- NOTE: If archived sample was collected > 8 weeks prior to pre-registration (reg), is not available in a timely manner, or was collected outside of Mayo Clinic and considered unevaluable, then baseline EGD with primary tumor biopsy at Mayo Clinic must be performed unless clinically contraindicated; patient is allowed to enroll regardless of whether this Mayo Clinic tissue sample is evaluable; (Only 1 EGD with primary tumor biopsy performed at Mayo Clinic =< 8 weeks prior to pre-reg is required)