THURSDAY, Dec. 3, 2020 — Major birth defects are associated with an increased, lifelong risk of cancer, researchers say.
It has been known that people with major birth defects have a greater risk of developing cancer as children and teens, but it wasn’t clear whether the risk extends into adulthood.
To find out, Norwegian researchers compared more than 62,000 people in Scandinavia, aged 46 and younger, who had been diagnosed with cancer with a “control group” of more than 724,000 with no cancer diagnosis.
The analysis revealed that 3.5% of those in the cancer group had a major birth defect, compared with 2.2% of those in the control group. Overall, cancer risk was 1.74 times higher for people who had major birth defects than for those without.
The cancer risk was greatest in children up to age 14 (2.52 times higher) then declined with age. But it was still 1.22 times higher in adults aged 20 and older with major birth defects.
A higher cancer risk throughout adulthood was particularly evident in people with congenital heart defects, defects of the genital organs or nervous system, skeletal dysplasia (affecting bones and joints) and chromosomal abnormalities (too few or too many chromosomes or missing, extra or irregular portion of chromosomal DNA).
The type of birth defect had a significant impact on the risk and type of cancer. For example, cancer risk was highest (5.5 times higher) in people with chromosomal abnormalities such as Down syndrome, the findings showed.
Leukemia was the most common type of cancer in people with birth defects caused by chromosomal abnormalities, according to the report published online Dec. 2 in the BMJ.
Structural birth defects — such as those affecting the eyes, nervous system and urinary organs — were associated with later cancer in the same location, the researchers said in a journal news release.
The study suggests that birth defects and some types of cancer may share a common genetic or environmental cause, or a combination of the two.
“Our study showed that birth defects are associated with risk of cancer in adulthood as well as in adolescence and childhood, a finding of clinical importance for health care workers responsible for follow-up of individuals with birth defects,” the authors wrote.
Dagrun Daltveit, a senior engineer in the department of global public health and primary care at the University of Bergen, led the study.
“The most important implication of our results is to provide further rationale for additional studies on the molecular mechanisms involved in the developmental disruptions underlying both birth defects and cancer,” the study authors concluded.
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