Multiple myeloma rates have stayed steady among all age ranges over the past 50 years, according to a study published in Mayo Clinic Proceedings this month. The research, which tracked multiple myeloma diagnoses among all the residents of Sweden’s third-largest city, Malmo, between 1950 and 2005, contradicts the results of several previously-published studies that found that multiple myeloma rates increased in the 1960s and 1970s.

“The message of the paper is that age-adjusted [risk of developing] myeloma has been stable over 56 years.” wrote Dr. Ingemar Turesson, the study’s lead scientist, in an e-mail to The Myeloma Beacon. “My belief is that earlier reports on increasing (age-adjusted) [risk] of myeloma is explained by better access to health care in older individuals, better awareness of the diagnosis, etc.” His study and a similar one conducted in Olmsted County, Minnesota, support his ideas, he added.

Increasing multiple myeloma rates over time may suggest that environmental factors contribute to the development of multiple myeloma. The longer people are exposed to these factors, the more likely they are to get sick.

However, this new study joins a few others in finding stable multiple myeloma rates, which do not support the idea that environmental factors play a role in the diagnosis of multiple myeloma.

The study also provides evidence against some cancer centers’ anecdotal reports that they have seen increased numbers of younger myeloma patients. These reports are “mentioned and discussed in various contexts, such as scientific meetings, but not really published as far as I know,” wrote Dr. Turesson.

“I found no increase of [risk] in any age group,” he noted. But he also stated that there were so few Malmo residents under 50 years old who had multiple myeloma that his study cannot definitively say if there have been any changes in myeloma rates among them.

To calculate multiple myeloma rates, researchers often rely on data from central cancer registries. The Swedish researchers pointed out that information from central cancer registries may be biased due to progressive diagnostic tools, variations in data reporting, and differences in health care access.

To overcome these potential biases, the Swedish researchers suggested collecting data in a defined population with unrestricted access to health care and reviewing individual patient records to ensure the consistent use of diagnostic tools.

For their study, which they described as the “the longest and largest” on rates of multiple myeloma in a defined population, the scientists searched hospital records, the Swedish Cancer Registry and autopsy registries in the city of Malmo, Sweden, to identify all the city’s residents who had been diagnosed with multiple myeloma between 1950 and 2005.

They examined each multiple myeloma patient’s medical records to determine the patient’s sex, age, and how his myeloma diagnosis was made. They used city census data to calculate multiple myeloma rates for different age ranges.

Overall, they analyzed the medical records of 773 Malmo residents with multiple myeloma, out of Malmo’s total population, which was 190,000 in 1950 and increased to 270,000 by 2005.

The researchers found that the rate of multiple myeloma diagnoses—the number of people diagnosed with multiple myeloma per 100,000 people—has stayed the same since 1950.

They also found that the median age at diagnosis increased from 70 to 74 years and that the share of people with multiple myeloma over 80 years also went up from 16 percent to 31 percent during the 50-year observation period.

These results point to the need for less intense therapies, the Malmo University Hospital researchers concluded in their paper. Older people with multiple myeloma often cannot tolerate intense myeloma treatments such as stem cell transplants.

The steady myeloma rates in their study suggest that major environmental changes in recent years do not seem to affect multiple myeloma, the researchers concluded. That conclusion is indirect, Dr. Turesson added in his e-mail, since his team’s research was not designed to specifically look for environmental factors’ effects on myeloma rates.

The researchers pointed out that their study had some limitations. They could not completely rule out that improvements in diagnosis since 1950 may have affected their results. Secondly, they did not have data available about moves into and out of Malmo during the research period. They added that their results may only apply to white populations and may not be applicable to other ethnicities or countries.

For more information, please see the study in the journal Mayo Clinic Proceedings ^[1] (abstract).