When exploring associations by tumor size, little evidence of heterogeneity was observed for IL-6 and breast cancer risk (Fig. 3, P-homogeneity = 0.90), although significant associations were observed only in tumors <  = 2 cm and 2–5 cm (< = 2 cm: ORper SD increment = 1.63 (1.09–2.44); 2-5 cm: ORper SD increment = 1.43 (1.01–2.02) but not for larger tumors (> 5 cm: ORper SD increment = 1.17 (0.85–1.61)). The gene discussed is IL6; the disease is breast cancer.