Breast cancer study suggests watchful waiting, not surgery
Many women are receiving unnecessary treatment for a condition that is sometimes called Stage 0 breast cancer, a new Canadian study suggests.
Women who undergo single or double mastectomies or radiation as treatment for ductal carcinoma in situ (DCIS) do not appear to be increasing their chances of survival, the paper argues.
Most patients — nearly 97 per cent — are expected still to be alive 20 years after their diagnosis, based on the findings of the study done by researchers at Toronto’s Women’s College Hospital and the University of Toronto, and published in the journal JAMA Oncology.
While up to 3.3 per cent will die, aggressive early treatments do not appear to alter the course the disease takes, the scientists report.
With DCIS, cancerous cells are found in the milk ducts of the breast. The current approach is to remove the affected portion of the breast and treat with radiation to lower the risk the cancer will return or spread. But some women want more reassurance and opt for surgery to remove one or both breasts.
An editorial accompanying the article argues the findings should lead to a dialing back of the way women diagnosed with DCIS are treated.
“It’s not an emergency. It’s just not an emergency,” said Dr. Laura Esserman, lead author of the editorial.
“We need to stop the urgency, be more thoughtful, start generating different approaches, think about it as prevention.”
For Esserman, who is director of the University of California, San Francisco breast care centre, the findings support the notion some women with DCIS may not need surgery at all.
The right approach may be to actively monitor them, treating only if the cancer progresses — in the same way many prostate cancer cases are now handled, she said.
The lead author of the paper, Toronto breast cancer expert Dr. Steven Narod, isn’t necessarily advocating that approach.
He believes the death rate would be higher than 3.3 per cent if women with DCIS did not have surgeries to remove the cancerous cells — though how much higher would be a guess.
“The surgeons cure 97 per cent of it. If you did nothing ... we don’t know what would happen,” he said.
Narod’s research is what is called an observational study. It looked at the medical records of more than 100,000 women diagnosed with DCIS from 1988 to 2011, and assessed whether treatments had an impact and how many of them were still alive after 10 and 20 years.
The large numbers lend confidence to the findings. But an observational study cannot prove that one course of action is better than another.
The death rate at 10 years after diagnosis was 1.1 per cent, rising to 3.3 per cent at 20 years.
Esserman’s editorial noted that the 20-year rate is similar to what the American Cancer Society estimates is an average woman’s risk of dying of breast cancer in her lifetime.
The study shows, though, that there is a subset of women for whom the risk was much higher.
Women diagnosed with DCIS before the age of 35 had a mortality rate that was 17 times higher than would be expected for them in the nine years following their diagnosis. But only one per cent of the women in the study were diagnosed under the age of 35.