Could Blood Calcium Levels Warn of Ovarian Cancer?
Madison, Wisconsin - A large population-based study by the University of Wisconsin Carbone Cancer Center (UWCCC) and Wake Forest University shows that higher levels of calcium in blood could be an early warning sign of ovarian cancer.
In two long-term follow-up studies, women with higher levels of serum calcium were more than two and a half times as likely to later develop ovarian cancer.
Senior author Dr. Halcyon Skinner, assistant professor of population health sciences at the University of Wisconsin School of Medicine and Public Health and a member of the Carbone Cancer Center, says this is the first time that higher blood-calcium levels have been shown as a biomarker for the most fatal and difficult to diagnose of the gynecologic cancers.
“I don’t think there will be a single biomarker for ovarian cancer, but in women in whom ovarian cancer is suspected, it may be valuable to examine their calcium levels in addition to other markers,” says Skinner. He cautions that confirmatory studies are needed due to the relatively low number of ovarian cancer cases in the two cohorts.
Skinner and colleagues used data from the third National Health and Nutrition Survey (NHANES III), which showed 11 deaths from ovarian cancer over more than 95,000 person-years of follow-up. They found that the risk of ovarian cancer was 144 percent higher for each 0.1 millimole per liter increase in ionized calcium.
The association held true when they looked at a second large study, the NHANES Epidemiological Follow-Up Study (NHEFS). In that study, eight women developed ovarian cancer over 31,089 person-years of follow-up. Like the women in the first study, those who developed ovarian cancer had higher calcium levels in their blood years before the cancer was diagnosed.
In the second study, researchers estimated ionized calcium levels based on total calcium levels. (Total calcium is a less expensive and simpler test, and because ionized calcium makes up 45 percent of the total calcium level, that level can be estimated without testing for it directly.)
The scientists adjusted the results for such confounding factors as the use of birth control pills and childbearing.
First author, Dr. Gary G. Schwartz, of the departments of cancer biology, urology, and epidemiology and prevention at the Wake Forest School of Medicine says the relationship between ovarian cancer and blood calcium may be related to secretion of a factor like parathyroid hormone-related protein (PTHrP) by undetected ovarian cancers, which acts to raise calcium levels in serum.
The research was supported by the UW School of Medicine and Public Health. The study was published online in the journal of Gynecologic Oncology.
Date Published: 01/22/2013