In contrast, estradiol (OR [95% CI] = 2.424 [1.113–5.278], P = 0.0257), parathyroid hormone-related protein (PTHrP) (OR [95% CI] = 2.887 [1.124–7.418], P = 0.0276), and insulin (OR [95% CI] = 1.237 [1.079–1.418], P = 0.0364) were found to be significantly associated with an increased risk of SCLC (Figure 9). Here, INS is linked to small cell lung carcinoma.