Risk of individual malignant neoplasms in patients with sickle cell disease: English national record linkage study

Objective: Case reports suggest that there may be an increased risk of some cancers associated with sickle cell disease. However, population-based studies are scarce and there is no comprehensive enumeration of the risks across the whole range of site-specific cancers. Our aim was to provide this. Design: We used an English national dataset of linked statistical records of hospital admissions and deaths from 1999 to 2011 to undertake a retrospective cohort study. Setting: England. Participants: Records of all hospital admissions in England with SCD or with conditions included in the control cohort. Main outcome measures: Rate ratios were calculated comparing rates of cancer in a sickle cell disease cohort and a control cohort, confining the analyses to people whose ethnicity was recorded as Black. Results: Comparing the sickle cell disease cohort with the cohort without sickle cell disease, the rate ratio for all cancers combined was 2.1 (95% confidence interval 1.7-2.5). There were significantly high rate ratios for haematological malignancies, including Hodgkin's lymphoma (rate ratio 3.7, 1.5-8.4), non-Hodgkin's lymphoma (2.6, 1.3-4.8), multiple myeloma (5.5, 2.8-10.1), lymphoid leukaemia (3.3, 1.3-8.0) and myeloid leukaemia (10.0, 4.6-21.5). Four solid tumours showed elevated rate ratios: colon cancer (2.8, 1.2-5.5), non-melanoma skin cancer (4.4, 1.3-12.2), kidney cancer (5.4, 2.3-11.5) and thyroid cancer (5.1, 1.3-15.4). Conclusions: The risk of some malignancies may be raised in patients with sickle cell disease. However, this study was based on administrative data without the scope to validate these against patients' full clinical records. Our findings need confirmation or refutation. If confirmed, work to elucidate, at the genetic and molecular level, why people with sickle cell disease have elevated risks of individual cancers might make contributions to the fundamental understanding of carcinogenesis.