In another small study of residual tumors in 32 patients with HER2+ breast cancer, it was shown that after NAC, 69% of patients had an increased number of mutated genes (21 gene panels studied) compared to their biopsy; this was shown to be a negative prognostic factor in terms of disease-free survival, as the recurrence rate in the subgroup with a different gene profile was 42% versus 0% in the subgroup with the same profile (p = 0.019) [11]. Here, ERBB2 is linked to breast cancer.