Q&A Topic: Systemic Therapies in the Treatment of Breast Cancer

Anthony C. Cahan, MD FACS

Q. A collaborative, multi-disciplinary approach to care is important in the treatment of breast cancer.  What is the role of a medical oncologist?

A. A medical oncologist assesses the need for and administers chemotherapy and/or endocrine therapy for women with breast cancer. Prior to, or following breast surgery, systemic therapies like chemotherapy and/or endocrine therapy may be used to treat tumors that are large, or to treat cancer cells that have escaped the confinement of the breast. To determine whether systemic therapies are necessary, your medical oncologist will look at the size of the tumor, the type of cancer, the presence or absence of cancer cells in your lymph nodes, and your age. Some women receive an OncoType Dx test, which genetically analyzes the breast tumor and helps predict the likelihood of the cancer recurring. This technology allows your medical oncologist to determine if a systemic therapy will likely be effective.

Q.  Why would a medical oncologist recommend chemotherapy before surgery?

A. Traditionally, chemotherapy has been used after surgery. However, for certain women, it makes more sense to reverse the traditional order of treatment. For women with larger tumors, chemotherapy may shrink the tumor – making a surgical removal successful, or even possible. In fact, chemotherapy treatment regimens in women with certain types of aggressive cancers have resulted in more than a 60 percent disappearance of the cancer by the time of surgery. This therapy may also result in the best cosmetic outcome for women – a smaller tumor may result in a breast conserving surgery, rather than a mastectomy at the time of surgery.

Q.  Why is chemotherapy used after surgery?

A. The goal of chemotherapy after surgery is to reduce the risk of breast cancer recurring by killing any cancer cells that may be left within the body. The widespread use of chemotherapy after surgery has resulted in increased survival and cure rates over the past 50 years for women with breast cancer.

Q. When is endocrine therapy necessary in the treatment of breast cancer?

Nearly two thirds—60 to 65 percent—of breast cancers are estrogen receptor positive, meaning these breast cancers might be promoted to grow due to the presence of estrogen. Endocrine therapy drugs such as tamoxifen, anastrozole, and others used in the treatment of estrogen receptor positive breast cancers provide further protection against the recurrence of cancer. These drugs are administered as oral medications that women may take at home. Endocrine therapy is usually employed after standard chemotherapy and radiation therapy for periods of five to 10 years.

Q. If a woman is pregnant, how do her treatment options change?

A. Breast cancer is found in about 1 in every 3,000 pregnant women. Depending on the stage of pregnancy and type of cancer, chemotherapy may be a treatment option. However, endocrine therapy is generally not recommended during pregnancy as it may affect the baby. Although a rare circumstance, it’s important to know that breast cancer during pregnancy can happen, and that any breast abnormality that arises should be evaluated. Women should also know that there are treatment options that will ensure the best possible outcome for both mom and baby. 


Anthony C. Cahan, MD FACS, has been Chief of Breast Surgical Services for The Breast Institute at Northern Westchester Hospital since 2002. His previous experience includes an internship and residency in general surgery at The New York Hospital-Cornell University Medical College, and cancer studies at Memorial Sloan-Kettering Cancer Center and Beth Israel Hospital.

Learn More About Dr. Cahan
Chief, Breast Surgical Services
The Breast Institute 
Northern Westchester Hospital

Northern Westchester Hospital is a proud member of Northwell Health.


Read Past Topics from Dr. Cahan: 
Lumpectomy v. Mastectomy

Stage 0 Breast Cancer
Managing Menopause After Breast Cancer

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