Is Chemotherapy Really Necessary for Early-Stage Breast Cancer?

No one wants to experience breast cancer, but knowing the best treatment path can make a significant difference when faced with this challenge. The American Society of Clinical Oncology (ASCO) recently updated guidelines to help doctors and patients choose the most effective treatments based on the specific characteristics of the cancer. Let's break down these guidelines into simpler terms.

Who Do These Guidelines Apply To?

These guidelines are designed for women diagnosed with early-stage invasive breast cancer. Early-stage means the cancer has not spread far within the body. These recommendations help doctors and patients decide on additional (adjuvant) treatments after surgery, like hormone therapy or chemotherapy.

What Are Biomarkers?

Think of biomarkers as clues found in the cancer cells that can tell us how aggressive the cancer is and how it might respond to treatments. The ASCO guidelines focus on which biomarkers to check for making treatment decisions.

The Tests and What They Tell Us

• Oncotype DX (21-gene recurrence score): This test is especially for those with ER-positive, HER2-negative breast cancer. It helps decide if adding chemotherapy to hormone therapy is beneficial. For certain scores, the test suggests chemotherapy can help alongside hormone therapy, especially in younger patients or those with cancer spread to a few lymph nodes.
• MammaPrint (70-gene signature): This test is used for patients above 50 with high-risk cancer, whether it has spread to lymph nodes or not. However, it's not recommended for younger patients with high-risk, node-positive cancer.
• EndoPredict (12-gene risk score) and Prosigna (PAM50): These tests are for postmenopausal women with node-negative or limited node-positive cancer to guide treatment decisions. They're not as broadly recommended for premenopausal women or those with cancer spread to many lymph nodes.
• Ki67: This measures how fast cancer cells are growing. It's useful in specific situations to help guide treatment when other gene tests aren't available.
• Immunohistochemistry 4 (IHC4): This test can be used if other gene tests aren't available, based on its validation in specific labs.

Extended Therapy Decisions

After 5 years of hormone therapy, the decision to continue treatment depends on the risk of cancer returning. Tests like the Breast Cancer Index (BCI) and clinical treatment score after 5 years (CTS5) can help estimate this risk and guide decisions on continuing hormone therapy.

HER2-Positive or Triple-Negative Breast Cancer

For those with HER2-positive or triple-negative breast cancer, the current multiparameter gene expression or protein assays (like Oncotype DX, MammaPrint, etc.) are not recommended for guiding treatment decisions.

Emerging Biomarkers

New areas of research like tumor-infiltrating lymphocytes (TILs), PD-L1 testing, circulating tumor cells (CTC), and circulating tumor DNA (ctDNA) show promise, but they're not yet recommended for guiding treatment decisions in early-stage breast cancer.

The Bottom Line

Understanding the specific characteristics of breast cancer can help tailor treatment to each individual, potentially improving outcomes and minimizing unnecessary side effects. These guidelines are a step towards more personalized cancer care, offering hope for more effective and targeted treatments. Be sure to ask your oncologist if you qualify for any of these testing options.