Early treatment based on CA125 levels alone versus delayed treatment based on conventional clinical indicators

Is it more effective to give chemotherapy when CA125 starts to rise?

What was this study about?

Ovarian cancer is the fourth most common cancer in women. Treatment involves surgery to remove the cancer, followed by chemotherapy. Many women have a good response to chemotherapy, but in some women the cancer does return.

This trial investigated the best time to give chemotherapy to women who have recurring ovarian cancer with raised levels of CA125. It was hoped that treating patients earlier with chemotherapy can improve survival and quality of life for women with ovarian cancer.

In this study, women who had raised markers were randomly placed into two groups: in one group women received chemotherapy immediately when they had no symptoms. In the second group, treatment was delayed. Patients in this group continued to have their levels of CA125 monitored and were given chemotherapy when they developed symptoms or the reappearance of cancer was detected by physical examination.

What difference did this study make?

Unfortunately, the OV05 study found that treating patients earlier with chemotherapy did not improve survival or quality of life for women with ovarian cancer. 

Researchers found that women in the first group (who were treated as soon as their blood showed an abnormally high level of CA125) had chemotherapy 5 months earlier than those who were treated later. They did not live any longer than women who were treated only when they had symptoms of cancer, or when doctors could see other signs that their cancer had come back.  It was also found that women who were treated as soon as their blood showed an abnormally high level of CA125 needed re-treatment for the second relapse of their ovarian cancer 5 months earlier. Additionally, starting treatment earlier did not improve women's quality of life.

Type of study

Randomised trial

Contact details


Who funded the study?

The trial was supported by the Medical Research Council and the National Cancer Research Network. It was a collaborative trial with the European Organisation for Research and Treatment of Cancer (EORTC 55955).

When did it take place?

The trial completed recruitment of 1,442 women in October 2005.

Where did it take place?

Many hospitals throughout Europe, Russia and South Africa took part.

Who was included?

Women who had either ovarian, fallopian tube or primary peritoneal cancer who had complete remission with a normal CA125 marker after first line chemotherapy treatment.