Lei Wang

Colorectal cancer is one of the most common malignant tumors, and its incidence and mortality are increasing year by year in China. In 2018, for the first time, the FIT-DNA test was written into the expert consensus as the recommended screening technology in China. As the core technology of colorectal cancer screening, colonoscopy for right colon cancer is further supported. With the application of artificial intelligence technology in colonoscopy, the efficiency and accuracy of screening will be greatly improved. New screening technologies represented by circulating tumor cell (CTC) and individualized screening programs based on molecular genetics are future directions. As the core of colorectal cancer treatment, surgery has become quite mature. Traditional laparoscopic surgery has become an optimal choice for colorectal cancer surgery. Open surgery, robotic surgery and single-incision laparoscopic surgery have not been found superior to multiport laparoscopic surgery. The focus of surgical research is to precisely select surgical methods, and to protect normal physiological function of patients. For example, in order to reduce complications and improve quality of life in patients undergoing rectal cancer surgery after neoadjuvant radiotherapy, the "Tianhe surgery" was invented by the authors' team. Chemotherapy as the basis of colorectal cancer treatment has shown good results in many aspects: The PRODIGE-7 trial has confirmed that systemic chemotherapy is more important for colorectal peritoneal metastasis after high quality cytoreductive surgery (CRS). While the addition of hyperthermic intraperitoneal chemotherapy (HIPEC) with oxaliplatin does not result in the better overall survival (OS), but increases the risk of postoperative complications. The FOWARC study has found that the FOLFOX regimen (oxaliplatin and fluorouracil) achieved a 3-year disease-free survival (DFS) rate similar to that of neoadjuvant chemoradiotherapy, challenging the clinical value of radiotherapy. Although several studies have confirmed that total neoadjuvant therapy (TNT) can improve pathological complete response (pCR) rate and DFS of patients with colorectal cancer, we do not recommend unretricted expansion of chemotherapy. How to combine the clinical characteristics and molecular biological markers to select high-risk groups for chemotherapy, and how to use personalized medicine according to the genetic characteristics of patients, are also hot spots of current research. Immunotherapy is a game-changer in all aspects of colorectal cancer. In order to adapt to the immune therapy, the efficacy evaluation standard of solid tumors (iRECIST) has been revised. Immune score could redefine tumor clinical staging system. Both the Checkmate-142 study for advanced tumors and the NCT03026140 study on neoadjuvant treatment for early tumors showed promising results. Although no significant progress has been seen in the EGFR-targeted therapy and VEGFR-targeted therapy, new targeted drugs such as Eltanexor (ETLA, kpt -8602) and cobimetinib (MEK inhibitor) have been found to be effective in clinical studies. According to the detection results of tumor-related signaling pathways in patients, cross-guidance selection of targeted drug therapy is also the direction of research. Although the IWWD research results give a big blow to the "watch and wait" strategy, with the exploration of TNT plan, more accurate imaging efficacy evaluation and the application of immunotherapy, the "watch and wait" strategy will also receive new attention. In recent years, we have seen the rapid development of artificial intelligence technology. Although it is still in the exploratory stage in the field of medicine, it will certainly reshape all aspects of colorectal cancer diagnosis and treatment in the future, leading the research direction.

Radiation proctitis denotes the radiation damage of rectum caused by radiotherapy to pelvic malignancy. The clinical practices of radiation proctitis should be fully considered from diagnosis, treatment and prevention. In order to determine appropriate treatment strategies, the diagnosis of radiation proctitis should be based on clinical symptoms, endoscopic findings, imaging and histopathology to assess severity of symptoms and stage of disease. In terms of treatment decisions, non-surgical interventions are generally applied to relieve major symptoms and avoid serious complications. Diverting colostomy and restorative resection are the main surgical treatments for patients with recurrent symptoms. In terms of prevention, radiation proctitis should be prevented by improvement of radiotherapy technology, physical protection and prophylactic medication. This guide aims to provide guidance for the clinical practices of radiation proctitis in China.

Mitogen/extracellular signal-regulated kinase kinase-5 (MEK5) has been confirmed to play a pivotal role in tumor carcinogenesis and progression. However, few studies have investigated the role of MEK5 in colorectal cancer (CRC). MEK5 expression was determined by immunohistochemistry (IHC) in tissue microarrays (TMAs) containing 2 groups of tissues, and western blotting was used to confirm MEK5 expression in 8 cases of primary CRC tissues and paired normal mucosa. RNA interference was used to verify the biological function of MEK5 gene in the development of CRC. IHC revealed the expression of MEK5 was higher in tumor tissues (38.1 %), compared with adjacent normal tissue (8.3 %). Western blot showed that, MEK5 expression was upregulated in CRC tumor tissues compared with normal tissue. Analysis of clinical pathology parameters indicated MEK5 overexpression was significantly correlated with the depth of invasion, lymph node metastasis, distant metastasis and histological grade. Survival analysis revealed that MEK5 overexpression negatively correlated with cancer-free survival (hazard ratio 1.64, P = 0.017). RNA interference-mediated knockdown of MEK5 in SW480 colon cancer cells decreased their proliferation, division, migration and invasiveness in vitro and slowed down tumors growth in mice engrafted with the cells. MEK5 plays an important role in CRC progression and may be a potential molecular target for the treatment of CRC.