(CNN) -- Meghan McCain was on the talk-show couch, being grilled by the hosts of "The View." Does it bother her to hear jokes about her father's age? Megan, 23, started chuckling, and allowed, "He IS old!" Tension was replaced by laughter. But that was summer. These days, for Republican Sen. John McCain, age is no laughing matter.

Republican presidential nominee Sen. John McCain and wife Cindy greet supporters Monday in New Mexico.

Age as political issue has become a reality the McCain campaign does indeed have to face. McCain turned 72 in August, which would make him the oldest man to begin a first term as president -- three years older than Ronald Reagan.

Clips of McCain making supposed age-related gaffes circulate on the Internet. Last month, Sen. Claire McCaskill, a Missouri Democrat and a supporter of Democratic candidate Sen. Barack Obama, said McCain's age and skin cancer history were fair game as a campaign issue. "We're talking about a reality here that we have to face." A few days ago, a liberal activist group, Brave New Films, ran a full-page ad in the New York Times, accompanied by a petition signed by more than 2,700 physicians calling on McCain to release his full medical records.

All this skates over the fact that McCain already allowed reporters a peek at eight years worth of health records, dating back to 2000, while Obama has released a one-page summary from his doctor. McCain spokesman Tucker Bounds said it's a double standard. "The arbiters of this election are not demanding the same level of disclosure about Sen. Obama. He's essentially running on a doctor's note. I had a harder time getting out of high school math class." Watch Dr. Sanjay Gupta report on the age and health questions surrounding McCain »

McCain bristles when it is suggested that he might lack youthful vigor. Early in the primaries, he faced a blunt question from a New Hampshire teenager. Was he worried he would get Alzheimer's disease or die in office? "I'm very active," McCain shot back. "People will judge by the vigor and enthusiasm associated with our campaign. I've out-campaigned my opponents, every race I've ever been in." He ended with a joke. "Thanks for the question, you little jerk!"

Fit To Lead Dr. Sanjay Gupta investigates presidential health

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In an effort to dispel health concerns, this spring McCain's campaign allowed select reporters, including CNN's Dr. Sanjay Gupta, a look at more than 1,100 pages of medical records. In a teleconference with reporters, Dr. John Eckstein, McCain's personal physician, declared him to be in excellent health. "I and my colleagues can find no medical reasons or problems that would preclude Sen. McCain from fulfilling all the duties and obligations of the president of the United States."

Since 1993, McCain has had four skin cancers removed. McCain's biggest health scare came in December 2000, when he was found to have a Stage 2 melanoma on his left cheek. The cancer was about as wide as a dime and a little thicker than a nickel. By today's standards, his surgeons took an extremely aggressive approach, removing more than 30 lymph nodes even though a test showed the cancer had not spread. McCain's surgeon, Dr. Michael Hinni, said they simply wanted to err on the side of caution.

McCain's records might be an open book compared to Obama's, but his campaign is a long way from full disclosure. They gave reporters three hours to look through the massive stack of paperwork, and didn't allow pictures or photocopies.

Dr. Wendy Epstein is a dermatologist who signed a petition calling on McCain to release all his records to the public. "Anybody running for the president gives up their right for personal privacy. Their health is my concern." Epstein, who said she's a registered Democrat married to a Republican, said it's not clear whether McCain's most severe melanoma was related to the others, a so-called metastasis. "We need to know: Did this melanoma spread, or didn't it? And that can only be answered by an independent group of dermatopathologists, looking at slides."

Hinni and McCain's dermatologist, Dr. Suzanne Connolly, said it was not a gray area: The cancer was clearly Stage 2. Gupta, one of few reporters to see the pathology report, said the file backs up that assertion. Eight years post-removal, Connolly said the chance of a recurrence is less than 10 percent. Bounds, the McCain spokesman, said it is "unacceptable" that doctors who haven't examined McCain are questioning his own physicians. "This is a highly respected team of doctors he's been working with. They have concluded he is in perfect health." Coming this weekend on CNN: Fit to Lead

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Dr. Thomas Perls, a geriatrician who has conducted some of the most extensive research on aging, said advantages ranging from good health care to good genes work in McCain's favor. McCain likes to point to his mother, Roberta, still spry and giving interviews at age 96. Perls agreed that longevity runs strongly in families. "Having a 96-year-old mom who's in pretty good shape definitely bodes well for him, and not only for his ability to get to older years, but to spend a greater period of that time in good health."

Perls' greater concern is mental sharpness. "While we have some data about [McCain's] cholesterol and some other physical exam features, we don't really have good testing of his brain," said Perls. Studies based on census data show that by age 79, one in six Americans is suffering from cognitive decline, and that each year 12 percent of that group progress to full-blown dementia.

To be clear, those are simply averages for the population as a whole, and there is no indication that McCain is suffering a cognitive decline. Voters might take heart from other leaders who served well into their golden years. Israel's Golda Meir was 76 by the time she left office. French President Charles de Gaulle was 78, and Nelson Mandela led South Africa until he was 80.

Or McCain might take a page from Ronald Reagan, who was 73 when he ran for re-election in 1984. During a televised debate against Walter Mondale, then 56, Reagan famously began by saying, "I will not make age an issue of this campaign. I will not hold my opponent's youth and inexperience against him." The audience laughed. Reagan went on to win the election.

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