Comparative Study of the Colon Adenocarcinoma Stroma Before and after Neoadjuvant Radiotherapy

Recently, the role of the stromal component in understanding tumor progression and clinical outcome has increased. With the tumor development and antitumor treatment, transformation of normal stromal compartments, a change of the stromal cells activity, the production of cytokines and growth factors that contribute to an increase of cancer progression and invasion can occur. Therefore, the state of the intratumoral stroma is an important prognostic criterion for malignant growth. Features of the microenvironment influencing on the progression of colon cancer are still poorly understood.The aim of this study was to identify the features of the structural organization of the colon adenocarcinoma stroma before and after a course of neoadjuvant radiation therapy.Tumor tissue samples from 31 patients with primary stage II adenocarcinomas (pT3 and pT4) of the rectum were studied using light and electron microscopy. The patients were divided into 2 groups: those who received a course of neoadjuvant radiation therapy (NART) and those who did not receive NART. It was shown that tumor samples from patients treated with neoadjuvant radiotherapy, compared with those who did not receive it, had structural signs of fibroblast activation and fibrosis. A decrease of blood microvessels volume density and a greater degree of vasculogenic mimicry were revealed. In endotheliocytes of blood capillaries, a decrease volume density of luminal, basal caveolae and transport vesicles was noted. The important role of the stromal component in the tumor progression makes it necessary to search for stromal factors to predict the course of colon cancer.