Does kidney cancer diagnosis require finding tumor cells in urine?

Kidney cancer, also known as renal cell carcinoma or renal adenocarcinoma, is the most common malignant tumor of the kidney. Due to the increase in average life expectancy and the advancement of medical imaging, the incidence of kidney cancer has increased. The number of kidney cancers that are discovered accidentally during physical examinations without obvious clinical symptoms is increasing. Kidney cancer mostly occurs in people aged 50 to 70, and the incidence rate in men is more than twice that in women. The cause of kidney cancer is still unclear. Statistics show that it may be related to smoking, especially in male patients.

Diagnosis of renal cancer: 1. Medical history. 2. Physical examination. 3. Laboratory tests and imaging examinations. (1) Ultrasound examination: Ultrasound examination is simple, easy to perform, non-invasive, and has a high sensitivity in detecting renal tumors. It is the preferred examination method. Due to the widespread use of B-ultrasound examination in clinical practice, the detection rate of asymptomatic renal cancer has greatly increased. The sonogram of renal cell carcinoma can show abnormal renal section, localized echo abnormality in the renal parenchyma, and compression of the renal parenchyma. Color Doppler can show the blood flow of malignant tumors, and pulsed Doppler can effectively determine the blood flow of tumors. Arterial blood flow can be detected in 77% of renal malignant tumors. The pulsed Doppler frequency shift exceeds 25kHz, which can be used as an indicator to distinguish between benign and malignant tumors. B-ultrasound has a high sensitivity in distinguishing solid and cystic renal diseases, but it is difficult to diagnose those with a diameter of <2cm or atypical sonograms.

(2) X-ray and urography: They are not very valuable for diagnosing kidney cancer, especially when the kidney cancer is small and limited to the parenchyma. X-ray and urography may show no abnormal changes. When the tumor continues to develop, X-rays may show that the kidney has enlarged and its contour has changed. Kidney cancer may show calcification, which has a low density and appears as fine dots. It may also become calcification lines or shells around the tumor. Urography can show changes such as deformation, stenosis, elongation, and displacement of the renal pelvis and calyx caused by tumor progression and compression of the collecting system. It can also understand the function of both kidneys and the condition of the renal pelvis, ureter, and bladder, which is of great value for treatment.

(3) CT is currently the most reliable imaging examination method for diagnosing renal cancer: CT can detect asymptomatic early renal cancer. In addition to clearly showing the size and range of the tumor, it can also determine whether renal cancer has invaded adjacent organs or metastasized. CT is an ideal preoperative staging method for renal cancer, with an accuracy rate of up to 90%. Pathologically, patients with perinephric spread can be shown on CT, manifested as blurred tumor edges, thickening of the renal fascia, disappearance of the perinephric fat capsule, infiltration of the psoas major muscle, and destruction of lumbar bone. By measuring the CT value of the tumor and the change in CT value after intravenous injection of contrast agent, it can provide an important reference for the differential diagnosis of benign and malignant tumors. On plain scans, it manifests as a mass in the soft tissue of the renal parenchyma, local protrusion of the tumor, and changes in the renal contour. The CT value of renal cancer tissue is usually between 30 and 50 HU, slightly higher than that of normal renal tissue; after enhanced scanning, the CT value of the renal parenchyma reaches 120 HU, and the CT value of the tumor is also enhanced, but significantly lower than that of normal renal tissue.

(4) MRI: MRI has similar sensitivity and accuracy in the diagnosis of renal cancer as CT, and is superior to CT in showing the renal vein or inferior vena cava, surrounding organ involvement, and differential diagnosis of benign and malignant tumors. The theoretical advantages of MRI do not always provide much help in clinical diagnosis and treatment, so MRI is not a routine examination for patients with renal cancer. MRI examination is only considered when the data provided by CT and ultrasound examinations are not satisfactory for differential diagnosis and staging of tumors.

(5) Renal artery angiography: This is an invasive examination that can detect tumors in the renal pelvis and calyces that are not deformed during urography. Renal cancer is manifested by changes such as new blood vessels, arteriovenous fistulas, contrast agent pools, and increased capsular blood vessels. When adrenaline is injected into the renal artery, normal renal blood vessels and benign tumor blood vessels contract, while blood vessels in renal cancer tissue do not respond. For patients with solitary kidney renal cancer and other patients who are scheduled to undergo partial nephrectomy, renal artery angiography can provide information about the blood supply of the renal parenchyma, which is important for the selection of surgical procedures and the estimation of the blood circulation of the remaining renal tissue.

(6) Pathological examination: Renal cancer is also called renal cell carcinoma. It originates from renal tubular epithelial cells and can occur in any part of the renal parenchyma, but it is more common in the upper and lower parts, and a few invade the entire kidney; the left and right kidneys have equal chances of disease, and bilateral lesions account for . Tissues can be obtained by surgical resection, metastatic lesion biopsy, etc. Pathological classification: Renal cell carcinoma (RCC): accounts for % of adult renal malignant tumors. Including ① clear cell carcinoma: the most common; ② granular cell carcinoma: ③ undifferentiated carcinoma.