Can surgery spread breast cancer?
Surgery to take out a lump or remove a breast may make breast cancer spread more quickly, according to a new international study.
But the study in the latest issue of the European Journal of Cancer has come under attack from an Australian cancer expert, who says the evidence is lacking.
The report's lead author, Professor Michael Baum of the Portland Hospital in London, says that having surgery for breast cancer might cause tumours to grow and proliferate, especially in young patients whose cancer isn't advanced.
Baum says surgery to remove a primary tumour could kick-start the growth of metastases, cancers that spread to other parts of the body, which may otherwise have remained dormant.
This, he says, is because the surgery may stimulate angiogenesis, the formation of new blood vessels, which feeds tumours.
Tumour growth could also be stimulated by the production of growth factors as part of the post-operative wound healing process, Baum says.
"A likely trigger for 'kick-starting' the growth of micro-metastases could be the act of surgery itself," he writes.
An old theory
Australian researcher Professor John Boyages, director of the NSW Breast Cancer Institute in Sydney, says surgery can worsen the condition of animals with breast cancer. And researchers have been trying to prove if this is so in humans for the past 15 years.
"But every time we look at the data there's nothing there," he says.
Boyages says separate research published in the Journal of the National Cancer Institute on 2 February provides evidence that having surgery for breast cancer does not reduce survival rates.
The research reviewed nine studies involving almost 4000 breast cancer patients and concludes that women who have chemotherapy first do not do any better than women who have surgery first in terms of survival or the progression of their disease.
"The latest results showing a meta-analysis of giving chemo first or surgery first has put the issue to bed because it doesn't show people having chemo first have better survival," he says.
Boyages says it's important to "keep an open mind" about the issues Baum raises.
"But you can't just say surgery is bad for you because it sends a message to the community that maybe you should leave your cancer," he says.
Too risky to cancel surgery
Professor Alan Coates, chief executive officer of the Cancer Council Australia, says surgery remains the mainstay of primary cancer treatment and in most cases the benefits outweigh any risks.
"To the question of does surgery unfavourably perturb the natural history of early breast cancer ... the answer quite clearly is 'yes'," he says.
"The only question is, is that a big enough risk to outweigh the benefits of surgery, and in which cases?"
A variation on the theory suggests that it isn't the surgery but the lowered immune response after anaesthesia that might make the cancer worse, he says.
Coates says the study could lead to better-targeted treatments with anti-angiogenic or growth factor-suppressing therapy to overcome the effects of surgery.
"But surgery is a very important part of treatment for breast cancer and women shouldn't be persuaded from having surgery," he says.