Additionally, anti-HERV-K Env and Gag antibodies were observed to be elevated in patients with breast cancer (Wang-Johanning et al., 2008; Wang-Johanning et al., 2014), prostate cancer (Reis et al., 2013; Manca et al., 2022), pancreatic cancer (Li et al., 2017), ovarian cancer (Wang-Johanning et al., 2007), with changes in the titer of anti-HERV-K antibodies being associated with the disease course. The gene discussed is ERVW-1; the disease is breast cancer.