If you have kidney cancer, preoperative examinations, including ultrasound, CT, and even MRI, cannot definitively diagnose the cancer. These preoperative tests primarily provide diagnostic references. To confirm a diagnosis of kidney cancer, a biopsy via renal tumor puncture must be performed, or after surgery, the specimen should be sent for pathological examination to be definitively diagnosed based on the pathology results. This is because the pathology results clarify the type of tumor cells and their grading, making the pathological examination the final and most accurate diagnostic result.