Breast cancer (BC) is the most common tumor in women(Joe et al., 2022). Among them, triple-negative breast cancer (TNBC) is the most invasive subtype of BC, featured by the lack of estrogen and progesterone receptors, and the poor or lack of expression of human epidermal growth factor-2 (HER-2)(Sixto-Lopez, Ordaz-Pichardo, Gomez-Vidal, Rosales-Hernandez, & Correa-Basurto, 2023; Wu et al., 2023). Numerous studies have shown that TNBC is highly prone to recurrence and metastasis, so, its prognosis was worse than subtypes of BC, and the 5-year survival rate of TNBC patients with distant metastasis is only 11%(Kaur et al., 2023; Li et al., 2023; Lim et al., 2020). Presently, the American Joint Commission on Cancer (AJCC) staging guidelines have become the gold standard for evaluating tumor prognosis(Amin et al., 2017). However, it ignores other clinically relevant factors that affect cancer prognosis, and therefore has certain limitations at the level of individualized treatment. This study is important, and to our knowledge, it is the first to analyze the relevant risk factors affecting the survival and prognosis of TNBC patients with organ metastasis. We found that age (years) at diagnosis, race, marital status, histologic type, stage, T/N stage, histologic grading, the primary site, surgery of primary site, radiotherapy, and chemotherapy are independent risk factors affecting the prognosis of TNBC patients. Furthermore, age, T stage, surgery of primary site, and chemotherapy are independent predictors in TNBC patients with organ metastasis. In addition, numerous studies show that the risk of TNBC metastasis in the first 1–3 years is relatively high(Flores Fortis, Perez Anorve, Del Moral Hernandez, Villegas, & Arechaga Ocampo, 2023; Koniali et al., 2020). Therefore, a survival nomogram was constructed to predict the 2 years, 3 years OS of TNBC patients with organ metastasis.
This study found that the median survival time of patients without organ metastasis was much longer than those with organ metastasis group, which was about 62 months compared to 12 months. All organ metastasis reduced the OS, including lung, liver, and brain. This was consistent with the results of Hu XC(Hu et al., 2015), that patients with metastatic TNBC typically had poor prognoses and a median survival time was about 12 months. The 2-year survival rate of the TNBC organ metastasis cohort was only 24.97%, the survival rate for 3-year was only 14.17%, and the median survival time was 12 months. What’s more, we found that bone metastasis is the most common distant metastasis site of TNBC, followed by lung, liver, and brain, which is following previous studies(Fan et al., 2023; Gu, Wu, Zou, Huang, & Yi, 2020; B. Liu et al., 2023). Additionally, the prognosis of the TNBC organ metastasis cohort was related to the location of metastasis, and bone metastasis was the best, which was consistent with the results of Lin S(Lin et al., 2021). Nevertheless, the prognosis of brain metastasis was the worst, which was about only 6 months. Yang R et al(Yang, Shi, Han, & Liu, 2021) covered that the survival time of patients who were diagnosed with TNBC brain metastasis was usually only 4 months. Considerable research showed that: age is closely related to the prognosis of TNBC. Di Leone A et al(Di Leone et al., 2023) found that TNBC occurs at a relatively young age. This was consistent with our research results. The majority of TNBC patients included in this research were aged between 41 and 60 years old, accounting for approximately 44.06%, followed by 61 to 80 years old (38.59%), with the lowest number of patients in the 18 to 40 years old (9.85%) and > 80 years old (7.51%). In addition, we further found that the older the age, the shorter the median survival time in the group with organ metastasis: the median survival time was 14, 14, 12, and 6 months at the ages of 18–40, 41–60, 61–80, and > 80, respectively. By Zheng YZ(Zheng, Wang, Fan, & Shao, 2021): older age was an independent risk factor for adverse prognosis of BC (HR: 1.671; P < 0.0001). But the median survival time was lower in TNBC patients without organ metastasis who are relatively younger, which were about 63 months in the 18–40 years old group, 67 months in the 41–60 years old group, 61 months in the 61–80 years old group, and 40 months at > 80 years old group, respectively. It was maybe young patients have lower differentiation and stronger proliferation of primary TNBC compared to elderly patients(Tzikas, Nemes, & Linderholm, 2020). Moreover, many studies found that the T stage was also associated with the prognosis of TNBC patients with organ metastasis: the lower the T stage, the higher the survival time, which was also proved in our study(De-la-Cruz-Ku et al., 2020). A great deal of research showed that surgery combined with chemotherapy, and radiation therapy, was still the main treatment method for early and metastatic TNBC(Zhang et al., 2023). Chemotherapy and surgery could significantly improve the prognosis of TNBC patients with metastasis(Cao et al., 2023; Gu et al., 2020; Hua et al., 2023). This is consistent with our research findings. We further found that whether there is organ metastasis or not, primary site surgery and chemotherapy are independent prognostic factors of TNBC patients. Receiving surgery and chemotherapy could prominently prolong patients’ OS and improve their prognosis. Failure to undergo surgery was an independent dangerous factor for TNBC patients with or not with organ metastasis (HR: 1.800, 2.047; P < 0.001), with median survival time being 9 vs 16 months and 20 vs 64 months, respectively. Not receiving chemotherapy was an independent predictor for TNBC patients with or not with organ metastasis (HR: 1.790, 1.795; P < 0.001), and the median survival time was 4 vs 14 months and 58 vs 63 months, respectively. However, radiotherapy was only an independent risk factor of prognosis of TNBC patients (HR: 1.181, P < 0.001), not an influencing factor on prognosis for TNBC patients with organ metastasis, and the presence or absence of radiotherapy has little impact on median survival time. The median survival time with or without radiotherapy in the no organ metastasis cohort and organ metastasis cohort was 64 vs 60 months and 13 vs 12 months, respectively. It was probably because radiotherapy is a relatively local and palliative treatment. Although it could effectively improve local recurrence, it did not prominently improve the survival outcomes of patients with organ metastasis(Yu, Wang, Liu, & Xu, 2023).