Cancers Can Vanish Without Treatment, but How?

By GINA KOLATA
Published: October 26, 2009

Call it the arrow of cancer. Like the arrow of time, it was supposed to point in one direction. Cancers grew and worsened.

But as a paper in The Journal of the American Medical Association noted last week, data from more than two decades of screening for breast and prostate cancer call that view into question. Besides finding tumors that would be lethal if left untreated, screening appears to be finding many small tumors that would not be a problem if they were left alone, undiscovered by screening. They were destined to stop growing on their own or shrink, or even, at least in the case of some breast cancers, disappear.

“The old view is that cancer is a linear process,” said Dr. Barnett Kramer, associate director for disease prevention at the National Institutes of Health. “A cell acquired a mutation, and little by little it acquired more and more mutations. Mutations are not supposed to revert spontaneously.”

So, Dr. Kramer said, the image was “an arrow that moved in one direction.” But now, he added, it is becoming increasingly clear that cancers require more than mutations to progress. They need the cooperation of surrounding cells and even, he said, “the whole organism, the person,” whose immune system or hormone levels, for example, can squelch or fuel a tumor.

Cancer, Dr. Kramer said, is a dynamic process.

It was a view that was hard for some cancer doctors and researchers to accept. But some of the skeptics have changed their minds and decided that, contrary as it seems to everything they had thought, cancers can disappear on their own.

“At the end of the day, I’m not sure how certain I am about this, but I do believe it,” said Dr. Robert M. Kaplan, the chairman of the department of health services at the School of Public Health at the University of California, Los Angeles, adding, “The weight of the evidence suggests that there is reason to believe.”
This is interesting. The Brits (among others) are examining this idea. It has a lot of implications for screening programs. In the U.S., breast cancer screening is promoted very widely and cancers are treated very aggressively. This results in fewer breast cancer deaths for American women but also in a high rate of false positives and perhaps unnecessary treatment for many women.

It may be that cancers in some locations (like the breast or prostate) should simply be carefully watched if they occur in individuals over 50.

NYT