23-year Study of Cancer Incidence Among SCD Patients is a Mixed Bag

Researchers have found that patients with sickle cell disease (SCD) have increased risk of developing leukemia, but lower risk for breast cancer or male genital cancers.

These findings resulted from a population-based study titled “Increased risk of leukemia among sickle cell disease patients in California” that was published in the journal Blood.

In the past 50 years, advances in science and medicine have improved the overall care and treatment provided to patients with SCD. This represents an important milestone for this population and has had a great impact on patients’ life expectancy. However, this progress means these patients have to face other health-related issues and complications, such as incidence of age-related diseases.

Incidence of cancer has become a matter of concern among SCD patients. Some studies have found an association between SCD and cancer development. However, it is not fully clear if this population has higher risk of developing cancer compared to the general population, or which cancers they are more prone to develop.

To shed light on this matter a team of researchers at the University of California conducted a population-based analysis to assess cancer incidence among patients with SCD.

“To our knowledge, this is one of the first studies to determine cancer incidence among SCD patients compared to a general population,” the researchers wrote.

Based on clinical information collected from the California Patient Discharge Data and the Emergency Department Utilization databases, the team analyzed data from a total of 6,423 individuals who were identified as SCD patients between 1991 and 2014.

They next crossed the patient’s clinical information with data from the California Cancer Registry. This analysis strategy revealed a total of 115 cases of patients with SCD who were diagnosed with first primary cancers during the study time period of 23 years.

SCD patients were found to have 72 percent higher risk of blood cancers and 38 percent lower risk of solid tumor, when compared to the general population. In addition, the researchers also found that SCD patients had a lower incidence of breast cancer and male genital cancers.

This population had a two-fold increased risk for leukemia, in particular acute myeloid leukemia and chronic lymphocytic leukemia. Female SCD patients and those 15 to 39 years old, as well as patients with severe SCD were found to be risk groups for leukemia, as they had three times and four times increased risk for this type of cancer, respectively.

The high cellular turnover, in particular in the bone medulla, and chronic inflammation that SCD patients present, may contribute to the development of blood cancers, researchers explained in their report.

Approved by the FDA as treatment for SCD since 1998, hydroxyurea also has been perceived as a contributor for cancer development. However, the team did not find any increase in cancer frequency in the SCD population, suggesting no association between hydroxyurea use and cancer incidence. “Future studies with hydroxyurea data will need to confirm these findings,” the researchers added.

“Despite the lower incidence of solid tumors, recommendations for routine screening for the common cancers, such as breast and colon, should continue to be followed for this population,” the researchers wrote. “However, healthcare providers should be aware of the possibility of an increased risk of leukemia among SCD patients.”

Additional studies conducted in larger groups of patients are warranted to further confirm these findings because improved knowledge about cancer risk factors and impact on survival in the SCD population are still necessary.