Incidence of second primary prostate cancer was also higher in men diagnosed with AJCC stage I (SIR = 1.36, 95% CI 1.04–1.75) and hormone receptor-positive breast cancer (SIR = 1.23, 95% CI 1.11–1.39) with an excess of 24 and 22 cases per 10,000 person-years respectively. Here, NR4A1 is linked to prostate cancer.