Multiplex KRAS digital PCR assays have been described using the RainDropTM Digital PCR system (RainDance Technologies, Billerica, Massachusetts, USA) in advanced colorectal cancer [11] but not as yet with the Bio-Rad QX100 system, an affordable digital PCR system with commercially-available probes for several KRAS mutations, nor has a multiplex tool been used in lung cancer. Here, KRAS is linked to colorectal cancer.