To determine if FST and FSTL3 serum levels correlate with tumor growth and can serve as biomarkers of tumor burden, we monitored their levels in a syngeneic mouse model of CCNE1-amplified high-grade serous carcinoma (KPCA.C cell line clone), which we have previously reported secretes FST (~50pg/ml in KPCA supernatant) [25]. Here, FSTL3 is linked to neoplasm.