to ymav4294: ct scan frequency and pfs results, page-11

Oops yes your quite right aorou011 ca125 isn’t mentioned in the registration information. Should have looked first rather than assumed it would follow Can-003.

So if you look at studies around the timing of assessments for calculating PFS one idea that comes up is the notion that assessment interval not exceed the expected improvement in median PFS in the experimental versus control arm.

A wide interval does lead to an over estimation of clinical effect – but if you take a midpoint as your date this is likely cause underestimation.

What all this means is that it does make it harder to compare PFS estimates coming out of different studies because the assessment timing may be different. There are various people looking at this issue at the moment.

Where the problem really crops up is when asymmetry occurs between the arms. The intervention group might receive greater monitoring of symptoms and therefore at higher risk of receiving a off protocol ct scan. Hence reducing the PFS.

I would moderate my earlier post for providing wrong information if anyone thought it was serious enough - but presuming people read the whole thread – they can see how all our thinking evolved. Mine include – always learning – and making mistakes!

Your comment about OS is interesting. There is a much better relationship between PFS and OS in ovarian cancer compared with say breast cancer. But I would have thought it was too early and too small a sample for this now - but again should do some research before shooting from the hip.

Regards Southoz.