According to the study, women who had suffered from preeclampsia appeared to have about a 30 percent increased risk of cancer in general, compared with women who had not developed the condition during pregnancy.When Rivka A. gave birth to her son in a Jerusalem hospital in 1972, she had been suffering from preeclampsia.
A common complication of pregnancy, preeclampsia is a condition that is marked by high blood pressure after the sixth month. Rivka also suffered from other common symptoms like protein in the urine and swollen ankles from fluid buildup. Preeclampsia can cause a list of problems, even death, for both the mother and the fetus.
Rivka recovered from the ailment and went on to enjoy good health for many years before developing breast cancer in 1992. It did not appear initially that there existed a connection between these two different health problems. But thanks to a far-reaching Israeli project which tracked thousands of women like Rivka, that connection has been made, with implications for all women who suffer from preeclampsia.
According to the Israel study, women with a history of preeclampsia may have a higher risk of developing cancer, especially cancers of the stomach, breast, ovary, lung and larynx. The findings which appeared in the British Medical Journal, while preliminary, suggest there might be some common environmental or genetic factor under girding both preeclampsia and cancer.
Previous studies have shown either no association between preeclampsia and cancer, according to the chief researcher Dr. Ora Paltiel of the Hebrew University-Hadassah Braun School of Public Health and Community Medicine.
“With these new findings, we have to speculate that it’s either something specific to the population, or maybe to do with diet, or genetic factors common to both preeclampsia and cancer which are specific to the population,” she told ISRAEL21c.
Preeclampsia occurs in close to ten percent of pregnancies, and most often in the first pregnancy. It can be mild or severe, in which case it can lead to eclampsia, in which seizures or coma can kill the mother and the fetus. Women who are overweight or suffer from hypertension before they become pregnant are at a higher risk for pre-eclampsia.
Paltiel’s team – which included staffers at the Israel Cancer Registry, Yeshiva University’s Einstein College of Medicine, and Columbia University – compared the subsequent incidence of cancer among 37,033 women who had delivered babies in three large hospitals in Jerusalem between 1964 and 1976. Ninety-nine percent of the women were Jewish. Cancer eventually developed in 91 women who had pre-eclampsia and 2,204 who did not.
Women who had suffered from preeclampsia appeared to have about a 30 percent increased risk of cancer in general, compared with women who had not developed the condition during pregnancy. The risk of breast cancer was almost 40 percent higher.
However, Paltiel cautioned that women should not panic over the findings. “I would stress that although the findings are statistically significant, the size of the risk is small and women should not be alarmed by the findings,” she said.
The database was a researcher’s dream come true – The Jerusalem Perinatal Study compiled information almost 40,000 Israeli women who gave birth to over 90,000 babies in Jerusalem hospitals between 1964 and 1976.
During 1998-2002, the project traced 98% of the offspring (median age 30) and 94% of their mothers and linked them to Israel’s Population Registry and its Cancer Registry. The median follow-up time for checking the women was 29 years.
“The special thing about this study is the uniqueness of the cohort. People had the foresight in the 1960s and 70s to systematically survey every woman who gave birth.
It’s not a haphazard selection process but population based and systematical,” explained Paltiel. “It provides the most valid data base for proving research on future outcome. This unbiased sample includes everyone, it’s an ethnic mix.”
The ethnic distribution is unique, Paltiel explained. “We have women from Ashkenazi, Sephardic background, Arab women, even the Sephardic women are varied – many are Kurdish as many of the Jews living in Jerusalem in the ’60s came from Kurdistan.”
The question of why there might be a relationship between preeclampsia and cancer remains unanswered, said Paltiel. “We studied an epidemiological association and can only speculate about the mechanism behind our findings. We might theorize that factors related to cancer may be operating in preeclampsia and vice versa. These might include diet (such as folate deficiency), angiogenesis (new blood formation) and thrombosis (blood clotting).
“Some genes may be common to both cancer and preeclampsia development. There is also the possibility that some of our findings are due to chance, given the small number of cases at some sites,” Paltiel added.
The findings will need to be confirmed in other studies and in other populations, Paltiel said. “Scientists should be challenged to confirm the findings and try to determine the mechanisms.”
Paltiel’s team plans to probe the latter issue. “We’re starting to explore the mechanism to find a common genetic and environmental connection for preeclampsia and cancer. We’re also investivating the blood clotting system,” she said.