I know several women who discovered they had breast cancer much later than they ought to have, because they were refused access to screening, their doctors dismissed their concerns or their breasts were so dense that tumours were not easily detectable by ultrasound or mammogram.
And then, today I read in the Globe and Mail that a new study coming out of Norway, revealed that some cancers will disappear on their own and that more sophisticated testing, such as the MRI, can lead to “overdiagnosis”:
The study, published yesterday in the journal Archives of Internal Medicine, suggested breast-cancer screening may be leading to overdiagnosis, with about 22 per cent of cases likely to resolve themselves without treatment.
Once a breast cancer is found, however, it would currently be considered unethical not to treat it. So – if the theory is correct – large numbers of women may be having surgery, radiation, chemotherapy and other treatments that would never have been needed if their cancers had not been detected.
Radiation can damage the heart and coronary arteries. A previous randomized controlled trial showed that about one in 10 women who receive radiation for breast cancer will die from heart damage attributable to the treatment, he said.
In a telephone interview from Oslo, Dr. Zahl said that if he and his co-authors are correct, two women die from complications of breast-cancer treatment for every woman saved by screening.
“And that’s a very bad tradeoff.”
The study’s authors argue that, since it is considered unethical to treat cancer once it has been detected, more aggressive detection can lead to unnecessary treatment that may cause more harm than good.
I was feeling a little uneasy when I read this article and trying to articulate why, when I read a response from Dr. Amy Tuteur (thanks to Jenny for the link). Her last paragraph was the clincher for me:
Finally, and most importantly, there is no way to tell the difference on mammography, or by any other technique, between the cancers that will disappear and the ones that will go on and kill the woman. Without a practical way to separate those who need to be treated from those who do not, the finding is intriguing and worthy of further investigation, but cannot guide us in determining the best way to screen for breast cancer and the best way to treat it.
It’s hard, when reading this stuff, not to consider my own situation. My breast cancer was diagnosed after I found the big, hard lump in my right breast. The kind of cancer I have is aggressive, and by the time we found it, fairly advanced. If I had had an MRI and my tumour had been discovered before the cancer had spread to my lymph nodes, the chance of metastasis could have been much lower.
How would doctors know which cancers to ignore and which to treat?
Until we have the answers to those questions, this study seems to me to be meaningless.
And I hope it doesn’t used as a reason to deny tests to women who are high risk or who suspect they might have breast cancer.
Cross-posted to Not Just About Cancer.