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For the past 40 years, the standard recommendation for
treating breast cancer has included surgery and radiation, sometimes followed
by chemotherapy. Chemotherapy is effective but arduous, killing cancer cells but
leaving people extremely fatigued and ill. Few treatments have the negative
connotations that chemo does, and now, fewer women may have to undergo it.
New research shows a test given to women with early stage
breast cancer can reliably assess their risk for developing further cancer,
helping doctors decide whether or not surgery and radiation are sufficient. The
test has been around for years, but its accuracy has been validated in the
study of 6,700 women. It showed that women whose test results indicate they
have a low risk of recurrence can skip chemotherapy without raising their
chances of having more cancer.
How the Test Predicts the Risk of Cancer
The test is called MammaPrint. It is widely available and
involves taking a small breast tissue sample, which is sent to a lab where
the activity level of 70 different genes associated with breast cancer is
analyzed. Every cancer is biologically unique, but the test assigns a score
that indicates whether the cancer has a low or high chance of recurring. Your
doctor can reliably use the results to decide what treatment to recommend to
you. If your score indicates you have a low genetic risk, your doctor may not
feel chemotherapy is necessary, because it will not affect your chance of recurrence
or developing another cancer.
Who Is Eligible for the Test
MammaPrint can be used to help doctors determine the need
for chemotherapy in women with cancer with the following traits:
-
It is a stage I or stage II (early stage cancer).
-
It may be invasive, meaning there is cancer in
the tissue surrounding a tumor. -
The tumor is smaller than 5 centimeters.
-
The cancer can be either estrogen-receptor
positive or negative.
How the Test Helps Doctors Recommend Treatment
Before the MammaPrint study, doctors would make treatment
decisions based on a cancer’s characteristics like tumor size, the presence of
certain hormone receptors (substances that lead to changes in cells), and
whether there were cancer cells in the lymph nodes, meaning it had spread
beyond the tumor. But knowing the genetic makeup of a particular cancer means
your doctor has a clearer picture of your individual situation. Using the new
test, 20% of the women who had cancers that were previously considered high
risk were re-classified as low risk, meaning they carried only a 10% chance of
coming back.
The test means more women can be treated with hormone
therapy, also known as endocrine therapy, instead of chemotherapy. Hormone
therapy is already a common treatment for breast cancers that are localized and
not advanced. It is less harsh than chemotherapy, though it does have side
effects including hot flashes, fatigue and vaginal dryness. Common medicines
used in hormone therapy are tamoxifen and anastrozole, which are pills you may take
for a number of years.
Talking to Your Doctor About the MammaPrint Test
Nearly half of all women with early stage breast cancer have
a low genetic risk of recurrence. That translates into a significant number of
people who can avoid having unnecessary chemotherapy. If you have had a
diagnosis of breast cancer, talk to your doctor about the MammaPrint test. Every
cancer and every patient is different, so your doctor will assess other factors
as well as test results to give you a treatment recommendation. Your age,
general health, and family history will also play a role in determining
treatment. But for thousands of women, the results of the MammaPrint study can
mean an easier journey along the road to overcoming cancer.