The Role of 18F-FDG PET/CT in Predicting the Neoadjuvant Treatment Response in Patients with Locally Advanced Breast Cancer

Purpose

Patients with locally advanced breast cancer (LABC) should be treated with neoadjuvant chemotherapy (NAC). Pathological complete response (pCR) is related to better disease-free survival (DFS). The best strategy for assessing the efficacy of NAC has not been established yet, but several studies have shown that 18F-FDG PET/CT is a potential imaging tool for assessing pCR. The aim of this study is to investigate the merits of 18F-FDG PET/CT imaging in predicting pCR in both axillary and breast tissue and to establish a threshold maximum standard uptake value (SUVmax) for predicting the response after completion of NAC.

Methods

A total of 186 LABC patients, treated with an NAC regimen according to tumor subtype, were retrospectively analyzed in this study. All patients underwent 18F-FDG PET/CT imaging before and after completion of NAC. PET parameters were measured in the most FDG avid breast tissue and axillary lymph nodes. We analyzed the correlation between the tumor SUVmax of the PET/CT response and the pCR after surgery. DFS was also evaluated with respect to pCR.

Results

Higher pCR rates were significantly associated with a higher tumor grade, an initial Ki-67 ≥20% (p = 0.03 and p = 0.003, respectively), a triple-negative subtype (32.9%), and a human epidermal growth factor receptor 2 (HER-2)-positive subtype (24.7%) (p < 0.001). There was a significant correlation between the pCR and a complete response in 18F-FDG PET/CT (p < 0.001). The overall sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of 18F-FDG PET/CT to determine the pCR after NAC were 100%, 72.2%, 85%, 75.2%, and 100%, respectively. We demonstrated a 1.1 cutoff SUVmax for breast tumors after NAC (OR: 3.94, 95% CI: 1.14-5.05, p = 0.004), the 18F-FDG PET/CT response to NAC (OR: 0.50, 95% CI: 0.25-0.99, p = 0.003), and the molecular subtype of breast tumors (OR: 0.58, 95% CI: 0.38-0.88, p = 0.011).

Conclusion

Our results confirm that 18F-FDG PET/CT is a useful method for predicting the NAC response in LABC.

Prognostic Significance of Metastatic Lymph Node Ratio in Patients with pN3 Gastric Cancer Who Underwent Curative Gastrectomy

BACKGROUND

Lymph node involvement is an important prognostic factor in patients with gastric cancer. The aim of this study was to determine the prognostic significance of metastatic lymph node ratio (MLNR) and compare it to the number of lymph node metastasis in pN3 gastric cancer.

METHODS

We retrospectively analyzed 207 patients with pN3 gastric cancer who had undergone radical gastrectomy. Prognostic factors and MLNR were evaluated by univariate and multivariate analysis.

RESULTS

An MLNR of 0.75 was found to be the best cut-off value to determine the prognosis of patients with pN3 gastric cancer (p = 0.001). The MLNR was significantly higher in patients with large-sized and undifferentiated tumors, vascular, lymphatic and perineural invasion, and total gastrectomy. In multivariate analysis, MLNR (p = 0.041), tumor differentiation (p = 0.046), and vascular invasion (p = 0.012) were found to be independent prognostic factors for disease-free survival, while both MLNR (p < 0.001) and pN stage (p = 0.002) were independent prognostic indicators, as was tumor size, for overall survival. There was significant difference with respect to the recurrence patterns between MLNR groups. Lymph node and peritoneal recurrences were significantly higher in patients with MLNR > 0.75 compared to the MLNR < 0.75 group (p < 0.05). However, recurrence patterns were similar between pN3a and pN3b.

CONCLUSION

Our results showed that MLNR was a useful indicator to determine the prognosis and recurrence patterns of patients with radically resected gastric cancer. Moreover, MLNR is a beneficial and reliable technique for evaluating lymph node metastasis.