There's a one-in-four chance that Sen. John McCain will die in the next four years, according to a contested interpretation of risks posed by the presidential candidate's history of skin cancer.
"His mortality risk translates to 22 percent over a first term," said John Alam, a biotechnology consultant and former cancer researcher who crunched the numbers on McCain's cancer history.
That figure is roughly twice the death risk of a white male of McCain's age, but without McCain's past melanoma. Some researchers, however, think Alam's model fails to account for McCain's continued health.
"If after five years there's no recurrence, his chance of survival for the next five years and the remainder of his life are significantly increased," said Stanley Leong, a University of California, San Francisco oncologist whose research was cited by Alam in the estimate, published today in The Lancet.
That a metastatic skin cancer removed from McCain's left temple in 2000
has not reappeared is among the limited health information currently known about the candidate, who has been criticized for failing to disclose his complete medical records.
A statement prepared by Mayo Clinic doctors is available on McCain's website and includes basic information about that melanoma — enough for Alam to plug the figures into a standard model of post-melanoma mortality risk prediction.
The model was developed in 1996, and uses four variables: the age and sex of a cancer patient, as well as the site of the tumor and its dimensions. McCain was 64 when the lesion was found; it was thick and located on his temple, both of which place him in the model's high-risk category. Alam calculated that McCain had a 12 percent annual chance of dying, some four times higher than the average white male of McCain's age.
But doctors have not found evidence of cancer in tests of McCain's
sentinel lymph nodes, which are used as early warning signs of recurrence. Such tests didn't exist when Alam's model was developed;
using sentinel lymph node research authored by Leong, he accounted for these by halving McCain's annual mortality risk to 6 percent.
"You can go a long time with no sign of the melanoma being around, and then it comes back," said Alam.
Leong, however, said that the highest risk of melanoma recurrence exists in the several years following its initial diagnosis and removal. Referring to newer mortality risk models that emphasize the early years of melanoma recurrence, he said that Alam should have reduced McCain's risk even further.
"We never say a patient will be cured," said Leong, but called McCain's continued health "very encouraging."
But Alam said that newer models don't yet have reliable long-term cancer survival data of the sort needed to make sense of McCain's situation.
Potentially complicating the discussion is Alam's admitted political and financial support of McCain's opponent, Senator Barack Obama. Alam insisted that his politics may have influenced his decision to analyze McCain's records, but not the analysis itself.
"The facts about the risk need to be on the table. My goal was to provide objective evidence of what the mortality risk is," he said. "My politics have no bearing on the facts."
Lynn Schuchter, a University of Pennsylvania oncologist who developed the original model used by Alam, agreed with both Alam and Leong: most recurrences do take place in the first five years following an initial skin cancer diagnosis, she said, but that's not a hard-and-fast rule.
"The fact that he's seven or eight years out is a good sign," she said, "but he's not out of the woods."
U.S. Senator John McCain and risk of melanoma-associated mortality (The Lancet) (.pdf)
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