Friday, October 24, 2008

Estimating the Risk of McCain's Deadly Cancer Relapse

Interesting article in "The Lancet" followed by a piece in "New Scientist" on McCain's risk of melanoma recurrence within the four-year term.
Even though McCain's risk of recurrence is lower than his chances of becoming president elect, the numbers are striking...

"John Alam, a Cambridge, Massachusetts, physician with 17-years in clinical research who now works as a biotechnology consultant, estimates that Senator John McCain has a 6% risk of dying of a melanoma recurrence each year – or about 22% over four years. "There is a one-in-four to one-in-five chance that he would not survive a first term," he told New Scientist.

This is higher than the estimate of McCain's physician at the Mayo Clinic, who previously told reporters that he had a less than 10% chance of deadly relapse. On the other end of the scale, a group of physicians – and Obama supporters – has called on McCain to release more health records, claiming that his risk of relapse could be higher than 60%.

Alam's estimate is based on studies of the survival rates of others with melanoma, where the patients were grouped by the size and location of their tumour, their gender and age. His estimate – which is no more than an educated guess, of course – falls between the previous estimates of 10 and 60% for one important reason.

Many of the prognostic models that others have cited are based on patient studies that did not perform a sentinel lymph node (SLN) biopsy, a relatively new procedure that attempts to determine whether a tumour has spread to lymph nodes that serve as a cellular superhighway for aggressive tumours.

If the biopsy turns up no melanoma after surgery, patients are at a far lower risk of relapse and mortality than patients who are SLN-positive, according to two recent clinical studies.

However, some dermatologists worry that failing to detect melanoma in the biopsy can lead to false negatives and an underestimate of relapse risk. However, the procedure has become routine in patients with more advanced melanomas, such as McCain's, Alam says.

McCain, according to records posted on his campaign website, was SLN-negative when doctors performed the biopsy in August 2000, Alam writes in a short letter to The Lancet.

Alam says he performed the analysis independent of the Obama campaign. "Because the analysis is an objective, evidence-based analysis, I believe my having contributed has no bearing on the results of the analysis," he adds.

For comparison, a quick web search reveals the odds of dying in the US of other causes, natural and unnatural:

* Heart disease (lifetime) 1 in 5
* Poisoning (lifetime): 1 in 180
* Firearm (lifetime): 1 in 324
* Car accident (lifetime): 1 in 247
* Bicycle accident (lifetime): 1 in 4,472
* Defenestration (lifetime): 1 in 6,422
* Venomous plants and animals (lifetime): 1 in 46,539
* Legal execution (lifetime): 1 in 72,494
* Lightning (lifetime): 1 in 81,949
* Fireworks (lifetime): 1 in 1,884,832
* Shark (annual): 1 in 8,000,000

Journal reference: The Lancet (vol 371, p 1462)


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