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Behind the Conflicting Headlines: What do the Results of Trials of Avastin for Ovarian Cancer Actually Show?

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Last month the results of two trials into the use of a drug called Avastin (also known as bevacizumab) for ovarian cancer were published. Confusingly, different media outlets have reported the results very differently. The Daily Mail and The Huffington Post UK reported it as a positive news story: "New drug can slow progress of ovarian cancer by up to six months" . In contrast, other outlets, such as in The Huffington Post Canada, said the results were disappointing. Since then, the drug has received approval from the European Medicines Agency for treating ovarian cancer.

Why did journalists interpret the results so differently? It seems to be down to whether the writer focused on how long the drug delays the tumour getting worse, or how long the drug increases life expectancy. It also depends upon which of the various analyses described in the trial results publications the writer focuses on.

Both the trials showed that adding Avastin to chemotherapy delays the tumour getting worse, which is good news. The trial carried out in the US (called GOG218) included only patients with advanced disease. They found that, on average, the drug delayed the tumour getting worse by four to six months. The other trial, led by the UK Medical Research Council (called ICON7), included a much broader range of women with ovarian cancer. In fact, two thirds of them had less advanced disease than those in GOG218. The ICON7 trial found that Avastin delayed the tumour getting worse by around two months. This increased to six months for women who had advanced disease.

It is currently less clear whether Avastin increases life expectancy. The GOG218 trial did not find that Avastin helped women with ovarian cancer to live for longer. However, the design of this trial meant that it was unlikely to be able to look at life expectancy. This is because many women in the control arm of the trial, who were not intended to receive Avastin, received it as part of their further treatment after their tumour got worse again. This could have masked any difference between the control group and the women who received Avastin as part of the trial.

The ICON7 trial should be able to tell us whether Avastin increases life expectancy, once the final results are analysed. However, not enough time has passed since women were given the drug to be able to draw any accurate conclusions yet. From the data currently available, it looks as though Avastin may increase the life expectancy of women with advanced disease by about eight months. But we still need to confirm this with longer-term data.

So we can't yet reliably say that Avastin does or does not increase life expectancy. We won't know whether this is true or not until the final results of the ICON7 trial are ready in 2013. What we can say now is that for women with advanced disease, the increase in life expectancy seen in the ICON7 trial is very encouraging. Avastin is the most promising new drug for treating ovarian cancer in more than 15 years. Nevertheless, we need to wait a little longer (until next year) to be sure. Before we change how all women with ovarian cancer are treated, we need to know more about who will benefit the most from Avastin.

We urgently need to improve how women with ovarian cancer are treated. I hope that further results from the ICON7 trial that are due out over the next year or so will bring us the knowledge to do this.

This blog was written on behalf of the Medical Research Council Clinical Trials Unit and the Chief Investigators of the ICON7 trial.