Epidemiology of multiple myeloma in Taiwan: increasing incidence for the past 25 years and higher prevalence of extramedullary myeloma in patients younger than 55 years.

BACKGROUND

The incidence of multiple myeloma (MM) is lower in Asia than in western countries. However, no data are available on descriptive epidemiology of MM in Chinese.

METHODS

From 1979 to 2003, 3602 MM patients were registered in the Taiwan National Cancer Registry. The annual incidence and mortality were calculated and age-standardized to the world standard population in the year 2000. Age-period-cohort effects on incidence were analyzed. The salient clinical data of 526 MM patients in a single institute were also investigated.

RESULTS

From 1979 to 2003, the average age-adjusted incidence per 100,000 population was 0.75. The incidence increased with age to a peak of 5.2 in those aged 75-79 years. In addition to age, remarkable period and birth cohort effects were found to contribute to increased incidence of MM. The age-adjusted mortality also increased, which accounted for an average of 0.59 per 100,000 deaths; however, the fatality rate was steady at 80%. Clinical and laboratory characteristics and treatment outcomes of the 526 MM patients were similar to those reported elsewhere. Remarkably, extramedullary myeloma (extra-MM) at diagnosis was more common in patients younger than 55 years of age than in others (43% vs 13%, P < .001).

CONCLUSIONS

Incidence of MM in Taiwan has dramatically increased in recent years and is associated with a birth-cohort effect. There are no apparent differences in treatment outcome between MM patients in Taiwan and in other countries. However, prevalence of extra-MM is higher in patients younger than 55 years of age.