Researchers recently reported updated survival rates for multiple myeloma patients in the United States. The results show that survival has improved steadily – and markedly – from 1998 to 2009.
The average newly diagnosed myeloma patient 15 years ago, for example, was about one-third as likely as someone without myeloma to live another five years.
By the end of the 2000s, in contrast, that same myeloma patient would be 45 percent as likely as someone without myeloma to live another five years.
Ten-year myeloma survival rates also increased markedly. However, the average newly diagnosed myeloma patient in the late 2000s was still only 25 percent as likely to live an additional ten years as a member of the general population.
Although the new study traces overall trends in survival, its focus is on trends in survival by ethnicity and age.
The study authors report that Non-Hispanic whites experienced the greatest improvements in survival in the period covered by their study, followed by African-Americans and Hispanics. The survival of Asian and Pacific Islanders also improved, but not as much as in the other ethnic groups.
The findings indicate that myeloma patients belonging to ethnic minorities have not benefited as much from new myeloma treatments as non-Hispanic whites. The researchers argue that unequal access to new treatment options, due to lower socioeconomic status and poor or no health insurance, may explain the disparity in survival improvements.
The researchers also document in their study how myeloma survival has increased across all age groups during the past 15 years. This improvement, however, was substantially greater for patients diagnosed before the age of 70, compared to those diagnosed at older ages.
Indeed, although the investigators do not emphasize the point, their findings drive home the fact that new myeloma treatments introduced during the past 15 years have primarily benefited younger myeloma patients. Improvements in the survival of older myeloma patients have been much more limited, and the survival of older myeloma patients remains significantly lower than that of younger patients.
The researchers recognize that their analysis did not account for several important factors, such as chromosomal abnormalities, stage of myeloma, prior lines of chemotherapy, and insurance coverage.
Further research is therefore needed, they write, to fully assess the impact of ethnicity and age on myeloma survival.
While multiple myeloma remains a largely incurable disease, studies have shown that survival for myeloma patients has improved substantially over the last few decades. Improvements in survival occurred in the 1990s due to the wider use of stem cell transplantation, and continued in the 2000s with the introduction of novel anti-myeloma agents such as thalidomide (Thalomid), Velcade (bortezomib), Revlimid (lenalidomide).
However, according to the authors of the current study, it is not clear whether survival has increased equally across all ethnic and age groups.
Results from a previous study showed little difference in myeloma survival rates between Asians, African-Americans, and non-Hispanic whites. However, the study was based on data from patients diagnosed prior to 2003, meaning it could not address potential differences in the impact of novel agents on survival across ethnic groups.
The researchers therefore sought to assess changes in the survival of multiple myeloma patients – overall, and by ethnicity and age – in the first decade of the 21st century.
An international group of researchers analyzed the records of 26,391 U.S. multiple myeloma patients using the National Cancer Institute’s Surveillance, Epidemiology, and End Results (SEER) database, which was started in 1973 and is now a key source of U.S. cancer statistics.
The SEER database houses information about a large sample of U.S. cancer patients, including data about each patient’s type of cancer, general demographic characteristics (age, gender, and race), type of initial treatment, and survival.
The investigators included in their analysis patients with symptomatic (active) myeloma who were at least 15 years of age and who were diagnosed between 1993 and 2009. The median age of the patients included in the analysis was 67 years.
The study authors separated the patients into four groups based on their ethnicity: Asian and Pacific Islander, African-American, Hispanic, and non-Hispanic white.
In addition, the patients were separated into three age groups: 15 to 49 years old, 50 to 69 years old, and over 70 years old.
The investigators calculated myeloma survival rates for the following three time periods: 1998 to 2001, 2002 to 2005, and 2006 to 2009.
The survival rates calculated by the authors are what are known as relative survival rates. These are different than the survival rates typically seen in myeloma research articles, which are technically absolute survival rates.
It is common in myeloma research studies to find statements such as “The five-year survival rate was 60 percent.” This (absolute) survival rate means that, five years after their myeloma diagnosis, 60 percent of the patients in the study were still alive.
The 60 percent absolute survival rate, however, does not put the survival experienced by the myeloma patients into perspective. More specifically, it does not say how many more myeloma patients died over the course of the five years compared to how many people in the general population – of the same age, gender, and ethnicity – would have died during the same period.
Relative survival rates, on the other hand, provide such perspective. They take into account that people without myeloma also die.
In particular, the relative survival rate is calculated by dividing the absolute survival rate for a group of cancer patients by the absolute survival rate for a similar group of people from the general population.
As an example, take the (fictitious) study mentioned above with the 60 percent absolute five-year survival rate. Assume that a large group of people similar in age, gender, and race to those in the study – but from the general population – would have experienced an 80 percent absolute survival rate over the same five-year period.
In that case, the relative survival rate of the myeloma patients in the study would be 75 percent (60/80=0.75, or 75 percent).
Absolute and relative survival rates will be very similar for younger myeloma patients, because younger people from the general population do not die that often. Relative survival rates for older myeloma patients, on the other hand, will be higher than their corresponding absolute survival rates.
The researchers found that the five-year relative survival rate for all myeloma patients increased from 35 percent during the 1998-2001 time period, to 40 percent during 2002-2005, and to 45 percent during 2006-2009 (see graph on the right).
The investigators observed a similar trend for the ten-year relative survival rate. It increased from 16 percent during the 1998-2001 time period, to 20 percent during 2002-2005, and to 25 percent during 2006-2009.
However, the investigators noted differences in the survival rate changes experienced over time by different ethnic groups.
Non-Hispanic white myeloma patients had the highest change in five-year survival rate from 1998 to 2009 (9 percent), followed by African-American patients (8 percent), Hispanic patients (7 percent), and Asian and Pacific Islander patients (6 percent).
In the latest time period, and after adjustment for age distribution differences across ethnic groups, the five-year relative survival rates were 45 percent for non-Hispanic whites, 42 percent for African-Americans, 40 percent for Hispanics, and 43 percent for Asian and Pacific Islanders.
The most recent ten-year relative survival rates were 25 percent for non-Hispanic whites, 22 percent for African-Americans, 22 percent for Hispanics, and 28 percent for Asian and Pacific Islanders.
According to the researchers, there is currently no evidence that novel agents are less effective in minority patients. They therefore speculate that lack of access to these treatments – and, more broadly, to state-of-the-art medical care – may have contributed to the lower increases in survival among minority myeloma patients.
The investigators also found that younger patients had higher survival rates and greater improvements in survival rates over the past 15 years, compared to older patients (see graph to the right).
Specifically, patients who were diagnosed between 15 years and 49 years of age had the highest five-year relative survival rate in the most recent time period (66 percent), followed by those who were diagnosed between 50 years and 69 years of age (52 percent), and those who were diagnosed when they were at least 70 years of age (31 percent).
The increases over time in the five-year relative survival rates were similar among patients younger than 50 years of age and patients between 50 years and 69 years of age (13 percent for both). However, the increase was much smaller for patients 70 years of age and older (5 percent).
The ten-year relative survival rates in the most recent period were 47 percent for the youngest age group, 30 percent for the middle age group, and 13 percent for the oldest age group (see graph to the right).
The researchers once again observed improvements over time when looking at trends in the ten-year survival rates, although improvements were heavily concentrated among younger myeloma patients. The ten-year survival rate increased 13 percent for patients younger than 50 years of age, 12 percent for patients between 50 years and 69 years, and just 3 percent for patients 70 years and older.
For more information, please see the study in the journal Leukemia and Lymphoma (abstract).