People with a birth defect also have an increased risk of cancer as an adult compared to the general population. However, the absolute probability is small in most cases. This is evident from Scandinavian register research about which Dagrun Daltveit et al. Write in The BMJ.
It has been known for some time that children with congenital anomalies have an increased risk of malignancy. Daltveit and others used registers from Denmark, Finland, Norway and Sweden to check whether this was still the case later in life. They found nearly 63 thousand people under the age of 46 with a cancer diagnosis, and they matched it (on the basis of year and country of birth) with 724 thousand people without this diagnosis.
Mostly in children up to 14 years old
Of the people who had ever had cancer, 3.5 percent had a major birth defect, compared to 2.2 percent of the control group. The risk of cancer in people with a birth defect was most increased in children up to 14 years of age, but also increased even more in adults (> 19) (odds ratio 1.22).
Especially people with congenital heart defects, disorders of the genitalia or nervous system, skeletal dysplasia or chromosomal abnormalities also had an increased risk of malignancy later in life.
The type of congenital condition largely determines which tumor is more likely. Leukemia is most common with chromosomal abnormalities, with abnormalities of, for example, eye, nervous system or urinary tract malignancies of those parts of the body. Incidentally, some cancers involved very small numbers that Daltveit et al. Used, so that the calculated odds ratios are not reliable.
Absolute probability remains low
It is important to note that the absolute chance of a tumor remains low. The authors themselves state that the cumulative risk of malignancy in 0-44 year olds is about 3 percent. An increase of 20 percent would amount to an absolute risk increase of 0.6 percent. Commentators Logan Spector and Lazaros Kochilas consider the low incidence of cancer in adults under 50 to be an important argument against screening.
It is not yet sufficiently clear how the relationship between cancer and birth defects works. In addition to genetic factors, environmental conditions (exposure to sunlight) or iatrogenic elements (certain medications) can also play a role. Spector and Kochilas therefore argue for further unraveling the way in which the increased risk of cancer arises, in order to be able to take preventive measures for this.