Do we know enough about presidential health?

In this Dec. 17, 2001 file photo, dark spots are visible on President Bush's cheeks and temple after it was disclose that the president had four lesions removed from his face, including two that are pre-cancerous but not a threat to the president's health. Woodrow Wilson's secret stroke. Grover Cleveland's secret cancer surgery. Franklin D. Roosevelt's secretly worsening heart disease at the world-changing Yalta Conference. Notice a lot of secrets? (AP Photo/J. Scott Applewhite)