In a study examining the correlation between lymph node metastasis and clinicopathological features among 91,364 patients with T1 breast cancer using information from the “Surveillance, Epidemiology, and End Results Program (SEER)” study, age, race, primary site, tumor size, and ER, PgR, and HER2 status were influencing factors [38]. This evidence concerns the gene PGR and breast cancer.