A new study investigating a simple screening method for ovarian cancer may help physicians catch and treat the deadly disease earlier. The researchers’ encouraging results, if confirmed by an upcoming larger study, may ultimately lead to regular screening for women at average risk of ovarian cancer and could significantly impact survival rates.
Researchers in the study, which was published this week in the journal Cancer, used a simple blood test to track the levels of a protein called CA-125 over time in more than 4,000 women. The study’s subjects were between the ages of 50-74 and had no strong family history of breast or ovarian cancer. Based on their initial CA-125 numbers, women were classified as low, intermediate or high risk. Low-risk women were rescreened after one year, and intermediate risk women were screened again after three months. High-risk women were referred to undergo a transvaginal ultrasound and consult with a specialist to check the ovaries for signs of disease.
Of the women in the study, 10 underwent surgery due to concern for cancer. Four women who were initially classified as low risk were ultimately diagnosed and treated for invasive ovarian cancer after their CA-125 levels rose significantly during the course of the study. Encouragingly, though these four women had the most aggressive form of the disease, their cancers were all caught at early stages, when the disease is still highly treatable. Of the six other women who had surgery, two had borderline disease, one had endometrial cancer and three had benign tumors. Currently, all of these women are still alive and disease-free following treatment.
Ovarian cancer has historically been difficult to diagnose and treat, largely because it is often asymptomatic until it has spread. According to one of the study’s authors, over 70% of women with ovarian cancer are diagnosed when the disease is already late-stage, which may explain why ovarian cancer causes more deaths than any other gynecologic cancer. Late-stage ovarian cancer has survival rates under 30%, while survival for early-stage cancer is between 75-90%. If caught early enough, ovarian cancer is often curable, but there is currently no standardized screening method for it.
CA-125 levels have long been linked to ovarian cancer. However, because CA-125 can be high for a variety of reasons other than ovarian cancer, using it as a sole indicator of disease in the past has led to many false positives and unnecessary invasive procedures. This new study suggests that it is not just the level of CA-125 that can most effectively sound the alarm for cancer, but also how it rises over time. The numbers of false positives in this study were extremely low, with only 0.1% of the subjects incorrectly testing positive.
Because the study is relatively small, it is unlikely to spur any changes in screening recommendations for the time being. A similar study currently underway in the UK should have results from approximately 200,000 women by 2015.