Analyzing cancer tissues with this epigenetic clock, composed of methylation levels from 353 CpGs, indicated that tissues from cancer patients treated with various therapies appeared to be an average of 36 years older compared to the actual chronological age of the patients, while induced pluripotent stem cells (iPSCs) from the same individuals showed resetting of the clock to an epigenetic age of zero. The gene discussed is CLOCK; the disease is cancer.