Multinational trends in multiple myeloma.

Reported mortality rates from multiple myeloma have been increasing in all industrialized countries in the last 20 years. The rate of increase shows a strong interaction with age: it is slow in persons aged 55 to 59, and increases steadily with increasing age to reach rates of increase in excess of 4% per year in persons 85 years and older. The rate of increase is moderately consistent across sexes and countries. Multiple myeloma is one of the best ascertained cancers, which argues against better ascertainment as the sole cause of the increasing trend. Cohort plots in the United States suggest a parallel shift upward in risk between the birth cohorts of 1870 and 1910, with no evidence of differential effects in the elderly. This suggests a real increase is occurring as a result of some general environmental factors.