Significance of desmoplastic reactions on tumor deposits in patients with colorectal cancer.

It has been well recognized that the tumor microenvironment serves important roles in the progression and invasion of cancer. The desmoplastic reaction (DR) is a fibrous tissue reaction around tumor cells, and the prognostic significance of DR in colorectal cancer (CRC) has been established. Tumor deposits (TD) are also an important prognostic indicator of CRC. Notably, immature type DR has been linked to poor prognosis. In addition, immature type DR is significantly associated with a higher pT stage, presence of lymphovascular invasion and lymph node metastasis; however, to the best of our knowledge, the association between DR and TD has not yet been examined. The present study aimed to clarify this association. This study included 443 consecutive patients with pT3 or pT4 CRC who underwent surgical resection. The histopathological features, including DR and TD, were evaluated. Statistical analyses of the presence of TD, DR and other clinicopathological parameters were performed. The present cohort included 205 female and 238 male patients; 293 (66.1%) and 150 (33.9%) patients were classified as pT3 and pT4, respectively. Immature, intermediate and mature DR were noted in 282 (63.7%), 91 (20.5%) and 70 patients (15.8%), respectively. TD was observed in 93 (21.0%) patients. Immature type DR was significantly associated with a higher pT stage (P<0.0001), presence of lymph node metastasis (P<0.0001), lymphatic (P=0.0007), venous (P<0.0001) and perineural invasion (P<0.0001), and higher tumor budding (TB) (P<0.0001). Moreover, immature type DR was significantly associated with the presence of TD (P<0.0001). The present study demonstrated a significant association between immature type DR and the presence of TD, and suggested a close relationship between lymphovascular invasion, DR, TB and TD. Additional studies are required to analyze the detailed mechanism underlying the development of immature DR in CRC to define novel treatment strategies.