Tumor microenvironment and radioresistance

Metastasis is not the result of a random event, as cancer cells can sustain and proliferate actively only in a suitable tissue microenvironment and then form metastases. Since Dr. Stephen Paget in the United Kingdom proposed the seed and soil hypothesis of cancer metastasis based on the analogy that plant seeds germinate and grow only in appropriate soil, considerable attention has focused on both extracellular environmental factors that affect the growth of cancer cells and the tissue structure that influences the microenvironment. Malignant tumor tissues consist of not only cancer cells but also a wide variety of other cells responsible for the inflammatory response, formation of blood vessels, immune response, and support of the tumor tissue architecture, forming a complex cellular society. It is also known that the amounts of oxygen and nutrients supplied to each cell differ depending on the distance from tumor blood vessels in tumor tissue. Here, we provide an overview of the tumor microenvironment and characteristics of tumor tissues, both of which affect the malignant phenotypes and radioresistance of cancer cells, focusing on the following keywords: diversity of oxygen and nutrient microenvironment in tumor tissue, inflammation, immunity, and tumor vasculature.

Ovarian Cancer-Associated Mesothelial Cells: Transdifferentiation to Minions of Cancer and Orchestrate Developing Peritoneal Dissemination

Ovarian cancer has one of the poorest prognoses among carcinomas. Advanced ovarian cancer often develops ascites and peritoneal dissemination, which is one of the poor prognostic factors. From the perspective of the “seed and soil” hypothesis, the intra-abdominal environment is like the soil for the growth of ovarian cancer (OvCa) and mesothelial cells (MCs) line the top layer of this soil. In recent years, various functions of MCs have been reported, including supporting cancer in the OvCa microenvironment. We refer to OvCa-associated MCs (OCAMs) as MCs that are stimulated by OvCa and contribute to its progression. OCAMs promote OvCa cell adhesion to the peritoneum, invasion, and metastasis. Elucidation of these functions may lead to the identification of novel therapeutic targets that can delay OvCa progression, which is difficult to cure.

Metastasis Kanker Paru

Metastasis is the ability of cells to escape from the primary tumor, then enter the circulation to the distant tissue and form a secondary tumor. There are hemodynamic hypothesis (anatomical) and seed and soil hypothesis (molecular recognition). Tumor cells spread through several ways: percontinuitatum, lymphogen, hematogenous, transluminal, transcelomic, and iatrogenic. The stages of the metastasis process include: detachement, invasion, intravasation, circulation, extravasation, and angiogenesis. Predilection of lung cancer metastasis often happens in the brain, bones, liver, and adrenal glands. The spread of lung cancer metastasis to the brain, bone, and liver occurs hematogenously. Adrenal glands metastasis ipsilateral occurs lymphatically, while contralateral occurs hematogenously. Lung cancer is often diagnosed at an advanced stage, because in the early stage it is often asymptomatic. Metastasis of lung cancer to distant organs is the most cause of lung cancer deaths.

Understanding the Rare Krukenberg Tumor: A Current Review

Krukenberg tumors represent a rare type of secondary ovarian tumors composed of mucinous signetring cells. In up to 70% of cases the primary site is a diffuse type gastric carcinoma, which disseminates to the ovary through a retrograde lymphatic pathway. The Krukenberg tumor is a good example of metastatic ovarian organotropism (“seed and soil” hypothesis).The symptoms are nonspecific and usually don’t develop until the tumors reach a certain size. The definitive diagnosis can only be made histologically after surgical resection, although imaging findings can indirectly aid in the distinction between benign-malignant and primary-secondary tumors. Immunohistochemistry is the most important diagnostic method in distinguishing primary from secondary ovarian neoplasms, and can usually detect the tissue of origin. The extremely dismal prognosis of Krukenberg tumors is attributed to the fact that they represent an advanced stage metastatic disease. Although the standard treatment is systemic chemotherapydepending on the primary site, there are rough indications that cytoreductive surgery might prolong survival in selected patients.