To answer your questions:
1) Depending on the cause, it may take several weeks to months for gastritis to resolve.
2) A negative endoscopy in 2000 would make stomach cancer unlikely. However, to be sure, repeating the endoscopy, or obtaining an upper GI series can be considered.
Followup with your personal physician is essential.
This answer is not intended as and does not substitute for medical advice - the information presented is for patient education only. Please see your personal physician for further evaluation of your individual case.
Kevin, M.D.
kevinmd_b