Pancreatic cancer is characterized by increased hyperplasia of fibrotic tissue, termed desmoplasia, and lymph node metastasis is an independent prognostic factor in this disease. However, there are no reports focused on desmoplasia in pancreatic cancer lymph node metastases. The present study evaluated a range of factors and investigated their association with poor prognosis in pancreatic cancer cases with lymph node metastasis, including the degree of desmoplasia in lesions. To identify the poor prognostic factors associated with lymph node metastasis, the present study retrospectively reviewed the clinical data of 65 patients with lymph node metastases that underwent surgical pancreatic cancer resection between 2007 and 2012 at a single institution. The investigation focused on the degree of fibrosis in metastatic lesions in 216 lymph nodes, and investigated associations with prognosis or clinicopathological findings. The ratios of the fibrotic area in metastatic lymph node lesions were evaluated and classified into three categories, high (≥70%), moderate (10-70%) and low (<10%). Desmoplasia was not observed in cancer-free lymph nodes. The size of metastatic lymph node lesions was additionally measured, and a significant association between metastatic lesion size and the degree of desmoplasia was observed (P<0.001). The degree of desmoplasia was additionally associated with local extranodal invasion. In the analysis of 65 pancreatic cancer patients with metastatic lymph nodes, the presence of multiple metastatic lymph nodes with moderate or high desmoplasia was significantly associated with poor survival (high, P=0.0048; moderate/high, P=0.0075). Of several clinicopathological factors, the presence of multiple metastatic lymph nodes with high or moderate desmoplasia was associated with overall survival in univariate (P=0.0098) and multivariate (P=0.0466) analyses. The degree of desmoplasia in metastatic lymph nodes is associated with lesion size, and the presence of multiple metastatic lymph nodes with desmoplasia is an independent poor prognostic factor, suggesting that the desmoplasia may have an important role in the malignant progression of lymph node metastases.
Keywords: desmoplasia; locally extranodal invasion; lymph node metastasis; pancreatic cancer; prognostic factor.