RCN3 (r =  − 0.319, p < 0.05) and CALU (r = – 0.215, p < 0.05) expressions had significantly negative correlations with tumor purity, while a weak negative correlation was observed between SDF4 expression and tumor purity (r =  − 0.125, p < 0.05). The gene discussed is RCN3; the disease is neoplasm.