By univariate analysis, advanced ovarian cancer [advanced versus early, HR: 3.6 (95% CI 2.2–5.8), p < 0.001], serous ovarian carcinoma [serous versus non-serous, HR: 1.5 (95% CI 1.1–2.2), p = 0.01], high-grade tumor [grade 3 versus grades 1–2, HR: 2.0 (95% CI 1.1–3.4), p = 0.015], ≥1 cm postoperative residual tumor [≥1 cm versus < 1 cm, HR: 2.8 (95% CI 2.1–3.9), p < 0.001], and detectable BTLA expression in cancerous tissue [detectable versus non-detectable, HR: 2.0 (95% CI 1.4–2.9), p < 0.001] were associated with significantly negative impacts on DFS. The gene discussed is BTLA; the disease is ovarian serous carcinoma.