Study says some cancers go away without treatment

Cancer researchers have known for years that it was possible in rare cases for some cancers to go away on their own. There were occasional instances of melanomas and kidney cancers that just vanished. And neuroblastoma, a very rare childhood tumor, can go away without treatment.

But these were mostly seen as oddities — an unusual pediatric cancer that might not bear on common cancers of adults, a smattering of case reports of spontaneous cures. And because almost every cancer that is detected is treated, it seemed impossible even to ask what would happen if cancers were left alone.

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 today 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.

At the moment, the finding has no practical applications because no one knows whether a detected cancer will disappear or continue to spread or kill.

And some experts remain unconvinced.

"Their simplification of a complicated issue is both overreaching and alarming," said Robert Smith, director of breast-cancer screening at the American Cancer Society.

But others, including Robert Kaplan, the chairman of the department of health services at the School of Public Health at the University of California, Los Angeles, are convinced by the analysis. The implications are potentially enormous, Kaplan said.

If the results are replicated, he said, it could eventually be possible for some women to opt for so-called watchful waiting, monitoring a tumor in their breast to see whether it grows. "People have never thought that way about breast cancer," he added.

Kaplan and his colleague, Dr. Franz Porzsolt, an oncologist at the University of Ulm, said in an editorial that accompanied the study, "If the spontaneous-remission hypothesis is credible, it should cause a major re-evaluation in the approach to breast-cancer research and treatment."

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 routine screening.

There are other explanations, but researchers say that they are less likely than the conclusion that the tumors disappeared.

The most likely explanation, Welch said, is that "there are some women who had cancer at one point and who later don't have that cancer."

The finding does not mean that mammograms caused breast cancer. Nor does it bear on the question of whether women should continue to have mammograms, because so little is known about the progress of most cancers.

Mammograms save lives, Smith said. Even though they can have a downside — most notably the risk that a woman might have a biopsy to check on an abnormality that turns out not to be cancer — "the balance of benefits and harms is still considerably in favor of screening for breast cancer," he said.

But Dr. Suzanne Fletcher, an emerita professor of ambulatory care and prevention at Harvard Medical School, said that it was also important for women and doctors to understand the entire picture of cancer screening. The new finding, she said, was "part of the picture."

The study's design was not perfect, but researchers say the ideal study is not feasible. It would entail screening women, randomly assigning them to have their screen-detected cancers treated or not, and following them to see how many untreated cancers went away on their own.

But, they said, they were astonished by the results.