OVERVIEW

What types of kidney tumors are there?

Kidney tumors are mostly malignant. Clinically, the most common types are divided into three categories: renal cell carcinoma, Wilms' tumor, and renal pelvis tumor, with renal cell carcinoma being the most prevalent.

Are kidney tumors common?

Urological tumors account for about 2%–3% of all malignant tumors (not particularly common). Among urological tumors, bladder cancer is the most frequent, followed by kidney cancer.

What is renal cell carcinoma?

Renal cell carcinoma, also known as kidney cancer or renal adenocarcinoma, refers to an epithelial cell tumor originating from the renal tubules (including renal tubules and collecting ducts) in the renal parenchyma (which contains numerous urinary tubules and a small amount of connective tissue, blood vessels, and nerves). It is the most common malignant kidney tumor, accounting for about 80%–90% of renal malignancies.

Kidney cancer often occurs in a single kidney and is usually solitary, with no significant difference between the left and right sides. It may present with the classic triad of hematuria, pain, and an abdominal mass.

Surgical resection is the preferred treatment. Early-stage kidney cancer has the potential to be "cured."

Is kidney cancer more common in men or women?

Most urological tumors are more common in men, and kidney cancer is no exception. Male patients are about twice as likely as female patients, with the peak incidence occurring between the ages of 50–70.

SYMPTOMS

What are the specific clinical manifestations of kidney cancer?

• Kidney cancer has three classic manifestations, collectively referred to as the "renal cancer triad," which are:

  • Hematuria: The passage of red urine containing blood, often intermittent (comes and goes), painless (no pain during urination), and total (blood is present throughout the entire urination process). Occasionally, it may be accompanied by long, worm-like blood clots. However, the severity of hematuria is not proportional to the size of the kidney cancer.
  • Pain: Dull pain on the affected side of the kidney, usually tolerable. However, when blood clots block the ureter, it may cause severe, colicky pain on the affected side. If the cancer breaks through the renal fascia and invades surrounding organs, persistent pain and discomfort may occur.
  • Abdominal mass: The kidneys are located deep in the body, making them difficult to palpate under normal circumstances. A mass may be felt in the lower back or abdomen only when the kidney cancer has grown to a large size.

Early-stage kidney cancer lacks specific symptoms (meaning there are no special signs to definitively diagnose kidney cancer). However, when the renal cancer triad appears simultaneously or any single symptom occurs, it usually indicates that the cancer has progressed to an advanced stage. With increased awareness of health check-ups, the simultaneous appearance of all three symptoms is now rare.

• Paraneoplastic syndrome: Also known as extrarenal manifestations, these are symptoms caused by substances produced by kidney cancer that affect organs other than the kidneys or metastatic sites. These symptoms are nonspecific and may include fever, hypertension, weight loss, and abnormalities in blood tests (e.g., blood count, biochemistry). They have no diagnostic significance for kidney cancer.
• Metastatic symptoms of kidney cancer: When kidney cancer metastasizes, symptoms related to the affected organs may appear, such as coughing or hemoptysis (indicating lung metastasis) or pathological fractures (indicating bone metastasis).

What are the metastasis pathways of kidney cancer?

The metastasis pathways of kidney cancer are similar to those of most tumors and commonly include three types: hematogenous spread, lymphatic spread, and direct extension.

• Hematogenous metastasis (most common): Cancer cells spread through the bloodstream to other organs. The lungs are the earliest site of metastasis, followed by bones, liver, and brain.
• Lymphatic metastasis: Kidney cancer cells can spread through lymphatic vessels to nearby lymph nodes (e.g., renal hilum, retroperitoneal lymph nodes) or distant lymph nodes (e.g., mediastinal, pelvic lymph nodes).
• Direct extension: When kidney cancer breaks through the renal fascia, it can invade surrounding organs. Due to anatomical differences, the affected organs vary between the left and right kidneys. The left kidney may spread to the spleen, pancreas, or parts of the colon, while the right kidney may spread to the liver or parts of the colon.

CAUSES

What are the causes of kidney cancer?

The exact cause of kidney cancer remains unclear, but the most common possible factors include:

• Smoking: The most significant risk factor. The longer and heavier the smoking history, the higher the likelihood of developing the disease.
• Genetics: Tumors caused by this factor are often bilateral and multifocal, frequently accompanied by a family history of kidney cancer in close relatives.
• Other factors: Obesity, hypertension, and occupational exposure (prolonged contact with petroleum products, heavy metals, etc.).

Is kidney cancer hereditary?

Current research indicates that confirmed hereditary or familial kidney cancer accounts for about 2%–4% of cases. The majority of kidney cancers show no clear hereditary pattern, but individuals with a family history of kidney cancer do have a higher risk than the general population, though the exact reasons remain unknown.

