An analysis of 546 patients with breast cancer who received neoadjuvant chemotherapy demonstrated that residual cancer burden is prognostic for overall survival, recurrence-free survival, and distant relapse–free survival, according to research presented by White et al at the Society of Surgical Oncology 2021 International Conference on Surgical Cancer Care (Poster 15).
Residual cancer burden after neoadjuvant chemotherapy has been associated with prognosis and disease-free survival. In some settings, additional systemic therapy is now recommended in patients with persistent disease. Optimizing the prognostic value of residual cancer burden may impact subsequent treatment recommendations.
Single-Institution Analysis
The research team analyzed 546 patients from a single institution between 2010 and 2016. A residual cancer burden index was calculated, and endpoints of relapse-free survival, distant relapse–free survival, and overall survival were analyzed. Patients were followed for an average of 61 months.
Distribution of phenotypic subtypes was:
- 37% hormone receptor–positive/HER2-negative
- 36% HER2-positive
- 27% triple-negative.
Residual cancer burden (RCB) distribution was RCB-0 in 23%, RCB-1 in 13%, RCB-2 in 41%, and RCB-3 in 23%. RCB-0 was achieved in 36% of those with triple-negative breast cancer, 30% of those with HER2-positive disease, and 8% with hormone receptor–positive/HER2-negative disease. RCB-3 was identified in 34% of patients with hormone receptor–positive/HER2-negative disease, 19% with triple-negative disease, and 14% with HER2-positive disease. Local recurrence was identified in 5%; distant recurrence was identified in 17%. Death occurred in 16%.
Kaplan-Meier 5-year survival estimates were 84%, 76%, and 80% for overall survival, recurrence-free survival, and distant relapse–free survival, respectively. The residual cancer burden index showed good prognostic ability for overall survival, recurrence-free survival, and distant relapse–free survival, with Harrell’s c-indices of 0.68, 0.67, and 0.68, respectively.
Researchers reported that the RCB index discriminates well for each survival endpoint within HER2-positive and triple-negative breast cancer subtypes, but does not for hormone receptor–positive/HER2-negative (overall survival C-indices = 0.74, 0.77, and 0.53, respectively). When controlling for additional variables, including phenotypic subtype and clinical stage, the models have higher prognostic ability for overall survival, recurrence-free survival, and distant relapse–free survival (Harrell’s c-indices = 0.75, 0.72, and 0.73, respectively).
“We demonstrated that a multivariable model including RCB index, phenotypic subtype, and clinical stage improved the discriminative ability for overall survival, recurrence-free survival, and distant relapse–free survival compared to univariate models of RCB,” concluded the authors.
