American Cancer Society's Guidelines for screening and surveillance
for early detection of colon polyps and cancer suggest that persons
of average health and who are 50 years of age or older
should be screened for colon cancer. You could also be at risk if there is:

• Personal history of colorectal cancer
• Personal history of polyps
• Family history of colorectal polyps or cancer
• Personal history of inflammatory bowel disease
  (ulcerative colitis or crohn's colitis)

The American Society for Gastrointestinal Endoscopy’s guidelines for screening
and surveillance for early detection of Barrett’s esophagus
and cancer of the esophagus include:

• Regular or daily heartburn for over 5 years
• Waking during the night because of heartburn
• Difficulty swallowing
• Smoke cigarettes and drink alcohol excessively
• Male, caucasian, 40 years of age or older with a history of reflux