EXO1 and cancer: Exo1 K589E polymorphism was significantly associated with an increased cancer risk in smokers (Lys/Lys+Glu/Lys vs Glu/Glu: OR = 2.16, 95%CI:1.77–2.63, P<0.01), but no association was observed in non-smokers (Lys/Lys+Glu/Lys vs Glu/Glu: OR = 0.89, 95%CI:0.64–1.24, P = 0.50).