KISS1 and neoplasm: Healthy mice had significantly higher melatonin level (16.09 ± 1.26 ng/L vs 9.59 ± 0.98 ng/L, P = 0.002, t = 3.440) and significantly lower Kiss1 expression than tumor-bearing mice (3.08 ± 1.15 vs 11.96 ± 3.07, P = 0.003, t = 3.280).