H2AX and cancer: Patients with previous cancer irradiation (therapy) or sleep apnea had an increased number of H2AX foci/cell (6.00±0.42 and 5.92±1.64, respectively) compared with those not known to have these conditions (4.11±0.27 and 4.15±0.32, respectively) but did not reach statistical significance (p = 0.23 and p = 0.097, respectively).