Treatment sequencing for breast cancer is a complex process designed to optimize patient outcomes. The order in which different therapies are administered can make a major difference in treatment efficacy, quality of life and survival.
While treatment sequencing will vary from patient to patient based on a variety of individual factors, there are some general guidelines that most physicians follow when deciding on a treatment regimen.
Stages 0, I and some stage II breast cancers
The stage of your cancer at diagnosis may dictate the order of treatments. For stage 0, I, IIA and some IIB breast cancers, treatment usually begins with surgery. The goal of the procedure is to remove as much of the cancer as possible before moving on to drug-based therapy. In some cases, breast-conserving surgery, or lumpectomy, is possible, while in others, a mastectomy might be required. Surgery may also involve removal of surrounding lymph nodes.
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The next step after surgery is often radiation, which helps to kill off remaining cancer cells. Radiation is more common in patients who received breast-conserving surgery than in those who received mastectomy. If cancer cells were found in the lymph nodes, you may need radiation even if you received a mastectomy.
Some, but not all, individuals with stage I and II breast cancer receive systemic therapy, which includes chemotherapy, immunotherapy and targeted therapies. Systemic therapy generally isn’t used for stage 0 breast cancer, though hormone receptor-positive cases may receive hormone therapy.
The exact treatment plan depends on several factors, including:
- Hormone receptor status: Individuals with hormone receptor-positive cancer may receive hormone therapy after surgery, such as tamoxifen or aromatase inhibitors.
- Tumor size: If the original tumor was large or rapidly growing, chemotherapy may be administered after surgery.
- Human epidermal growth factor receptor 2 (HER2) status: Patients with HER2-positive breast cancer may receive chemotherapy and trastuzumab both before and after surgery. Some may also receive pertuzumab.
- Having triple-negative breast cancer: Pembrolizumab, a type of immunotherapy, is often given to people with triple-negative breast cancer before or after surgery. These patients may also need chemotherapy.
- BRCA mutation status: Those who test positive for BRCA mutations and have hormone receptor-positive, HER2-negative cancer might receive olaparib, a targeted drug, after surgery.
Stages IIB and III breast cancer
Oftentimes, treatment of stages IIB and III breast cancer begins with systemic therapy, known as neoadjuvant therapy. The purpose of this method is to help shrink large tumors before proceeding with surgery, increasing the chances of successful surgery and improved survival.
Sometimes, patients with later stage II or stage III breast cancer might receive surgery first in the form of mastectomy, which is followed by systemic therapies. In either case, many patients will undergo radiation after surgery.
Metastatic breast cancer
The main goal of treatment for metastatic breast cancer is to slow the spread of cancer throughout the body. As such, treatment generally begins with systemic therapy.
Patients with hormone receptor-positive metastatic breast cancer often receive hormone therapies, which can also be combined with CDK4/6 inhibitors. Individuals with hormone receptor-negative cancer may receive chemotherapy.
For people with HER2-positive metastatic cancer, treatment may begin with chemotherapy in combination with HER2-targeting drugs like trastuzumab or pertuzumab.
Immunotherapy and chemotherapy may be prescribed for metastatic triple-negative breast cancer.
Occasionally, surgery and radiation may be recommended to patients with metastatic breast cancer to help alleviate symptoms or address complications.
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