Combined use of immunoreactivities of Efp and ZCCHC3 for predicting prognosis of patients with triple‐negative breast cancer

We previously reported that strong immunoreactivity (IR) of estrogen-responsive finger protein (Efp), also known as tripartite motif-containing 25 (TRIM25), predicts poor prognosis in patients with estrogen receptor-positive and -negative invasive breast cancers. In the present study, we investigated the clinicopathological role of Efp and ZCCHC3, the latter of which is an Efp interactor, in a triple-negative breast cancer (TNBC) cohort which was composed of 118 Japanese female breast cancer patients underwent surgical treatment. Efp and ZCCHC3 IRs were analyzed using specific antibodies for these proteins. We demonstrated that positive Efp IR was significantly associated with shorter distant disease-free survival (p = 0.0108) and that positive ZCCHC3 IR was also significantly associated with shorter distant disease-free survival (p = 0.0153). Notably, ZCCHC3 IR was positively associated with Efp IR (p = 0.003). When IRs of the two proteins were combined, double positivity was associated with shorter distant disease-free survival (p = 0.0007) and was an independent factor for poor prognosis. These results suggest that IR positivity of Efp and ZCCHC3 has clinical significance as a poor prognostic factor in patients with TNBC. Thus, we propose that the combined use of both IRs can be used as a prognostic marker for TNBC.