Now, though, researchers say they have found a situation in Norway that has let them ask that question about breast cancer. And their new study, to be published Tuesday in The Archives of Internal Medicine, suggests that even invasive cancers may sometimes go away without treatment and in larger numbers than anyone ever believed.Interesting. While the results will need to be replicated given their extraordinary nature, if true it raises a couple of points.
The study was conducted by Dr. H. Gilbert Welch, a researcher at the VA Outcomes Group in White River Junction, Vt., and Dartmouth Medical School; Dr. Per-Henrik Zahl of the Norwegian Institute of Public Health; and Dr. Jan Maehlen of Ulleval University Hospital in Oslo. It compared two groups of women ages 50 to 64 in two consecutive six-year periods.
One group of 109,784 women was followed from 1992 to 1997. Mammography screening in Norway was initiated in 1996. In 1996 and 1997, all were offered mammograms, and nearly every woman accepted.
The second group of 119,472 women was followed from 1996 to 2001. All were offered regular mammograms, and nearly all accepted.
It might be expected that the two groups would have roughly the same number of breast cancers, either detected at the end or found along the way. Instead, the researchers report, the women who had regular routine screenings had 22 percent more cancers. For every 100,000 women who were screened regularly, 1,909 were diagnosed with invasive breast cancer over six years, compared with 1,564 women who did not have regular screening.
There are other explanations, but researchers say that they are less likely than the conclusion that the tumors disappeared.
The most likely explanation, Dr. Welch said, is that “there are some women who had cancer at one point and who later don’t have that cancer.”
First, it makes you wonder how many cancers that are "successfully treated" by doctors would have gone away on their own without any intervention. It also makes you wonder why exactly the cancer went away and if other patients could harness the body's natural ability to stop cancer.
Second, while an ounce of prevention might be worth a pound of cure, studies like this show that preventative medicine is spending resources on treating people that would have gotten better on their own. It is not clear then that prevention is nearly as cost effective as proponents would have you believe.
via NY Times