Breast cancer screening for women under 50 should stop in
light of growing questions around how beneficial the practice
is, health researchers say.
Dr Caroline Shaw and Associate Professor Diana Sarfati from
University of Otago Wellington have written blogs that say
the benefits of breast cancer screening is much less
favourable than previously thought due to over-detection of
cancers and other issues.
The screening could detect cancers that would never cause a
problem in a person's lifetime, the blog said.
"This is completely counter to how most people think about
cancer, but this phenomenon is seen in all cancers (and many
other medical conditions) we screen for.
"The problem is that when we identify a breast cancer through
screening we can't always tell if it is a cancer that is
going to cause a problem or not. So we have to treat them
Treatments, such as radiotherapy, could be "mutilating,
painful and involve long term side effects", the blog said.
"Thus, any potential benefits of screening have to be weighed
up against the harms of unnecessary mastectomies, side
effects from the surgery, chemotherapy and radiotherapy. Not
to mention stress and anxiety."
Advances in breast cancer treatment since randomised control
trials (RCTs) of screening in the 1970s and early 80s had
been substantial, and consequently survival and mortality had
improved considerably, the researchers said.
The extent of over diagnosis - the key harm of breast cancer
screening - was hotly contested, Dr Shaw and Professor
"It is not disputed that there is over diagnosis and over
treatment, but the extent of and best way to measure over
diagnosis are not clear."
Screening in women under 50 was not recommended by any of the
independent bodies who had reviewed the evidence and no
screening programmes in the United Kingdom, Canada or
Australia started under 50.
"The balance of benefits and harms in this age group is not
favourable. In New Zealand we need to stop screening women
under 50 and start being more honest about the lack of
clarity about the evidence for screening in older women," Dr
Shaw and Professor Sarfati said.
Breast Cancer Foundation chief executive Evangelia Henderson
strongly disagreed with the research and said breast cancer
detections in women under 50 had saved hundreds of lives.
"In 2012 we had 423 women aged between 45 and 49 diagnosed in
New Zealand with breast cancer, and that's invasive breast
cancer we're talking about."
The foundation strongly supported screening and promoted the
procedure for women aged 40, she said.
"Why not have screening to save a life?"
The five-year survival of a woman whose cancer was diagnosed
through a mammogram 95 per cent and the five-year survival
rate of a woman who was diagnosed through feeling a lump, was
73 per cent, Ms Henderson said.
"So you can already see what early detection does - it
improves your survival."
She acknowledged that the screening was not advanced enough
to detect which cancers were going to become potentially
deadly and which were not.
But the choice was to have screening and treat any cancers
detected or take a chance that the cancer was not serious.
"It's all very well being a researcher and being driven by
numbers, but actually, people's lives are more important."
- Rebecca Quilliam of APNZ