Kidney cancer, also known as renal cell carcinoma and renal adenocarcinoma, originates from the urinary tubular epithelium. Kidney cancer accounts for 80%-90% of adult malignant tumors, and is the most common kidney tumor in adults. The ratio of male to female is about 2:1, and it can be seen in all age groups, with a high incidence at the age of 50-70. With the popularization of medical checkups, more and more early kidney cancers have been diagnosed in time. Not smoking and avoiding obesity are important methods to prevent the occurrence of kidney cancer. Disease classification Currently, kidney cancer is divided into 10 types: renal clear cell carcinoma, papillary renal cell carcinoma (type I and II), renal suspensory cell carcinoma and unclassified renal cell carcinoma, Bellini’s collecting duct carcinoma, medullary carcinoma, multifoveal cystic renal cell carcinoma, Xp11 translocated renal carcinoma, carcinoma associated with neuroblastoma, mucinous tubular and spindle cell carcinoma subtypes. Renal clear cell carcinoma is the most common, accounting for approximately 90% of cases. Causes The causes of kidney cancer are unknown. Possible causes include: Smoking: A large number of prospective observations have found a positive association between smoking and kidney cancer development. Obesity and hypertension. High body mass index (BMI) and hypertension are two independent factors associated with an increased risk of kidney cancer development in men. Occupation: Increased risk of kidney cancer incidence and death has been reported in workers with long-term exposure to metallic cadmium and lead, newspaper printers, coke workers, dry cleaners and petrochemical workers. Radiation: Long-term exposure to certain weak radiation sources may increase the risk of kidney cancer. Inheritance: The identified hereditary kidney cancers include: (i) VHL (retinal and central neurovascular hemangioblastomatosis) syndrome; (ii) hereditary papillary kidney cancer; (iii) hereditary smooth muscle tumor disease kidney cancer; and (iv) BHD syndrome (a dominantly inherited syndrome). Dietary factors: The survey found that high intake of dairy products, animal protein and fat and low intake of fruits and vegetables are risk factors for kidney cancer. Foods and drugs that may increase the risk of kidney cancer: coffee, female hormones (estrogen), antipyretic and analgesic drugs, especially those containing finasteride, diuretics and red vine herb, also known as “Chiken”, etc. In patients on long-term maintenance hemodialysis, there has been an increase in the number of kidney cancer cases. Therefore, those who have been on dialysis for more than 3 years should have their kidneys examined by ultrasound every year. It has been reported that diabetic patients are more likely to develop kidney cancer. Among kidney cancer patients, 14% of them have diabetes, which is 5 times more than that of the normal population. Pathogenesis The pathogenesis of kidney cancer is not fully understood. According to current research, kidney cancer is a malignant tumor with a unique pathogenesis, and the mechanism of occurrence is extremely complex. The pathway of dissemination: the tumor grows gradually and can directly invade the renal pelvis, calyces, and even ureters. Cancer cells can penetrate the renal peritoneum and invade the adrenal glands and perinephric adipose tissue. In addition, renal cancer often invades the renal vein, and some of them form strips in the lumen of the vein to extend to the lower vena cava and even to the right atrium. Since cancer tissue is rich in blood vessels, blood metastasis can occur at an early stage, most often to the lung, bone marrow and the opposite kidney. Lymphatic metastasis often first reaches the hilum and para-aortic lymph nodes. Clinical manifestations Most common people Family history of hereditary kidney cancer; middle-aged or older “fat” men who smoke, drink heavily and suffer from high blood pressure. Disease symptoms For many years, hematuria, pain and lumps are called “triad signs” of kidney cancer, but in fact, most patients with all three signs at the time of consultation only account for about 10%, and few of them are likely to be cured. Therefore, it is very necessary to have a comprehensive understanding of some common clinical manifestations of kidney cancer. No obvious symptoms: At present, more than 40% of kidney cancers are found accidentally due to health checkup or other reasons, without obvious symptoms or signs, and their detection rate is increasing year by year, most of them are early lesions with good prognosis. Regular physical examination is important. Typical local symptoms: hematuria, lumbar pain and abdominal lump are the “triad of kidney cancer”, which has a clinical occurrence rate of <15% and often indicates that the lesion is at an advanced stage. Most patients only have one or two of these symptoms. Hematuria: About 40% of patients with kidney cancer have hematuria, which can be either visual or microscopic hematuria. In case of massive hematuria and clot formation, renal colic, painful urination, difficulty in urination and even urinary retention may occur. Mass: The kidney is located in the retroperitoneum and deep, so it cannot be palpated during abdominal palpation. Only when the tumor is large or located in the lower pole of kidney can the mass be palpated. Pain: Low back pain occurs due to the increase of renal peritoneal tension or invasion of surrounding tissues after the tumor grows up, and it manifests as continuous dull pain. Dull pain or vague pain may also occur due to subperitoneal hematoma caused by tumor bleeding. Tumor invasion of adjacent tissues and organs, such as lumbar muscle or nerves, may cause persistent and severe low back pain. The incidence of pain is 20% to 40%. If the tumor invades the adjacent tissues and organs such as lumbar muscle or nerves, it may cause continuous and severe back pain.