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Guide 02- Surgeons: Susan
Love, MD
Edited comments by Dr Love
Anatomy of the breast ductal system
It’s amazing but we really don’t know the anatomy
of the breast ducts. Classically, all the textbooks say there are
15 to 20 ducts in each breast, but that information dates back to
Sir Ashley Cooper in 1839. He found there were 15 to 20 straight
tubes coming out of the nipple, but he was only able to cannulate
five to eight different ducts. Since then others have come up with
similar findings. In the 1970s, Otto Sartorius, a surgeon in Santa
Barbara, found five to eight ducts. Dr. Teboul, an ultrasonographer
in Paris, found that although there were 15 to 20 different ductal
systems, there were actually only five to eight holes in the nipple,
suggesting some of the ductal systems come together behind the nipple.
I conducted research mapping breast ducts in lactating women and
also found six to eight ducts that formed a pattern. There are two
or three in the center of the nipple and the others are arranged
more peripherally — almost like two concentric circles. We
then re-analyzed over 600 of Dr. Sartorius’ ductograms and
confirmed an inner group of ducts that go straight back from the
nipple, and a more peripheral group that extend more radially.
The notion we’ve had that the ductal system is like the
spokes of a wheel and that removing a wedge of breast tissue removes
an entire ductal system may not always be right. The ductal system
is not flat, it’s three-dimensional. To remove a central duct,
you may want to core directly back. To excise an entire ductal system,
a ductogram before surgery would be beneficial in locating the duct
rather than just cutting blindly around calcifications and getting
positive margins.
Ductal lavage for patients at high risk for breast
cancer
The real role of ductal lavage right now is the assessment of
women at high risk for breast cancer. We lavage the fluid-producing
ducts because studies looking at nipple aspirate fluid showed these
ducts were at higher risk for disease than the nonfluid-producing
ducts.
The information gained from ductal lavage assists physicians and
high-risk patients in management decisions, such as chemoprevention
or prophylactic mastectomy. For example, if you have a patient in
her twenties who is considering tamoxifen because her mother died
of premenopausal breast cancer, we know that five years of tamoxifen
reduces her risk, but during which five years should she take it?
One could monitor her with ductal lavage. As opposed to mammography,
which is less useful in young women, ductal lavage works great in
young women.
A patient with a breast cancer gene has a 50 percent to 80 percent
risk of breast cancer, but that’s a pretty wide range. If
she’s considering prophylactic mastectomy, knowing whether
she has atypia would be invaluable. The same holds true for women
with breast cancer in one breast who are considering a prophylactic
mastectomy in the contralateral breast.
In the future ductal lavage may prove useful for menopausal women
at high risk for breast cancer who are considering hormone replacement
therapy. Instead of waiting to see if they develop cancer, one could
perform ductal lavage every six months or annually to see what the
cells are doing. It’s premature to use it in the general population,
because we don’t know what to do with the information in women
who are not at high risk. For now, it has an important role in risk
assessment as we continue to research its potential in other areas.
Aromatase inhibitors for prevention in postmenopausal
women
There is some data that shows that estrogen levels are 40 times
higher in the breast duct fluid than they are in the blood in postmenopausal
women. And the breast itself has aromatase. It may be making its
own estrogen. If this is the case in postmenopausal women, that
may be why anastrozole may actually be a better drug than tamoxifen
for prevention in that group. It probably is not going to have as
much of an impact in premenopausal women.
I’m very interested in conducting research to look at whether
you can change the hormone levels in the breast duct fluid and whether
we can monitor that. If so, that may be another way to determine
which patients need prevention. If the hormone levels are very high,
then we could put the patient on tamoxifen or aromatase inhibitors.
The mammography debate
One problem is people say things such as, “Mammography can
find 80 percent of breast cancers.” Absolutely true —
but that’s not saying it finds 80 percent at an early stage.
Then we say, “Mammography can find breast cancer early.”
Absolutely true — it can, but it doesn’t always. And
then we say, “Early breast cancer is 95 percent curable.”
Absolutely true — but people conclude from these statements
that mammography can find 80 percent of breast cancers when they’re
95 percent curable, and that is not true at all.
In my mind, the data in women over 50 still looks reasonable,
and I think annual mammography is worthwhile in this age group.
Under 50, I think its benefit is limited because the breasts are
denser and the cancers grow faster. These women need to discuss
screening with their physicians. And physicians need to tell women
that this is the best data we have, and we’re never going
to have more accurate data because we’re never going to do
another big randomized study. Mammography is the best screening
tool we have at the moment, but it’s far from perfect. It
would be great if we had something better and, in a way, that’s
what has driven me to look at the intraductal approach. I’d
like to get closer to the Pap smear model where we find atypia,
not cancer, and then stop the process so that the patient never
develops cancer.
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