Some types of cancer can be found before the cancer symptoms appear. Checking for cancer or for conditions that may lead to cancer in people with no symptoms is called screening. Screening in the general population or in people with specific genetic risks can help doctors find and treat some types of cancer early. Screening often improves survival.
If all ovarian cancers were found at an early stage, nearly 90% of women would live at least five years after their cancer diagnosis. Unfortunately, most women are diagnosed with advanced stage (stages III or IV) ovarian cancer, with an overall five-year survival rate of 30%.
Three very large ovarian cancer clinical studies screened more than 350,000 women using a blood test to detect the tumour marker CA-125 (a molecule present on cancer cells) and/or transvaginal ultrasound (during which a probe is placed in the vagina). Unfortunately, these studies showed that these screening methods did not reliably detect ovarian cancer or lead to early stage detection. In fact, the studies actually found a harmful effect of CA-125 and transvaginal ultrasound screening: women who had positive screening tests but no ovarian cancer were given additional tests that caused anxiety and unnecessary surgery. Attempts at ovarian cancer screening in high risk women such as those with inherited BRCA1 or BRCA2 gene mutations have also been unsuccessful.
Therefore, currently no screening tests effectively detect ovarian cancer at an early stage. The most effective way to reduce the impact of ovarian cancer is through prevention in high risk women, especially women with inherited mutations in the BRCA1 or BRCA2 genes.