardized incidence rate (ASIR) and mortality rate (ASMR) were 1.03 and 0.67 per 100,000 persons, respectively in 2016 [14] . The ASIR increased significantly from 2006 to 2016. Accordingly, the ASMR continued to increase from 2006 to 2014, but remained stable since 2014 [14] . In another study, the researchers took advantage of the national basic medical insurance database between 2012 and 2016 in China to estimate the prevalence and incidence of MM. The standardized prevalence of MM was 5.68 per 100,000 population and the standardized incidence rate was 1.15 per 100,000 population [15] . The standardized incidence was close to the above-mentioned research [14] .

However, all the above-mentioned studies in China were based on the data from central cancer registries. There was inevitably bias for results obtained with this method owing to variations with time like diagnostic criteria, available medical care and so on for all residents. Furthermore, these studies were based on retrospective registration. There is a lack of a large-scale prospective study on incidence and mortality rates of MM. The Kailuan study is a prospective, dynamic cohort study on risk factors and intervention for chronic disease in the Kailuan community. We made use of the database of the Kailuan Study (registration no. ChiCTR-TNRC11001489) to prospectively calculate the incidence and mortality rates of MM in Chinese community population. In addition, in order to understand the Kailuan cohort mortality better, both the clinical manifestation and treatment pattern were compared between the MM patients from the Kailuan cohort and patients from Beijing Chaoyang Hospital.