Prior cancers reported by pathogenic MMR gene variant carriers included breast cancer with tamoxifen use (9.1% vs 6.1% in the reference group, P = 0.6), prior LS‐associated cancer (18% vs 2%, P < 0.0001), and other prior cancer (18.2% vs 4.7%, P = 0.005). This evidence concerns the gene MRC1 and breast carcinoma.