GSTM1 and cancer: Table 2 shows clinical characteristics including ganglion affectation and TNM staging. Regarding polymorphism detection in GSTM1 genotypes, patients presenting GSTM1 did not show deletion (null) polymorphism, whereby the gene maintains its detoxification function for potentially toxic compounds. This was observed in 73.91% of control subjects and in 50% of cancer patients (p = 0.042).