CBT for cancer patients

Hi,  my mum had stage 4 ovarian cancer diagnosed and treated in 2016.  Shes been doing amazing with CA125 levels consistently below 15, until the past couple of months when they've started to rise again.  We're currently awaiting a CT and there is obviously lots of uncertainity and potentially hard times to come.  What she really struggles with is the mental side of it all.  She physically well at the moment and symptom free but psychologically she's really struggling to get passed all the negative thoughts she has about the future.  I just wondered if anyone knew of any online cbt exercises for cancer patients?  I'm looking into getting her counselling and she does the headspace app, but I'm just wondering if anyone knows of anything online for cancer patients?  Thanks so much.