Therefore, if a close relative has kidney cancer, regular medical check-ups are recommended. Seek immediate medical attention if suspicious symptoms or signs appear.

DIAGNOSIS

What tests are needed to diagnose kidney cancer? Why are these tests performed?

• Urinalysis: A preliminary test to check for red blood cells, white blood cells, etc., in the urine. However, the presence or absence of red blood cells cannot definitively confirm kidney cancer; it only serves as a reference.
• Kidney function test: A blood test that assesses the overall function of both kidneys. Even individuals with only one kidney may have normal kidney function. This test helps guide treatment decisions.
• Urine cytology: Involves examining urine samples for tumor cells. Typically, samples are collected over three consecutive days. The detection rate is low, with only a very small number of patients showing tumor cells, so it is not routinely used in clinical practice.
• Tumor markers: Currently, there are no specific tumor markers for diagnosing kidney cancer.
• Urinary system ultrasound: A non-invasive, convenient test that requires a full bladder for better clarity. It can show the location, number, and size of tumors, as well as detect urinary stones or hydronephrosis. However, it can only identify tumors larger than 0.5 cm, and accuracy increases with tumor size.
• KUB + IVP: Kidney-ureter-bladder X-ray (KUB) + intravenous pyelography (IVP). KUB has limited diagnostic value for kidney cancer and lacks specificity but can detect urinary stones and assess kidney contours and position. IVP involves injecting a contrast agent intravenously, which is excreted in urine and visualized under X-ray to show the structure of the kidneys, ureters, and bladder. It helps evaluate kidney excretion and identify potential masses. This test is time-consuming and not essential for diagnosing kidney cancer.
• CT scan of the urinary system (non-contrast + contrast-enhanced): A convenient, non-invasive test that also requires a full bladder. It can detect nearly all kidney cancers and has a high accuracy rate in determining tumor characteristics.
• MRI: A radiation-free test, but it is expensive, time-consuming, and unsuitable for individuals with magnetic implants or claustrophobia. However, it is slightly more effective than CT for kidney cancer staging.
• Kidney tumor biopsy: Involves extracting a small tissue sample for pathological examination to determine the nature of the tumor. Due to advancements in CT and MRI imaging and the risks of complications like bleeding or infection, this test is not routinely used for diagnosing kidney cancer.

Of course, the above tests are primarily used for diagnosing kidney cancer. Before surgical treatment, additional tests such as complete blood count, coagulation tests, and electrocardiogram are often required to assess surgical feasibility.

Can kidney cancer be preliminarily diagnosed after these tests?

Yes, these tests can provide a basic diagnosis of kidney cancer, but the final confirmation relies on postoperative pathology.

What are the pathological types of kidney cancer?

Kidney cancer is a general term, and further classification is based on postoperative pathology. Common types include:

• Clear cell renal cell carcinoma: The most common type, named for its transparent appearance under the microscope due to dissolved fat in paraffin during pathological examination.
• Chromophilic renal cell carcinoma: Also known as papillary renal cell carcinoma, generally has a good prognosis.
• Chromophobe renal cell carcinoma: Also typically has a favorable prognosis.
• Collecting duct carcinoma: Rare but has a poor prognosis, with an average survival of about 1 year.

TREATMENT

If you suspect kidney cancer, which department should you visit at the hospital?

If symptoms suggestive of kidney cancer appear, seek medical attention immediately for a clear diagnosis. Early detection is the most critical factor in improving treatment outcomes for all malignant tumors.

You should visit the urology or nephrology department at a local reputable hospital. Generally, outpatient visits should begin with diagnostic tests to confirm the condition. If kidney cancer is diagnosed, hospitalization for further treatment will follow.

Do not self-medicate without a clear diagnosis or take traditional Chinese medicine, supplements, or even health products without proper examination and diagnostic support, as this may delay treatment and miss the optimal window for intervention.

How is kidney cancer staged and graded?

The internationally recognized staging system for kidney cancer is the TNM classification:

• T indicates tumor size and invasion of adjacent organs;
• N refers to the status of regional lymph node metastasis;
• M denotes distant metastasis.

The subscripts for T, N, and M indicate severity—higher numbers signify worse conditions and later stages. Different TNM combinations correspond to stages IA, IB, II, III, or IV, with IA and IB being early-stage and IV being advanced-stage kidney cancer.

How is kidney cancer treated?

