Chemotherapy and Breast Cancer Treatment

Current Treatment Landscape

Chemotherapy remains the primary treatment for roughly 50% of women diagnosed with breast cancer in the United States. However, recent research indicates that approximately 70% of these patients may be able to forgo chemotherapy and its adverse side effects.

Understanding the 21-Gene Test

Women diagnosed with hormone receptor-positive breast cancer, which has not yet metastasized to the lymph nodes, typically undergo a 21-gene test, such as Oncotype DX. This test utilizes a 100-point scale to assess the likelihood of cancer recurrence and to determine the appropriateness of chemotherapy as a treatment option.

– **High Scores**: A score of 26 or higher suggests a significant risk of recurrence, indicating that chemotherapy is the recommended treatment.
– **Low Scores**: A score of 10 or below implies a minimal risk of recurrence, leading to the conclusion that chemotherapy may not be beneficial.
– **Midrange Scores**: For scores between 11 and 25, the optimal treatment approach remains ambiguous.

Evaluating Treatment Options for Midrange Scores

Research Overview

A research team in the United States sought to determine whether endocrine therapy or chemotherapy would be more effective for women with early-stage breast cancer and midrange scores on the 21-gene test. Their findings, published in the *New England Journal of Medicine*, involved a nine-year follow-up of 9,719 breast cancer patients aged 18 to 75. All participants had hormone-receptor-positive, HER2-negative, axillary node-negative breast cancer, qualifying them for the 21-gene test.

Study Findings

Out of the total participants, 6,711 (69%) received midrange scores on the 21-gene test. The remaining patients comprised 1,619 (17%) with low scores and 1,389 (14%) with high scores. The researchers randomly assigned the 6,711 women with midrange scores into two treatment groups: one receiving endocrine therapy alone and the other receiving a combination of chemotherapy and endocrine therapy, referred to as chemoendocrine therapy.

Effectiveness of Endocrine Therapy

The results showed that endocrine therapy alone was as effective as the combined chemoendocrine therapy for women with midrange scores. After nine years, the overall survival rates were nearly identical: 93.9% for the endocrine-only group compared to 93.8% for the chemoendocrine group. Additionally, both treatment modalities demonstrated similar success in preventing distant cancer recurrence, with rates of 94.5% and 95%, respectively.

Impact of Age on Recurrence Risk

Despite the overall effectiveness of both treatments, the study revealed that the risk of cancer recurrence at distant sites was influenced by age. Specifically, women aged 50 years or younger exhibited lower recurrence rates following chemotherapy.

Conclusion: Rethinking Chemotherapy Necessity

This investigation aimed to identify the most suitable treatment options for women with early hormone-receptor-positive, HER2-negative, axillary node-negative breast cancer. The findings suggest that the necessity of chemotherapy is contingent upon results from a genomic test. Importantly, the researchers assert that up to 70% of women, particularly those with low to midrange scores on the 21-gene test, may avoid the harsh impacts of chemotherapy.

Source

Sparano JA, et al. Adjuvant chemotherapy guided by a 21-gene expression assay in breast cancer. NEJM. 2018. Available at: DOI: 10.1056/NEJMoa1804710.