blog
Out of context: Reply #18771
- Started
- Last post
- 76,739 Responses
- ********0
Lowell came in looking like the Cheshire Cat,” Myhrvold recalled. “He said, ‘I have a question for everyone. You have a tumor, and the tumor becomes metastatic, and it sheds metastatic cancer cells. How long do those circulate in the bloodstream before they land?’ And we all said, ‘We don’t know. Ten times?’ ‘No,’ he said. ‘As many as a million times.’ Isn’t that amazing? If you had no time, you’d be screwed. But it turns out that these cells are in your blood for as long as a year before they land somewhere. What that says is that you’ve got a chance to intercept them.”
How did Wood come to this conclusion? He had run across a stray fact in a recent issue of The New England Journal of Medicine. “It was an article that talked about, at one point, the number of cancer cells per millilitre of blood,” he said. “And I looked at that figure and said, ‘Something’s wrong here. That can’t possibly be true.’ The number was incredibly high. Too high. It has to be one cell in a hundred litres, not what they were saying—one cell in a millilitre. Yet they spoke of it so confidently. I clicked through to the references. It was a commonplace. There really were that many cancer cells.”
Wood did some arithmetic. He knew that human beings have only about five litres of blood. He knew that the heart pumps close to a hundred millilitres of blood per beat, which means that all of our blood circulates through our bloodstream in a matter of minutes. The New England Journal article was about metastatic breast cancer, and it seemed to Wood that when women die of metastatic breast cancer they don’t die with thousands of tumors. The vast majority of circulating cancer cells don’t do anything.
“It turns out that some small per cent of tumor cells are actually the deadly ones,” he went on. “Tumor stem cells are what really initiate metastases. And isn’t it astonishing that they have to turn over at least ten thousand times before they can find a happy home? You naïvely think it’s once or twice or three times. Maybe five times at most. It isn’t. In other words, metastatic cancer—the brand of cancer that kills us—is an amazingly hard thing to initiate. Which strongly suggests that if you tip things just a little bit you essentially turn off the process.”