This increase is largely owing to a 3.8-fold elevation in SBS13 mutations (P < 0.0001 by Mann–Whitney U test), whereas SBS2 mutations occurred at similar levels between BRCA1/2-proficient and BRCA1/2-deficient tumors (median values of 151 and 142 SBS2 mutations per tumor), respectively. Here, BRCA1 is linked to neoplasm.