Study suggests a link between sickle cell disease and blood cancer risk
Available data is very limited, thwarting the ability to reach a better conclusion
People with sickle cell disease (SCD) may have a higher risk of developing blood cancer, but a lower risk of certain types of solid tumor malignancies, such as breast and prostate cancer, a systematic review study suggests.
The study, “Risk of cancer in patients with thalassemia and sickle cell disease: a systematic review,” was published in the Annals of Medicine.
A genetic disorder, SCD features the production of an abnormal form of hemoglobin, the protein red blood cells use to carry oxygen throughout the body. This abnormal hemoglobin tends to form clumps inside red blood cells, deforming them and making them prone to premature destruction, and to getting stuck inside blood vessels, restricting or blocking blood flow.
Some studies suggest people with SCD may be at higher risk of developing certain types of cancer, especially blood cancer. “Yet the full extent of this risk remains inadequately characterized,” wrote researchers in Italy, who systematically reviewed the literature to better understand SCD’s association with cancer. They also examined the link between cancer and thalassemia, another genetic disorder that affects hemoglobin. The review covered data from five studies — two in SCD, two in thalassemia, and one that covered both.
Limitations, inconsistencies impede firm conclusions
Many studies had significant limitations, such as not fully accounting for how other factors like infections or treatment patterns might affect cancer risk. There was also a lot of variability across the studies in the types of populations used as references for estimating cancer rates.
“The [variability] of the research, characterized by substantial differences in study design, population characteristics, interventions, and outcomes, was a significant limitation, preventing direct comparisons and robust meta-analysis,” wrote the researchers, who noted the studies were mainly from Europe and the U.S., where SCD is relatively rare. There were no studies from Africa, the Middle East, or South Asia where it’s more common. “The exclusion of these populations is significant since the genetic and environmental factors influencing the incidence and management of these conditions are highly variable across different settings. Including data from high-prevalence areas is crucial for developing a more comprehensive understanding of disease patterns and informing culturally appropriate healthcare interventions.”
The results also weren’t consistent from study to study. For example, a study of Black SCD patients in England indicated the risk of cancer was more than twice as high in people with SCD relative to the general population, but an analysis from California suggested cancer incidence was generally about 20% lower in SCD. Conflicting results were also seen for thalassemia.
The available data did consistently indicate that people with SCD were more likely to develop blood cancer such as leukemia and lymphoma, but people with SCD may be less likely to develop certain solid cancers, particularly of the breast and prostate. Only one study looked at rates of cancer-related mortality in SCD, finding they were comparable to the general population.
Despite the notion that SCD may affect cancer risk being generally supported, particularly with blood cancer, drawing firm conclusions without more data is difficult because of the limitations. The researchers called for further studies to explore the relationship between SCD and cancer, and for registries to collect more information.
“Studies should document cancer incidence by exposure, using transparent reporting methods and ideally population-based data. Collaboration with specialized centers and registries can enhance data quality, while ensuring robust statistical power requires sufficient sample sizes. This approach would improve the reliability and generalizability of findings, providing a clearer understanding of cancer risks in thalassemia and SCD populations,” they wrote.
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