Fig 1. Experimental workflow.

DNA extracted from three patient groups was sequenced after treatment with and without UNG. The fixation group consisted of three patients from 2015 where paired tissue samples were snap frozen or put into formalin for a determined length of times. A baseline group consisting of 20 patients all from 2015/16 were fixed in formalin for an unknown amount of time. The block age group consisted of three patients from 1994, three from 2004 and three from 2014; all samples had an unknown fixation time. DNA was extracted from normal (N) and tumor (T) tissue when available.