Treatment varies based on the TNM stage (early, intermediate, or advanced kidney cancer):

• Early-stage: Surgery is the primary option, including radical nephrectomy or nephron-sparing procedures (partial nephrectomy, tumor enucleation). Minimally invasive treatments (e.g., radiofrequency or cryoablation) are alternatives for high-risk surgical candidates but remain under clinical investigation with uncertain long-term efficacy. Postoperative adjuvant therapies lack standardization.
• Intermediate-stage: Radical nephrectomy is preferred, though adjuvant therapies post-surgery are not standardized.
• Advanced-stage: Systemic therapies (immunotherapy, chemotherapy) are mainstays, supplemented by surgery (e.g., cytoreductive nephrectomy).

What are the side effects and precautions of chemotherapy?

Chemotherapy is a systemic treatment that indiscriminately targets both cancer and healthy cells, causing side effects. Common adverse effects in kidney cancer chemotherapy include myelosuppression (low white blood cells, anemia), hair loss, nausea, vomiting, neuropathy, and liver/kidney damage.

Regular blood tests monitor myelosuppression, while liver/kidney function tests and antiemetics manage other risks. Maintain hydration, light meals, and bowel regularity during treatment. During breaks, focus on nutrition, moderate exercise, and mental well-being.

What is the life expectancy for kidney cancer patients?

Survival is measured by 5-year rates: Stage I exceeds 90%, Stage II >80%, Stage III >60%, and Stage IV <30%. Early diagnosis and treatment are pivotal for prolonging survival.

Overall, kidney cancer prognosis is better than lung, colon, or stomach cancers. Patients should pursue timely, evidence-based treatment for tangible survival benefits.

What factors affect kidney cancer survival?

Key determinants are pathology and stage. Additional factors include:

• Elevated LDH (>1.5× normal)
• Anemia
• Hypercalcemia (>2.5 mmol/L)
• Early recurrence (<1 year)
• Poor performance status
• ≥2 metastatic sites

What influences kidney cancer prognosis?

TNM stage is paramount, alongside histological grade, symptoms, and tumor necrosis.

Can kidney cancer recur after surgery?

Recurrence and metastasis are hallmarks of cancer. Kidney cancer commonly relapses in the lungs, typically within 1–3 years post-surgery.

Is adjuvant therapy needed post-surgery?

For Stages I–III, adjuvant therapy lacks conclusive evidence for reducing recurrence or improving survival and is generally not recommended. High-risk cases may warrant exceptions.

How is advanced kidney cancer treated?

For resectable primary tumors with metastases, cytoreductive nephrectomy precedes systemic therapy to enhance efficacy. Non-surgical candidates proceed to first-line treatment.

What is first-line therapy for kidney cancer?

First-line options for recurrent/inoperable cases (predominantly clear-cell carcinoma) include sorafenib, sunitinib, cytokines (e.g., IL-2), or bevacizumab + interferon. Choice depends on patient-specific factors and physician consultation.

What if first-line therapy fails?

Second-line therapies offer limited duration of control. Subsequent options include clinical trials or best supportive care (BSC).

What is best supportive care (BSC)?

BSC prioritizes quality of life over aggressive antitumor treatments when therapies are exhausted. It includes pain management, psychological support, nutrition, and palliative measures.

How does BSC differ from palliative care?

• BSC omits antitumor treatments, focusing solely on symptom relief.
• Palliative care integrates BSC with disease-modifying interventions (e.g., palliative surgery/chemoradiation) across the illness trajectory.
• Late-stage kidney cancer favors BSC over palliative chemo/surgery when targeted therapies fail.

DIET & LIFESTYLE

Is Regular Check-up Necessary After Kidney Cancer Treatment?

After kidney cancer treatment, regular check-ups are still required to detect possible recurrence or metastasis early. Common examinations include symptom inquiry, physical examination, blood tests, biochemistry, chest X-rays, and abdominal + urinary system ultrasounds.

Regarding follow-up frequency: for early-stage kidney cancer, check every 3-6 months in the first 3 years; for intermediate or advanced kidney cancer, check every 3 months in the first 2 years, every 6 months in the 3rd year, and annually thereafter.

PREVENTION

Can Kidney Cancer Be Prevented?

Currently, there is no vaccine, medication, or health supplement that can definitively prevent kidney cancer. Reducing occupational exposure, maintaining a healthy weight, avoiding or quitting smoking, eating a balanced diet, and exercising regularly may lower the risk to some extent, but they cannot guarantee prevention. Even for individuals with a family history of kidney cancer, apart from the above measures and regular check-ups, there are no superior alternatives. Do not believe any folk remedies or health supplements claiming to fully prevent kidney cancer.

Early detection, diagnosis, and treatment are universal keys to overcoming all malignant tumors. Kidney cancer has a relatively low incidence rate. In addition to routine health check-ups, high-risk individuals may consider increasing screening frequency, specifically undergoing kidney ultrasounds, and remaining vigilant. Seek medical attention promptly if suspicious symptoms arise.