We analyzed circulating cell-free DNA (cfDNA) extracted from plasma using high-depth massively parallel sequencing targeting 468 cancer-associated genes, and we identified a clonal hotspot missense mutation in the <i>PIK3CA</i> gene (3:178952085, A > G, H1047R) and amplification of the <i>CCND1</i> gene. Here, PIK3CA is linked to cancer.