Kidney tumor is one of the common tumors in the urological system. After bladder cancer, kidney cancer is the second most malignant tumor in the urological system, accounting for about 2%~3% of all malignant tumors in adults. With the increase of life expectancy and the improvement of examination technology, the trend of clinically detected cases is increasing. I think the pollution of environment and food also has a certain relationship. Due to the location of renal parenchymal tumor, its symptoms appear much later than epithelial tumor of renal pelvis. In the past, due to the reason of diagnostic technology, there was a clinical phenomenon that renal pelvis tumor is more than renal parenchymal tumor in China. Now it is confirmed that renal parenchymal tumors are far more common than renal pelvic tumors in China. Due to the progress of the country and the soundness of the health care medical examination system, the number of renal tumors detected through ultrasound has increased significantly, and most of those detected early are incidental cancers, so the mortality rate has also decreased significantly. The cause of kidney tumor is still unclear, epidemiologists have made a lot of investigation and found that the following factors may be related to the development of kidney tumor. 1.Smoking: a large number of prospective observation of the relationship between kidney cancer and smoking, smoking is a moderate factor, smoking is positively correlated with kidney cancer and also positively correlated with the amount of smoking. 2.Obesity: obesity is positively correlated with kidney cancer. A large number of case analysis obviously shows that the risk of kidney cancer increases with weight, and obesity is a risk factor of kidney cancer. 3.Occupation: Cadmium industry, steel, coke, petroleum, printing and dry cleaning workers have high incidence. It has also been reported that asbestos workers are prone to kidney cancer. 4.Urban and rural areas, culture and economic status: there are reports that the incidence of kidney cancer is also high in high culture and economic status. Urban incidence rate is higher than rural incidence rate. 5.Alcohol consumption and food: Alcohol consumption is not related to kidney cancer incidence. Inadequate intake of VITA may increase the risk of kidney cancer in humans. It is also believed that the aluminum content in water is related to kidney cancer. 6. Hormones and drugs: estrogen may be related to renal cortical cancer. Calcium intake may reduce the occurrence of kidney cancer. Abuse of painkillers, especially those containing fexofenadine, is prone to renal pelvis cancer. It is also known that diuretics have an increased risk of kidney cancer. 7.Other: People with diabetes are prone to kidney cancer. Those who are on long-term dialysis for more than three years due to renal insufficiency are prone to kidney cancer. Diagnosis and differential diagnosis of kidney cancer: Generally, it is not difficult to make the diagnosis of kidney cancer based on the clinical data, but false positive and false negative diagnosis does occur from time to time. Comprehensive and careful analysis is the basis of accurate diagnosis. The kidney is located in the retroperitoneum surrounded by intraperitoneal organs and abundant lumbar and dorsal muscles; therefore, kidney tumors often lack early clinical manifestations. Traditionally, the “triad of kidney cancer” consisting of hematuria, pain and abdominal mass are all symptoms of advanced lesions. In fact, most patients exhibit only one or two of these symptoms, with about 10% having all three. However, it is noteworthy that renal cell carcinoma may present with multiple “extra-renal manifestations”, which are easily confused with other systemic diseases, but at the same time, these symptoms are often the reason why patients come to the clinic. In addition, it is not uncommon for a patient to come to the clinic with metastatic symptoms and be found to have kidney cancer. At present, there are more cases of kidney cancer detected by ultrasound without any symptoms, but further examination confirms it to be kidney cancer. (I) Symptoms and signs 1. Hematuria: The incidence rate is about one of the most common clinical symptoms of kidney cancer as the kidney is connected with the outside world through urine. However, the occurrence of hematuria is no longer an early symptom of kidney cancer, which means that the tumor has invaded the mucosa of renal pelvis or renal calyx. Hematuria is often intermittent and visible to the naked eye throughout the whole process, and sometimes there are streaks of blood clots. When the blood clot blocks the ureter, it can cause renal colic. 2.Pain: The incidence of pain is about 1.5 times, mostly in the abdomen, mostly dull pain. The cause is not only the tumor growth stretching the kidney peritoneum, but also due to the tumor invading the surrounding organs or lumbar muscle, the latter pain is often heavy and lasting. The latter kind of pain is often severe and long-lasting. Renal colic may occur when blood clots are formed due to serious hematuria and ureteral obstruction. 3.Mass: About 20% of kidney masses are more likely to appear in long and lean body types. The masses are located under the rib cage in the upper abdomen and can move up and down with breathing movement. The mass that can be palpated by the examiner may be the tumor itself or the lower pole of the kidney that has been pushed by the tumor. If the mass is immobile, this indicates that the tumor has invaded the surrounding organ structures of the kidney. In this kind of patients, it is difficult to remove the tumor and the prognosis is not good. 4.Extra-renal manifestation: about 20%. As the kidney is an important metabolic organ, it is also an endocrine organ, which can synthesize and secrete prostaglandin E1, 25-dihydroxyvitamin D3, renin and erythropoietin under normal conditions. When renal cell carcinoma is present it can secrete much higher than normal levels of these hormones, as well as substances such as parathyroid-like factor, hyperglycemia, human chorionic gonadotropin and insulin. This results in a wide variety of extra-renal systemic symptoms of kidney cancer. These symptoms, except hypercalcemia, are difficult to be cleared by conventional treatment, however, after removal of the primary focus, the indicators can mostly return to normal. 