ppi before endoscopy

Hi,
   i have recently had an endoscopy which showed severe esophagitis. My question is that prior to endoscopy i was taking a ppi for 9 days or so. I have read that this may mask cancer if taken before endoscopy. There were biopsies done, crp and blood tests done and i am a thirty year old male, everything was normal.

I have been put on 40mg of nexium for 3 months but am worried that this may still mask something more serious if there was anything there in the first place. Would you consider me a low risk for cancer and is  it likely that the ppi use prior to endoscopy could have covered up something more serious?

Thanks