Why Experts Are Rethinking Chemotherapy for Breast Cancer

Large study finds genetic test accurate for breast cancer
Portrait of young woman suffering from cancer

Contributor: Jame Abraham, MD 

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Some women with certain breast cancers may safely avoid chemotherapy after surgery, according to results of a recent study. The research, which is part of a growing body of evidence, shows that a genetic test can determine your risk of not including chemotherapy in cancer treatment.

Chemotherapy is very effective in treating breast cancer. But it is not without side effects. And, in some cases, it is unnecessary, researchers say.

The test, which ranks patients according to risk, has been used for years, but was recently validated in a study of more than 10,000 women.

The study affirmed that a common genetic test can accurately tell women with certain breast cancers whether they can instead be treated with endocrine therapy, which is less harsh than chemotherapy.

More than a decade ago, the National Institutes of Health advised most women with breast cancer to undergo chemotherapy after surgical treatment.

Now doctors are re-thinking that, in particular for women with low-risk disease who likely will do just as well with following surgery with endocrine therapy (more below).

How chemotherapy takes its toll

Doctors use chemotherapy to destroy cancer cells. A cytotoxic drug used in chemotherapy gets in the way of cancer cells dividing and growing. It doesn’t necessarily destroy the cells; it may just interrupt their growth.

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If possible, doctors design treatment to spare normal cells. But chemotherapy often takes a toll on patients. It can cause heart and nerve damage, osteoporosis and infertility.

Chemotherapy also makes tumor cells more sensitive to the effects of radiation. This lets doctors use smaller doses of radiation to control cancer.

What is adjuvant endocrine therapy?

If you have breast cancer, your oncologist may talk about adjuvant endocrine therapy.

In chemotherapy, “adjuvant” means using anticancer drugs with, or after, another treatment. For example, they may use therapy after surgery to remove a tumor.

Doctors may perform surgery and then use chemotherapy to kill any undetected cancer cells. That’s adjuvant chemotherapy.

Adjuvant endocrine therapy is very common in treating breast cancer, and what makes it especially attractive is that it has fewer side effects and aftereffects than chemotherapy.

Doctors use adjuvant endocrine therapy for patients who have a low risk of cancer recurrence.

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Treating cancer with fewer side effects

Your doctor will work with the hospital’s laboratory to decide how likely it is that your cancer will recur.

He or she will learn from the lab about certain proteins in your cells — estrogen and progesterone receptors — that tell whether you would do well with adjuvant endocrine therapy.

The therapy has side effects, but they are less damaging than those of chemotherapy.

The test which can give you the definitive answer is Oncotype DX. It looks at 21 of your genes and, based on what it finds, helps your oncologist decide which therapy is best for you.

The test isn’t for everyone; it’s for patients with hormone-receptor-positive, HER2-negative breast cancer who have a low risk of recurrence. Your oncologist will help you decide if this is right choice for you.

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