- Low-volume residual nodal disease (i.e., micrometastases or isolated tumor cells [ITCs]) after neoadjuvant chemotherapy (NAC) is associated with around 2 times worse DFS and OS.
Why this matters
- Findings warrant performance of immunohistochemistry on sentinel nodes after NAC.
- Nodal micrometastases or ITCs after NAC may warrant further local and systemic therapy.
- Analysis of 2 cohorts: cohort 1: 967 patients with cT1-4N0-1 breast cancer treated with NAC at the Dana-Farber/Brigham and Women's Cancer Center (DFBWCC); cohort 2: 35,536 patients in the National Cancer Database (NCDB).
- Funding: DFBWCC.
- DFBWCC cohort:
- Median follow-up, 5.3 years.
- Prevalence of ITCs, 2.8%.
- Prevalence of micrometastases, 6.3%.
- 5-year DFS (vs node-negative) is worse for patients with ITCs (aHR, 2.36; 95% CI, 1.01-5.51) and micrometastases (aHR, 2.14; 95% CI, 1.20-3.81).
- No difference in 5-year OS (vs node-negative) for both groups.
- NCDB cohort:
- Median follow-up, 3.7 years.
- Prevalence of ITCs, 1.5%.
- Prevalence of micrometastases, 3.2%.
- 5-year OS (vs node-negative) is worse for patients with ITCs (aHR, 1.89; 95% CI, 1.39-2.59) and with micrometastases (aHR, 2.18; 95% CI, 1.76-2.70).
- No data on DFS in the NCDB cohort.
- Small number of patients in the DFBWCC cohort with nodal micrometastases and ITCs precludes subgroup analysis.