However, there is no significant difference in circulating IL-37 mRNA expression among breast cancer patients with metastasis among the ER+/PR+/HER2+, ER+/PR+, and PR+ breast cancer patients (57), suggesting that IL-37 expression may be stage dependent, i.e. is more protective among the breast cancer patients without metastasis, but less effective on the patients with metastasis. Here, PGR is linked to breast carcinoma.