Cancer antigen 125 (CA125) can predict ovarian cancer in general practice, and elevated CA125 can also indicate an increased risk for non-ovarian cancer, delegates to last week’s  2019 National Cancer Research Institute Cancer Conference in Glasgow, Scotland, were informed in two study presentations.

Garth Funston, Ph.D., from the University of Cambridge in the United Kingdom, and colleagues calculated the predictive value of CA125 for ovarian cancer in U.K. general practice. The researchers found that 0.9 percent of the 50,780 women with possible symptoms who underwent CA125 testing were diagnosed with ovarian cancer.

CA125 had a threshold positive predictive value (PPV) of 15.2 and 3.4 percent in women ≥50 years and <50 years, respectively, with a cut-off of ≥35 U/mL. CA125 levels of 41 U/mL and 76 U/mL equated to an ovarian cancer point PPV of 3 percent in women ≥50 and <50 years, respectively.

In a second study, Funston and colleagues examined the incidence of non-ovarian cancers among women with elevated CA125 in general practice. The researchers found that 3.7 percent of the 31,086 women ≥50 years and 0.8 percent of the 19,694 women aged <50 years who underwent CA125 testing were diagnosed with non-ovarian cancer.

Overall, 17.3 and 2.8 percent of women aged ≥50 years with a raised CA125 and with normal CA125, respectively, were diagnosed with non-ovarian cancer.

Among women aged <50 years, the corresponding proportions were 2.7 and 0.7 percent. Cancers in which CA125 was elevated were mainly from sites in the chest, abdomen, and pelvis.

“Women with symptoms who are aged 50 years or more and have abnormally high CA125 levels frequently have other types of cancer,” Funston said in a statement.

“It is really important that general practitioners are aware of this to ensure these cancers are not missed.”