Written by Ann Pietrangelo | Published on September 8, 2016
Researchers are getting closer to identifying women who can safely skip
chemotherapy as a treatment for breast cancer.
Some women with early stage breast cancer are at such low risk for recurrence
that chemotherapy is unnecessary.
For others, chemotherapy is a lifesaving treatment.
For the most part, doctors can’t predict which patients are which.
But we may be on the verge of a major change.
Early stage breast cancer usually means stage 1 and stage 2. In these stages
cancers haven’t spread beyond the breast or nearby lymph nodes.
Treatment usually starts with surgery and may be followed by hormone therapy
For many women with early stage breast cancer, treatment will also include
chemotherapy. The powerful drugs used are designed to kill fast-growing
cells throughout the body. That takes care of cancer cells, but also destroys
some healthy cells.
That’s why chemotherapy drugs cause hair loss and susceptibility
to opportunistic infections.
Side effects can also include fatigue, nausea, and weight loss. In the
long term, chemotherapy can impact fertility, harm organs, and increase
the risk of developing other cancers.
Thousands of breast cancer patients could avoid all that if they knew their
risk of recurrence.
That’s where genomic testing comes in.
Genomic study offers promise
A randomized study of 6,693 breast cancer patients from nine European countries
shows the promise of genomic testing.
Details of the study were published in
The New England Journal of Medicine.
All the women in the study had early stage breast cancer. To determine
their genomic risk of recurrence, researchers used the 70-gene signature
test called MammaPrint.
Clinical risk was also considered, which involves factors such as tumor
size, grade, and lymph node involvement.
Of the group, 1,550 patients were found to be at high clinical risk but
low genomic risk. Some had chemotherapy and some did not.
Among those who did not have chemotherapy, the five-year survival rate
without distant metastasis was 94 percent. For those who did have chemotherapy,
the rate was 1.5 percent higher.
Study authors concluded that about 46 percent of women with breast cancer
who are at high clinical risk of recurrence may not need chemotherapy.
editorial that accompanied the study said genomic testing can identify situations
where a specific intervention is not effective.
The editorial, written by Dr. Clifford A. Hudis and Dr. Maura Dickler,
went on to say, “A difference of 1.5 percentage points, if real,
might mean more to one patient than to another. Thus, the stated difference
does not precisely exclude a benefit that clinicians and patients might
Moving genomic testing into practice
“This study is a big deal,” said Dr. Timothy Byun, a medical
oncologist with The Center for Cancer Prevention and Treatment at St.
Joseph Hospital in Southern California, who was not involved in the study.
In an interview with Healthline, Byun said the study may result in fewer
breast cancer patients getting chemotherapy, at least in European countries.
“In the United States, many of us have already been using the Oncotype
DX test to help guide our decisions,” said Byun. “It uses
a 21-gene score. It gives similar information, but we don’t know
if there’s a 100 percent correlation with the MammaPrint test.”
Byun referred to the recent
TAILORx Trial using the 21-gene test. It found that low-risk patients did well without
That study showed the test could select a cohort of patients with a 99
percent chance of five-year survival without distant metastasis. For those
women, the risks of chemotherapy aren’t justifiable.
Researchers are still waiting for this data to mature, cautions Byun.
“We know that when oncologists see patients after surgery, we look
at traditional clinical indicators to guide our decision-making process
as to benefits and harms of chemotherapy,” he said.
"It would be nice if we could have this kind of tool to guide clinicians
to fine tune who does and doesn’t need therapy for lung, colon,
and other cancers."
- Dr. Timothy Byun, The Center for Cancer Prevention and Treatment
With the information currently available, it’s likely that some breast
cancer patients get unnecessary chemotherapy.
“The crux of the European study is they wanted to see if genomic
study could give a more precise answer as to who really needs treatment
and who doesn’t,” said Byun. “Those who don’t
could avoid chemotherapy, which is toxic to many patients.”
There’s a caveat, according to Byun. Genomic studies, for the most
part, have included only estrogen-receptor positive breast cancer patients.
“The European study did include some patients who were estrogen-receptor
negative, HER2-positive, and triple-negative. But since the number was
relatively small, it’s not clear if we should be using this information
for all patients,” he said.
Referring to the 1.5 percent difference in metastasis-free survival in
favor of chemotherapy, Byun said, “It’s a small difference,
but it makes us wonder if there’s some benefit to chemotherapy in
“When we look at the survival curve, decade after decade, more women
than ever are surviving breast cancer because of adjuvant chemotherapy,”
he added. “Yes, there’s an overtreatment, but the population
as a whole is benefiting from it. “
Byun said overtreatment is not unique to breast cancer.
“We have the same problem with lung and colon cancers. It would be
nice if we could have this kind of tool to guide clinicians to fine tune
who does and doesn’t need therapy for lung, colon, and other cancers.
There is an Oncotype DX for colon cancer, but it doesn’t have that
type of predictive power.”
Into the future
Byun said genomic testing is still far off from becoming mainstream.
“The field is moving toward more precision medicine and moving away
from traditional chemotherapy. Having said that, chemotherapy is still
going to play a role, but it will become more selective. More will be
spared from unnecessary chemotherapy. More people who need it will get
it,” he said.
“Instead of treating 100 people to benefit two or three, we could
do a much better job of figuring out who would benefit,” Byun explained.
“This study was a major effort by our European colleagues and they
ought to be applauded. The study does show that the use of genomic information
can help some patients avoid chemotherapy. That’s all positive information,” he said.