INS and neoplasm: Tumour growth markedly decreased the plasma insulin concentration in the group W compared to groups C and P (C = 6.013 ± 1.000 ng.mL-1; W = 0.785 ± 0.077 ng.mL-1*; P = 3.500 ± 0.408 ng.mL-1;*p < 0.05 compared to C and P).This finding agreed with other studies in Walker tumour-bearing rats that reported a reduction in the plasma insulin level caused by a decrease in insulin synthesis and release by the β-cells of pancreatic islets [26,27].