Cell‐free DNAs (cfDNAs) are DNA fragments that are released from tumor cells or systemic cells and have been used as a less‐invasive biomarker in several cancers.24 Studies have suggested that genetic mutations and copy number changes in cfDNAs could be used to monitor treatment responses or evolution of tumors.25 To determine whether PINK1 can be released and detected as cfDNA, we measured cfPINK1 DNA in the culture medium of MM cells treated with CCCP or salinomycin. This evidence concerns the gene PINK1 and cancer.