Classic kidney cancer symptoms include:
① Hematuria, or blood in the urine;
②Abdominal pain, pain in the area of the kidney, or rib cage;
③Palpable abdominal mass, meaning that the patient or the doctor can palpate the mass through the skin.
The above 3 points can be called the “triad” of kidney cancer, but only 6% to 7% of kidney cancer patients currently have these symptoms, and they are often diagnosed at an advanced stage. Other possible symptoms include:
- Weight loss, fever, night sweats, loss of appetite, weakness, swelling of the lower extremities, and other common symptoms of malignancy;
- Symptoms directly caused by cancer metastasis, such as chronic cough caused by lung metastasis, bone pain caused by bone metastasis, jaundice caused by liver metastasis, etc.
However, most patients with kidney cancer do not have specific symptoms, and many patients are only found to have tumors in their kidneys during physical examinations in clinical practice. An analysis of data from several hospitals in China showed that asymptomatic kidney cancer accounted for 62.7%. The most common symptoms for patients are, in order, back pain, hematuria, hypertension, and anemia (see below).
In addition, about 10% to 40% of patients with symptomatic kidney cancer develop paraneoplastic syndrome.
Paraneoplastic syndrome
Paraneoplastic syndrome literally means tumor-related syndrome and is mainly due to the protein produced and secreted by the kidney cancer into the bloodstream, resulting in one or more of the following symptoms:
- Hypercalcemia, or a rise in calcium ions in the blood. This can lead to weakness, decreased body mass, slowed reactions, and altered mental status.
- Erythrocytosis, a rise in red blood cell count (as opposed to anemia), can lead to blood clotting or embolism in severe cases.
- Diabetes mellitus, in which blood glucose exceeds the normal range, occurs in 10% to 20% of cases.
- Hypertension, which may be related to hormones secreted by kidney cancer (such as renin) that raise blood pressure.
- Impaired liver function without liver metastases, also known as Stauffer’s syndrome, may occur in 10 to 15% of patients.
Early detection
Since there are no obvious symptoms in the early stages of kidney cancer, it is important to detect it early by screening.
Clinically, kidney cancer can be detected by ultrasonography, which can detect whether the tumor penetrates the peritoneum, perirenal fatty tissue, whether there are enlarged lymph nodes, whether there are cancer clots in the renal vein and inferior vena cava, and whether there are metastases in the liver. However, ultrasound examination also has certain limitations, and the accuracy of the examination is closely related to the skill and experience of the examiner.
So, after ultrasound examination reveals a renal occupancy, further enhanced CT or MRI examination is always needed to verify it.