For much of the past century in Norway, both the average weight of pregnant women and the proportion of their newborn boys who later developed testicular cancer rose steadily. Researchers pouring over health statistics have discovered that there were temporary reversals of both trends during World War II, a hint that the two phenomena may be connected. Now, a link has been proposed.
The new link fits with evidence that males who were exposed to excess estrogen hormones at an early stage of fetal development may face an elevated risk of developing testicular cancer. Heavier women tend to have higher blood concentrations of biologically active estrogen than lighter women do.
In their study, Tom Grotmol of the Cancer Registry of Norway and his colleagues examined 3,000 Oslo birth records from 1931 to 1955 and compared them with data indicating the number of Norwegian men born during each of those years who later developed testicular cancer.
The yearly incidence of testicular cancer reflected an upward trend, from 9.4 cases per 100,000 men for those born between 1931 and 1935 to 13.9 cases for men born from 1951 to 1955, the researchers say. However, the malignancy’s incidence dipped to 8.7 cases during the war years 1941 to 1945. That was also the only period in the study that showed a decline in average maternal weight, the investigators report in the Aug. 20 International Journal of Cancer.
During World War II, consumption of foods such as milk and meat were restricted in Norway, leading to lower average weights in the population.