Untreated cancer can go away, study says

If proven, watchful waiting could help in breast cancer

November 25, 2008|By New York Times News Service

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 might sometimes go away without treatment - and in larger numbers than 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 A. Smith, director of breast cancer screening at the American Cancer Society.

But others, including Robert M. Kaplan, the chairman of the department of health services at the School of Public Health at the University of California, Los Angeles, are persuaded 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 if 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 incidents of cancer.

A leading alternative explanation for the results is that the women having regular scans used hormone therapy for menopause and the other women did not. But the researchers calculated that hormone use could account for no more than 3 percent of the effect.

Or perhaps the screened women had a higher cancer risk to begin with. But, the investigators say, the groups were remarkably similar in their cancer risk factors.

Smith, however, said the study was flawed and the interpretation was incorrect. Among other things, he said, one round of screening in the first group of women would never find all the cancer that regular screening had found in the second group. The reason, he said, is that mammography is not perfect, and cancer that is missed on one round of screening will be detected on another.

But Welch said that he and his colleagues considered that possibility, too. And, he said, their analysis found subsequent mammograms could not make up the difference.

Kaplan is already thinking of how to replicate the result. One possibility, he said, is to do the same sort of study in Mexico, where mammography screening is now being introduced.

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