"Overtreatment of Stage 0 Breast Cancer DCIS"
The whole point of cancer screening is to detect
life-threatening disease at an earlier, more curable stage.
So an effective cancer-screening program would therefore increase
the incidence of cancer detected at an early stage
because you'd find all those tiny cancers you would have missed before,
and therefore decrease the incidence of cancer presenting at a late stage
because you would have cut out all the little cancers you found,
pulling them out of circulation.
But that's not what appeared to happen with mammograms.
As mammography ramped up in the '80s,
the first part happened, the diagnosis of early cancers shot up.
And so what we'd like to see is like a mirror image of this
going the other way for late stage cancers.
If you caught it early, it wouldn't be around for late, but that didn't happen.
Late stage cancer incidence didn't seem to drop much at all.
Another way to look at this is to compare mammogram rates around the country.
The more mammograms you do, the more heavily screened the population is,
the more early cancers you pick up. Great.
And late advanced disease should go down, too, right, but it doesn't.
We're taking all these early cancers out of circulation—surgery, radiation—
so there should be about the same number fewer late stage cancers found,
but that didn't happen.
Mammograms catch a lot of small cancers, but with no concomitant decline
in the detection of larger cancers that would explain this.
The more mammograms you do, the more cancer you find,
but death from breast cancer doesn't seem to change much.
Wait a second.
You just cut out tens of thousands of cancers;
why aren't there that many fewer women dying?
Together these findings suggest widespread overdiagnosis,
meaning cancer picked up on mammogram that would have never progressed
to the point of presenting during the woman's lifetime,
and so wouldn't even have been noticed or caused any harm
had it never been picked up at all.
So if removing all these early ones didn't lead to that many fewer late ones,
that suggests that most would have never progressed during that time
or even go away on their own.
That could explain almost all that increase in incidence,
and indeed, many invasive breast cancers detected
by repeated mammography screening do not persist to be detected later,
suggesting that the natural course of many of the mammogram-detected
invasive breast cancers is to spontaneously regress, spontaneously disappear.
We've known for more than a century that even serious metastatic breast cancer
can sometimes just spontaneously go away.
The problem is that you can't tell which is which,
so if you find it, the natural inclination is to treat it,
which can be especially tricky for ductal carcinoma in situ, DCIS,
so called stage zero breast cancer.
This is what it looks like.
"Ductal" means in the breast ducts, "carcinoma" means cancer,
and "in situ" means in place, in position, not spreading outside the duct.
And it can create these tiny calcifications
that can be picked up on mammogram.
The whole point of mammograms was to identify early invasive disease,
so the large numbers of DCIS they found were unexpected, unwelcome.
Prior to the advent of mammogram screening, DCIS made up
approximately 3% of breast cancers detected,
but now accounts for a significant chunk.
The cells look like invasive cancer,
and therefore the presumption was made that these lesions
were the precursors of cancer, stage zero cancer, and that
early removal and treatment would reduce cancer incidence and mortality.
However, long-term population studies have demonstrated
that the surgical removal of 50,000 to 60,000 DCIS lesions annually
has not been accompanied by a reduction
in the incidence of invasive breast cancers.
This is in contrast to our experience with removing colon polyps with colonoscopy,
or precancerous cervical lesions thanks to pap smears,
in which the removal of precursor lesions
has led to a decrease in the incidence of colon and cervical cancer.
Those are cancer screening programs that work.
Radiologists argue that overdiagnosis
isn't so much the problem as overtreatment.
Yeah, it sucks to get a breast cancer diagnosis
even though it would have never hurt you,
but you don't know that at the time,
so most women undergo aggressive surgical and radiation treatment.
Yeah, but if you compare the 10-year breast cancer survival for women
with low grade DCIS among those who chose not to go to surgery at all?
1.2% of them died of breast cancer within a decade.
But in that same decade, those that went to surgery instead
for a lumpectomy or a full mastectomy to cut it out, 1.4% died from breast cancer.
So surgery appeared to make no difference.
That's why there are currently randomized controlled trials to put it to the test,
but it's incredibly difficult to convince a patient with DCIS
not to just want to get it cut out.
The fear of cancer paralyzes patients,
who may resort to drastic excessive measures
like getting a double mastectomy.
How can we prevent that? How about we change its name?
A National Cancer Institute panel has recommended
dropping the "carcinoma" part.
Let's just call it an indolent lesion of epithelial origin;
use language that engenders less fear.
How bad can an IDLE tumor be?
Another option to avoid this dilemma is just not get screened in the first place,
but women aren't typically told about any of this.
Less than 1 in 10 women were aware that mammograms
carried any potential harms at all,
and more than 9 out of 10 were unaware
that some breast cancers never cause problems.
Few were told about DCIS, but when informed about it,
most wished they were told before they signed up.
Once a cancer is detected, it is currently not possible to distinguish
life-threatening from potentially harmless cases.
Therefore, overdiagnosis can only be avoided
by abstaining from routine mammograms altogether.
That's how this researcher explained her own decision away from screening.
Worried by the possibility that she could be seriously harmed
by the treatment of a cancer that would never have affected her health,
and given that the only way to avoid opening that Pandora's box
is by not getting mammograms, instead she decided to try improving
her diet and lifestyle to prevent getting breast cancer in the first place.