No Overall Increased Risk of Cancer in Children Born After Assisted Conception in UK
In a study reported in The New England Journal of Medicine, Carrie L. Williams, MB, BCh, of University College London, and colleagues analyzed risk for cancers among UK children born after assisted conception. They found no increased risk of cancer overall or for individual cancer types except hepatoblastoma and rhabdomyosarcoma, and the absolute risk for these cancers was small.
Study Details
In the study, data on all children born in the United Kingdom between 1992 and 2008 after assisted conception without donor involvement were linked with data from the United Kingdom National Registry of Childhood Tumours to identify children in whom cancer developed before 15 years of age. Cohort cancer rates were compared with population-based rates in the UK during the same period with stratification for factors including sex, age at diagnosis, birth weight, singleton vs multiple birth, parity, parental age, type of assisted conception, and cause of parental infertility.
No Overall Increased Risk of Cancer
In total, 106,013 children born after assisted conception were identified (representing 700,705 person-years of observation). The average duration of follow-up was 6.6 years. A total of 108 cancers were identified, which was not significantly different from the expected total of 109.7 in the general population (standardized incidence ratio [SIR] = 0.98, P = .87).
Compared with expected rates in the general population, assisted conception was not associated with significantly different risk of leukemia (34 observed cases vs 37.5 expected cases, SIR 0.91), central nervous system tumors (22 vs 25.6 cases, SIR = 0.85), neuroblastoma (9 vs 10.2 cases, SIR = 0.88), retinoblastoma (< 5 cases vs censored, SIR = 0.59), renal tumors (8 vs 8.5, SIR = 0.94), or germ cell tumors (< 5 cases vs censored, SIR = 0.56).
Increased Risk of Hepatoblastoma and Rhabdomyosarcoma
Assisted conception was associated with an increased risk of hepatic tumors (6 vs 1.8 cases, SIR = 3.27, P < .05), with all observed tumors being hepatoblastomas (SIR = 3.64, P = .02). The absolute excess risk of hepatoblastoma was 6.21 cases per 1 million person-years. The increase in risk was associated with low birth weight (SIR = 10.29, P = .002, for birth weight < 2,500 g; SIR = 56.96, P = .01, for birth weight < 1,000 g).
Assisted conception was also associated with increased risk of bone tumors and extraosseous sarcomas (20 vs 8.6 cases, SIR = 2.34, P < .01). This excess risk was mostly accounted for by increased risk for rhabdomyosarcoma (10 vs 3.8 cases, SIR = 2.62, P = .02), representing an absolute excess risk of 8.82 cases per 1 million person-years. Risk of rhabdomyosarcoma did not differ significantly by age at diagnosis, birth weight, or gestational age, but increased risk was observed among multiple births (SIR = 3.66, P < .05). The authors noted that this latter finding was surprising, since rhabdomyosarcoma is not known to be associated with low birth weight.
Among other types of bone tumors and extraosseous sarcomas, assisted conception was associated with nonsignificantly increased risk of osteosarcoma (SIR = 2.95), Ewing’s sarcoma (SIR = 2.47), and other sarcomas (SIR = 1.42).
The investigators concluded, “There was no increase in the overall risk of cancer among British children born after assisted conception during the 17-year study period. Increased risks of hepatoblastoma and rhabdomyosarcoma were detected, but the absolute risks were small.”
The study was supported by Cancer Research UK, the National Institute for Health Research, Children with Cancer UK, the National Cancer Intelligence Network, the Scottish government, and the Department of Health for England and Wales.
Alastair G. Sutcliffe, MD, PhD, of University College London, is corresponding author for this study. Dr. Williams and Kathryn J. Bunch, MA, of University of Oxford, contributed equally to the described work.
The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.
