This study included 789 patients with breast-related lymph node metastases at baseline status who underwent NAT. Molecular Subtype, HALP, P53, and FAR were identified as predictors of T-NpCR and TpCR groups by regression analysis, and prediction models were constructed and validated. The T-NpCR group was divided into two subgroups, NpCR and DpCR, for subgroup analyses. Kaplan-Meier curves demonstrated that the TpCR group had the greatest survival for OS and DFS, followed by the DpCR group, while the NpCR group had the worst. NpCR and DpCR prediction models based on cN, HALP, FAR, molecular subtype and RMC were constructed and their predictive performance was verified in the training and validation sets.
Chen et al. showed that HR(-)HER2(+) subtype of breast cancer had the highest rate of BpCR and NpCR, and HR(+)HER2(-) subtype had the lowest rate of BpCR[18]. This indicates that the heterogeneity of different subtypes of tumors, different biological behaviors, and NAT regimens contributing to DpCR. It has been suggested that cancer cells in lymph nodes may have a tumor immune tolerance, and potential explanations include differences in chemotherapy sensitivity of metastatic tumor cells or the protective effect of the lymph node microenvironment on the tumor[19]. A study by Rene et al. showed that lymphatic dysfunction were more likely to have DpCR[20]. Previous studies have indicated that fibrinogen deposition, diminished immune response, or combination of chronic systemic diseases (e.g., diabetes mellitus) may contribute to lymphatic dysfunction. This ultimately results in the inadequate delivery of NAT drugs within the lymphatic system, or in the failure of to interact with tumor foci[21, 22]. In this study, elevating peripheral blood fibrinogen was associated with a worse pathological response status. The two predictive models developed in this study indicated that molecular subtype of breast cancer was associated with different pathological response status. The analysis of the baseline characteristics revealed that patients with HER2-positive or triple-negative types were more likely to have better pathological response. Nevertheless, the precise mechanism remains to be elucidated through further investigation. To ascertain the mechanisms underlying DpCR, more in-depth studies are needed to identify which neoadjuvant treatment strategies may transform DpCR into TpCR status. Additionally, the axillary lymph node management strategies employed for patients undergoing NAT prove pivotal in enhancing long-term survival and reducing recurrence in breast cancer patients.[23]
Peripheral blood immune cells can partially respond to the inflammatory state in the immune microenvironment, which is the theoretical basis for the hypothesis that peripheral blood inflammatory markers may predict tumor prognosis[24]. Abnormalities in coagulation can increase the risk of thrombosis and have a pro-tumorigenic effect, and indicators such as albumin and haemoglobin can reflect the overall nutritional status of the patient[25–27]. Peripheral blood inflammatory indexes have been shown in several studies to potentially predict prognostic status or NAT outcome in breast cancer[28, 29]. However, the capability of these peripheral blood parameters to predict between the three different pCR status of NpCR, DpCR, and TpCR is still unclear. Our study screened peripheral blood inflammatory indexes and clinico-pathological features that might predict pathological response status after NAT by lasso regression, univariate and multivariate regression analyses, and screened parameters that had good ability to predict the three pathological response statuses two by two. Based on these parameters we plotted nomograms, and the AUC values of the two model groups were as follows: in the T-NpCR vs TpCR group: 0.803 (95% CI: 0.761–0.846) and in the NpCR vs DpCR group: 0.74 (95% CI: 0.691–0.788). In addition, we noticed that HALP and FAR appeared in both predictive models and had a longer share of the scoring axis in the nomogram compared to other predictors in the same group. This suggests that the combination of HALP and FAR may have a better ability to predict the extent of tumor remission after NAT in breast cancer.
The HALP integrates four routinely collected indicators of immune and nutritional status and has been used as a new prognostic biomarker to predict many clinical outcomes in a variety of tumors. A meta analysis that included tumors such as gastric and cervical cancers showed that low HALP at baseline status was associated with poor prognosis of the tumor[30]. Lou et al. demonstrated that baseline HALP could be a predictor of whether or not to pCR after NAT in breast cancer. Using a cut-off value of 24.14, the OR for low HALP was 0.518 (95% CI: 0.365–0.734), and the area under the ROC curve for HALP was 0.847[31]. Another 2022 study discussed whether HALP could be used as a predictor for the presence or absence of axillary lymph node involvement, and demonstrated that the rate of axillary lymph node involvement for HALP less than 29.01 was 67.7% and 53.3% for HALP greater than or equal to 29.01 (p = 0.038)[32]. In our study, the level of HALP was significantly lower in the NpCR group than in the TpCR group (45.7 ± 19.2 VS 56.6 ± 24.2). This phenomenon is consistent with previous studies. Interestingly, the HALP level in the DpCR group were lower than which in the NpCR group (45.7 ± 19.2 VS 40.9 ± 14.7) and the difference was statistically significant. The results of univariate and multivariate regression analyses also matched this trend. This suggests that the relationship between HALP score and prognosis may not be strictly positive. Also, we noted that platelets were highest in the DpCR group, followed by the NpCR group, and smallest in the TpCR group. The peripheral blood inflammation indexes associated with platelets were broadly consistent with this trend. Apart from platelets, haemoglobin, albumin and lymphocytes could not explain this trend. This implies that platelets and the coagulation system may play a role in the formation of DpCR, making neoadjuvant therapy less responsive in a subset of patients who may achieve TpCR or making oncological treatment slightly more effective in patients who may NpCR.
FAR is a coagulation-inflammation-nutritional indicator of prognosis in a variety of solid tumors[33–37]. Since infection, blood coagulation, and so on affect plasma fibrinogen values, fibrinogen can somewhat represent the degree of inflammatory response[38]. Hwang et al. showed that patients with high FAR (cut-off value of 7.1) had a worse prognosis, and that univariate ( HR: 2.722, 95% CI: 1.659–4.468, P < 0.001) and multivariate (HR: 2.622, 95% CI: 1.455–4.724, P = 0.001) regression analyses also confirmed this[39]. Yang et al. set the cut-off value of FAR at 6.6 in their study, and survival analyses showed that high FAR implied worse OS and DFS[40]. In contrast, however, Zheng et al. reached the opposite result. This study concluded that low FAR (≤ 8.4) was protective for patients and that OS and DFS were worse with high FAR-PLR scores[41]. To date there are no studies discussing whether FAR can predict DpCR status after NAT. In our study, it was found that low FAR predict patients with better NAT responsiveness. The cut-off values of FAR were calculated from ROC curves to be 6.572 (NpCR vs. DpCR) and 5.513 (NpCR vs. TpCR) in the two groups, respectively. Unlike HALP, there was a more direct correlation between FAR and NAT outcome. That is, lower FAR indicate a better pathological response. Based on our findings, the coagulation system-related components, especially platelets and fibrinogen, may correlate with pathological response status after NAT. However, the mechanisms behind these findings still need to be supplemented and validated by further research.
Despite the encouraging results, this study has several limitations: (1) There is a lack of an external validation cohort to test the conclusions; (2) The findings of this retrospective study should be validated by further prospective studies. What’s more, further validation in larger cohorts is required before the models can be applied in routine clinical practice.