Both have a problem that runs counter to everything people have been told about cancer: They are finding cancers that do not need to be found because they would never spread and kill or even be noticed if left alone. That has led to a huge increase in cancer diagnoses because, without screening, those innocuous cancers would go undetected.
At the same time, both screening tests are not making much of a dent in the number of cancers that are deadly. That may be because many lethal breast cancers grow so fast they spring up between mammograms. And the deadly prostate ones have already spread at the time of cancer screening. The dilemma for breast and prostate screening is that it is not usually clear which tumors need aggressive treatment and which can be left alone. And one reason that is not clear, some say, is that studying it has not been much of a priority.
“The issue here is, as we look at cancer medicine over the last 35 or 40 years, we have always worked to treat cancer or to find cancer early,” Dr. Brawley said. “And we never sat back and actually thought, ‘Are we treating the cancers that need to be treated?’ ”
The very idea that some cancers are not dangerous and some might actually go away on their own can be hard to swallow, researchers say.
“It is so counterintuitive that it raises debate every time it comes up and every time it has been observed,” said Dr. Barnett Kramer, associate director for disease prevention at the National Institutes of Health.
It was first raised as a theoretical possibility in the 1970s, Dr. Kramer said. Then it was documented in a rare pediatric cancer, but was dismissed as something peculiar to that cancer. Then it was discovered in common cancers as well, but it is still not always accepted or appreciated, he said.
But finding those insignificant cancers is the reason the breast and prostate cancer rates soared when screening was introduced, Dr. Kramer said. And those cancers, he said, are the reason screening has the problem called overdiagnosis — labeling innocuous tumors cancer and treating them as though they could be lethal when in fact they are not dangerous.
“Overdiagnosis is pure, unadulterated harm,” he said.
Dr. Peter Albertsen, chief and program director of the urology division at the University of Connecticut Health Center, said that had not been an easy message to get across. “Politically, it’s almost unacceptable,” Dr. Albertsen said. “If you question overdiagnosis in breast cancer, you are against women. If you question overdiagnosis in prostate cancer, you are against men.” ... http://www.nytimes.com/2009/10/21/health/21cancer.html