Surgery has become the standard treatment mode for early stage non-small cell lung cancer. However, what kind of treatment is the optimal solution for those patients who cannot or are not willing to undergo surgery due to advanced age, poor lung function, cardiac insufficiency, and other serious medical diseases? At present, local treatments for early stage lung cancer include microwave ablation, radiofrequency ablation, cryoablation and stereotactic radiotherapy, etc. Which technique has more therapeutic advantages in inoperable early stage non-small cell lung cancer? The principle of microwave ablation is actually the same as that of “microwave oven”, which is to cause coagulative necrosis of tumor tissues through microwave heating, so as to achieve the purpose of “burning” tumor cells. Clinical operation is to use 915MHz or 2450MHz frequency, under the guidance of CT and other imaging technologies, a microwave needle with a diameter of only 2mm is punctured into the tumor tissues through the skin, and under the action of microwave electromagnetic field, the water molecules, protein molecules and other polar molecules in the tumor tissues produce extremely high-speed vibration, resulting in the collision and friction between molecules, which generates high temperature as high as 60-150℃ in short time, thus leading to the “burning” of tumor cells. 60～150℃ in a short time, which leads to coagulative necrosis of cells. As the radiator will microwave energy concentrated in a certain range, so it can effectively radiate to the required target area to avoid damage to the surrounding important organs. Radiofrequency ablation refers to the radiofrequency transmitter generates high-frequency conversion of radiofrequency current, so that the ions in the tissues frequently oscillate with the conversion of positive and negative electrodes of the current, generating friction, converting the electrical energy into thermal energy, and increasing the temperature of the tissues, thus causing the tumor cells to undergo thermo-coagulable necrosis and denaturation. The accumulation of thermal energy exceeds the tolerance of cells and causes cell death called coagulative necrosis. Cryoablation is mainly the rapid formation of ice crystals inside and outside the cells after cooling, leading to dehydration and rupture of tumor cells. At the same time, freezing causes microvascular contraction, blood flow slowing down, microthrombus formation, blocking blood flow, leading to ischemic necrosis of tumor tissues. After repeated freezing and thawing of tumor cells, cell rupture and cell membrane dissolution prompt the release of intracellular and antigens in the masked state, stimulating the body to produce antibodies and improve immunity. Stereotactic radiation therapy (SBRT), also known as stereotactic ablative radiotherapy (SABR), is a special radiotherapy technique in which a high dose of radiation therapy is precisely projected onto an extracranial body tumor lesion so that the tumor receives a high dose and the normal tissues around the tumor receive a low dose. Its concept originated from the treatment of intracranial metastatic cancer, and the main mechanism of SBRT is that under the mediation of on-line imaging, the “killing (ablation)” radiation dose is focused on small tumors (<5cm in diameter) in a stable, precise and accurate way, so as to achieve the "stable, accurate and ruthless" radical treatment effect, and its advantages are high efficiency and non-invasive. The advantages are high efficiency and non-invasive. The effect of stereotactic radiotherapy is similar to that of a sharp scalpel cutting the lesion sharply, while at the same time maximizing the protection of the surrounding normal organs from the effects of radiation, so stereotactic radiotherapy is also commonly known as X-knife. It is like a concave mirror that focuses sunlight from different angles on a single point, which is a destructive form of radiation therapy for tumors. In 2003, McGarry of Indiana University first reported the results of a prospective clinical study of SBRT for the treatment of early-stage NSCLC, with a 2-year control rate of 95% and an overall survival rate of 55%. 2010 results of the RTOG0236 clinical trial published in JAMA showed that the 3-year disease-free survival and overall survival rates of SBRT for early-stage NSCLC were 48.3% and 55.8%, respectively. 48.3% and 55.8%, thus laying the foundation for SBRT to become the standard of care for the treatment of patients with inoperable early stage non-small cell lung cancer.In 2012, the National Comprehensive Cancer Network (NCCN) guidelines recommended SBRT as the treatment of choice for inoperable early stage non-small cell lung cancer. In 2015, Professor Yujiao Zhang of MD Anderson Cancer Center combined the results of two independent, clinical phase 3 randomized controlled studies from STARS and ROSEL to compare the efficacy of SBRT and surgical resection for the treatment of patients with surgically resectable stage I non-small cell lung cancer.The mid-term follow up time for the SBRT group and the surgical treatment group was 40.2 and 35.4 months respectively, with an evaluable 3-year survival rates of 95% and 79%, and 3-year recurrence-free survival rates of 86% and 80%. The study showed that stereotactic radiotherapy, in addition to surgery, is another treatment option for patients with resectable stage I lung cancer. The results of this study were published in the journal (LancetOncol) in 2015.In 2018, the American Society of Clinical Oncology also formally approved SBRT as the standard treatment for early stage inoperable non-small cell lung cancer. It is also currently recommended by the European, Japanese, and Chinese oncology societies as the standard treatment for early inoperable non-small cell lung cancer. Q: In many hospitals, why is microwave or radiofrequency ablation recommended for inoperable early stage lung cancer? A: Compared with stereotactic radiotherapy, microwave or radiofrequency ablation therapy requires less equipment technology, and it is easier to be promoted as a CT localization machine and an ablation instrument can be used to carry out the business. Stereotactic radiotherapy, on the other hand, is a high-precision, sophisticated technology developed over a century of radiotherapy technology, which requires not only high-end and expensive equipment, but also experienced teams of physicists, doctors and technical teams. On the whole, hospitals that can implement stereotactic radiotherapy technology are generally very experienced specialized hospitals in China, so it is not very convenient to promote the technology.