1) Fast blood sedimentation: the incidence is about 50%. The reason for this is not clear, but even 6 years before the diagnosis of kidney cancer, there is already an increase in blood sedimentation, so it is suggested that patients with persistent fast blood sedimentation should have renal ultrasound examination to exclude renal tumor. 2) Fever: the incidence is about 20%. It has been found that 20% of the primary tumors can ectopically secrete interleukin-6, and this ectopically secreted interleukin-6 may be related to fever. (3) Hypertension: the incidence is 20%. As mentioned before, hypertension and drugs used to treat hypertension are associated with the occurrence of kidney cancer. Therefore, hypertension can be said to be caused by kidney cancer only when normalcy is restored after removal of kidney cancer. Excessive secretion of renin, arteriovenous fistula within the tumor, and compression of renal blood vessels by the tumor may all be the causes of hypertension. 4) Hypercalcemia: the incidence is 10%. This may be related to a peptide similar to parathyroid hormone-related protein produced by the tumor. It may also be related to tumor metastasis to the bone marrow. It returns to normal after removal of the tumor and may be re-elevated by tumor metastasis or recurrence. 5) Erythrocytosis: It may be related to direct secretion of erythropoietin by tumor or tumor compression causing ischemia of normal renal tissue and stimulating secretion of erythropoietin. 6) Abnormal liver function. It is not caused by tumor metastasis to the liver. The patient also has leukopenia, fever and local necrosis of the liver. Liver function is normalized after removal of renal tumor. In rare cases, it may also be accompanied by cholestatic jaundice. (7) Others: anemia, decreased body temperature, elevated serum alkaline phosphatase, amyloidosis and neuropathy may occur in patients with renal cancer. 5) Varicose veins of the spermatic cord. Characterized by not disappearing after lying down, caused by compression of renal vein or inferior vena cava and tumor thrombus in renal vein or inferior vena cava obstructing blood return in the spermatic vein. 6.Metastasis. Kidney tumor metastasis is early and multi-located. About 20~35% of kidney cancer patients have metastasis when they visit the doctor, and another 6~15% of patients come to the doctor because of the symptoms of metastasis. For abnormal masses appearing in any part of the body, especially those of unknown origin, the possibility of kidney cancer metastasis should be thought of. 7. Accidental discovery. It is discovered “accidentally” during physical examination or examination of other diseases, which accounts for more than 30% of the current kidney cancer patients. (2) Diagnosis of kidney cancer When evaluating a patient with hematuria, back pain or abdominal mass, we should ask whether there are systemic symptoms such as weight loss and fever. Hematuria with streaky blood clots suggests that the bleeding occurs in the upper urinary tract. The presence of hypertension and supraclavicular lymphadenopathy should be noted during physical examination. A lumbar rib or abdominal mass may be accompanied by a murmur. A right spermatic varicocele that does not disappear when lying flat suggests the possibility of vena cava aneurysm embolism. Standard laboratory tests should include complete blood counts, coagulation tests, and serum biochemistry. A bone scan is required in the presence of elevated serum alkaline phosphatase or symptoms of bone pain. The preoperative diagnosis of kidney cancer depends on the results of imaging examination, which can provide the most direct diagnostic basis. CT scan is the best method to understand the location, scope, nature and metastasis of tumor, so it is the most reliable tool to diagnose kidney cancer. Smaller tumors usually do not need to be examined regarding the vena cava. Nowadays, MRI is more commonly used to understand whether the tumor involves the vena cava or not and to make differential diagnosis. Cystoscopy should be done when there is hematuria. Renal arteriogram is useful for the diagnosis of renal cancer, especially selective or super-selective renal artery embolization can be performed at the same time, which is beneficial to the future surgery. (iii) Differential diagnosis of renal cancer In the differential diagnosis, it is also necessary to differentiate from renal cyst, renal malformation tumor, renal lymphoma and yellow granuloma of the kidney. Generally speaking, it is not difficult to differentiate these diseases with the help of symptoms and imaging examination. If they cannot be identified, then surgery is necessary. Treatment of kidney cancer: Once diagnosed, the best treatment for kidney tumor is radical nephrectomy. If the kidney is in advanced stage, palliative simple nephrectomy should also be performed. In some specific cases such as isolated kidney, contralateral renal insufficiency, bilateral renal cancer, etc., partial nephrectomy or renal tumor excision can be considered. Most renal tumors are not sensitive to radiotherapy and chemotherapy after surgery, so immunotherapy can be given. However, those with advanced tumor or post-operative recurrence or distant metastasis that cannot tolerate surgery can be considered for chemotherapy or radiotherapy, or renal artery embolization + missile therapy. At present, we have to remind you that the incidence of kidney cancer is significantly more than before, early detection should be early medical examination, and surgery is the best treatment means.