For some common cancers, including cancers of the breast, large bowel, bladder, and uterus, low socioeconomic status (SES) has been linked to higher risk and poorer outcome. The relationship between SES and blood cancers such as myeloma in developed countries remains relatively unexplored, however.

Physicians at the Karolinska University Hospital at Solna and the Karolinska Institute in Stockholm recently showed a positive correlation between high (SES), survival rate for multiple myeloma, and acute myeloid leukemia (AML) among patients listed in the Swedish Cancer Register. The register contains a comprehensive and highly accurate record of cancer diagnoses in Sweden for the past 30 years.

A 31 percent lower risk of death was found for higher white-collar workers diagnosed from 2000 to 2005, compared to blue-collar workers. Patients diagnosed between 1973 and 2000 showed a similar, but weaker, relationship.

For myeloma and AML, higher mortality was found for self-employed individuals, farmers, blue-collar workers, and retired individuals compared to higher white-collar workers.

Interestingly, the 31 percent difference in the risk of death from 2000 to 2005 coincides with the introduction of the newer, more powerful drugs on the market for blood cancers.

The authors of the study researched a few possible causes for the discrepancy between socioeconomic groups, and found that distance to the medical facilities may be the main impacting factor.

Presumably, a greater percentage of higher SES individuals live in urban areas in close proximity to the better medical facilities. For those who live in the countryside, longer travel times may deter an ailing individual from seeking proper treatment.

Studies have shown that people of low SES may present with more advanced disease. Research on multiple myeloma patients, however, has produced conflicting evidence both for and against the theory that up to a 6-month delay in medical treatment can adversely affect survival.

Another possibility is that the health care provider's attitude toward managing the disease may differ for patients with higher and lower SES. Some speculation exists as to whether health care providers may follow through with a more extensive medical work-up for patients in lower socioeconomic groups. However, no published data exist, particularly with respect to AML and myeloma patients.

The database used for this study inherently eliminates other patient-related factors such as access to healthcare and the discrepancies of nonnative status.

Sweden's well-established public health system is available to any resident, regardless of financial standing. Furthermore, Sweden has a largely homogenous white population, eliminating racial discrepancies. The inclusion of immigrants insignificantly affected the results.

To produce these findings for their study, the authors analyzed data on patients diagnosed with multiple myeloma and AML from 1973 to 2005. Because SES was not directly available, type of occupation was used as a proxy for SES. In addition, a spouse's occupation was substituted where none was listed. Approximately two-thirds of individuals were either lower white-collar worker or blue-collar. Higher white-collar workers, self-employed individuals, farmers, retired, and unknown categories comprised less than 10 percent each.

Irrespective of the underlying reasons, this study produces a highly relevant finding that higher SES means a better chance of survival for blood cancer patients and that this relationship has increased since the advent of more powerful treatments.

For more information, please see the full article in the Journal of Clinical Oncology ^[1].