FACTBOX: Presidential candidate John McCain

(Reuters) - Republican nominee John McCain takes his turn on stage at the party's convention on Thursday to lay out why he should be elected U.S. president.

Here are some facts about the Arizona senator.

* If elected, McCain, who turned 72 on August 29, would be the oldest first-term U.S. president.

* McCain is the son and grandson of four-star admirals and followed in their footsteps by attending the U.S. Naval Academy, where he led what he called a group of troublemakers.

* Shot down during a combat mission over Vietnam in 1967, he spent 5 1/2 years as a prisoner of war, including two years in solitary confinement, and was subjected to beatings and torture. In the Senate, he has been a critic of harsh interrogation techniques such as "waterboarding," the simulated drowning of terrorism suspects. McCain turned down a chance to leave prison before comrades who had entered earlier.

* In the past 15 years, McCain has been treated four times for skin cancer. The most serious case was in 2000 when he underwent surgery on his face for melanoma, leaving him with a bulge and a long scar on the left side of his face. He has had regular medical checks and been cancer free since then.

* First elected to the U.S. House of Representatives in 1982, McCain won the first of four Senate terms in 1986.

* McCain has been married to Cindy Hensley McCain since 1980. He was married to his first wife Carol, from 1965-1980. He has seven children.

(Compiled by Deborah Charles and Patricia Zengerle, editing by Jackie Frank)