From the Guidelines
The most effective approach to monitor treatment of triple negative breast cancer (TNBC) is a combination of regular clinical examinations, imaging studies, and blood tests for tumor markers, with no single best test available. This approach is necessary due to the aggressive nature of TNBC and its higher risk of early recurrence, especially in the first 3-5 years after diagnosis 1. For patients undergoing neoadjuvant chemotherapy, response is typically assessed through clinical examination and imaging every few cycles. After surgery, surveillance generally includes clinical examinations every 3-6 months for the first 3 years, then every 6-12 months for years 4-5, along with annual mammography.
Some key points to consider in monitoring TNBC treatment include:
- The use of PD-L1 testing, such as the 22C3 assay, to determine suitability for treatment with pembrolizumab plus chemotherapy, with a positive result defined as a CPS of at least 10 1.
- The potential role of circulating tumor DNA (ctDNA) assays in monitoring treatment response, although standardization and clinical validation are still needed 1.
- The importance of testing for PIK3CA mutations in patients with metastatic luminal breast cancer, as this can inform treatment with alpelisib 1.
- The use of immune checkpoint inhibitors, such as atezolizumab, in combination with chemotherapy for first-line treatment of triple-negative ABC, with PD-L1 status tested using the Ventana PD-L1 (SP142) assay 1.
In terms of specific treatments, sacituzumab govitecan has been shown to improve progression-free survival (PFS) and overall survival (OS) compared to standard therapy in patients with metastatic TNBC who have received at least two prior therapies 1. However, the choice of treatment and monitoring approach should be individualized based on patient characteristics, tumor biology, and treatment history. Ultimately, a comprehensive monitoring approach that incorporates multiple modalities is necessary to optimize outcomes in patients with TNBC.
From the Research
Monitoring Treatment of Triple Negative Breast Cancer
To monitor the treatment of triple negative breast cancer, several tests can be utilized, including:
- Circulating tumor DNA (ctDNA) tests, which can predict response to neoadjuvant chemotherapy and long-term outcomes 2, 3, 4
- FDG PET/CT scans, which may predict response to neoadjuvant chemotherapy in ER-positive/HER2-negative and triple negative breast cancer, but not in HER2-positive breast cancer 5
- Circulating tumor cell (CTC) enumeration, although its association with treatment response is less clear 2
Predictive Value of ctDNA
ctDNA has been shown to be a predictive and prognostic marker in triple negative breast cancer, with early clearance of ctDNA associated with improved outcomes 2, 3. Custom micro-panels of 4-6 variants can be used to track disease and predict clinical outcomes for patients with TNBC 3.
Comparison of Tests
While FDG PET/CT scans may be useful in predicting response to neoadjuvant chemotherapy, ctDNA tests have been shown to be more sensitive in detecting molecular relapse in advance of clinical relapse 5, 3. CTC enumeration has been less consistently associated with treatment response 2.
Clinical Implications
The use of ctDNA tests, such as custom micro-panels, may improve patient outcomes through early detection of relapse and preemptive intervention prior to symptom onset 3. Platinum-based chemotherapy has been shown to improve disease-free survival and overall survival in early triple negative breast cancer, although it is associated with increased hematological toxicity 6.