2015年 · 第24卷第02期

Dose D of TPS calculated to water in clinical applications_wand calculating the dose D to the medium_mDifferences between them will affect the results of radiotherapy plan evaluation and dose reporting, as well as the results of dose validation. Taking 10 cases of nasopharyngeal carcinoma as examples, the Monte Carlo algorithm of Monaco system was used to calculate D_mand D_wPlan. The dose information of target area and normal tissue was analyzed by DVH and intensity modulation verification software, and the difference of two dose was given, which provided some reference for clinical application.

For recurrent tumors, most patients have already undergone pre-surgical resection, chemotherapy, and radiotherapy. After initial treatment, patients are likely to be at risk of failure to reoperate, chemotherapy resistance, and radiotherapy overdose once the tumor relapses^[1]。 How to treat patients with recurrent tumors while reducing adverse treatment reactions is a challenge for us. The author carried out a feasibility study on how to use IMRT technology to carry out pulsed low-dose rate radiotherapy.

Gastric cancer is the fourth largest malignant tumor in the world and one of the most common malignant tumors in China. According to the data of China Cancer Registry Annual Report in 2012, the incidence of gastric cancer ranks second among all malignant tumors, and the mortality rate ranks third^[1]。 Chinese patients have the characteristics of "high proportion of advanced gastric cancer". About 50% of patients are advanced or locally advanced when they see the doctor, and they lose the opportunity of radical surgery. Usually, such patients have a poor prognosis, with a median survival time of only 8 to 13 months^[2,3,4,5]。 However, even if the patient undergoes radical surgery, because the vast majority of hospitals in China cannot achieve the standard D₂After lymph node dissection, the local recurrence and distant metastasis rate are still high, up to 20% ~60%^[6,7,8]。 Therefore, the role of neoadjuvant or adjuvant chemoradiotherapy is particularly important.

Radiotherapy is an effective method for treating malignant tumors, which can achieve the effect of eliminating tumors by damaging the DNA strand of tumor cells; However, radiotherapy also has a certain inhibitory effect, which may promote the invasion and metastasis of residual tumors. The increase of TGF-β level in tumor tissues caused by radiotherapy may be related to immunosuppression after radiotherapy^[1]。 Immunotherapy has gradually become an effective method for treating malignant tumors after surgery, radiotherapy and chemotherapy. It stimulates the immune system of the body, enhances the anti-tumor immunity of the tumor microenvironment, kills tumor cells and controls the tumor progression^[2]。 TGF-β is a pleiotropic factor with powerful immunoregulatory function. It can act as a tumor inhibitor in physiological state and precancerous stage, but it can promote tumor invasion and metastasis in the advanced stage of many tumors^[3]。 The combination of immunotherapy that blocks the TGF-β pathway or reduces the level of TGF-β and radiotherapy is expected to exert a synergistic anti-cancer effect.

Studies have shown that every increase of 1 Gy in conventional radiotherapy dose can increase the 3-5-year survival rate by about 1% and reduce the risk of death by 3%^[1]。 RILI is the main reason that limits the increase of radiotherapy dose for lung tumors, and the incidence of RILI in conventional radiotherapy is about 30%^[2]。 RILI includes early RP and late RF, which seriously affects the quality of life of patients. If an index or model can be found that can accurately predict the incidence and degree of RILI in individuals, reduce the occurrence of radiotherapy dose for those prone to RILI, and increase the radiotherapy dose for those less prone to RILI to increase the tumor LC rate, it will be possible to achieve individualized treatment, so that patients with lung tumors can get the most benefit from radiotherapy.