Kidney tumor

Disease Description (Causes and Symptoms)

• Definition: Neoplasm of the kidney refers to a mass (tumor) arising in kidney tissue. It includes both benign lesions (e.g., simple renal cysts and benign renal tumors) and malignant lesions (primarily renal cell carcinoma and metastatic lesions).
• Causes and pathophysiology: Most malignant neoplasms of the kidney are renal cell carcinoma (RCC), which originates in the renal tubules (renal tubular epithelium). Genetic abnormalities (e.g., VHL gene abnormalities), smoking, obesity, hypertension, chronic renal failure, and immunosuppression after organ transplantation are known risk factors. Simple renal cysts often remain benign without atypical changes, but an increase in cyst size and irregularity or calcification of the wall may suggest the possibility of malignancy.
• Main symptoms: Many cases are asymptomatic in the early stages and are often discovered incidentally. When symptoms occur, they may include hematuria (the most common), flank pain (including abdominal distension), a palpable mass, weight loss, fever, generalized weakness, hypertension, and polycythemia (due to ectopic EPO secretion). If metastasis occurs, symptoms involving the lungs, bones, liver, or brain may accompany it.
• Summary of RAG information: Among masses found in the kidneys, the proportion of simple renal cysts is relatively high (approximately 6%–70% of all renal masses, depending on the data), and the detection rate increases with age and differs by sex (e.g., 15% in men in their 50s–60s and 6%–7% in women; 32.2% in men aged 70 or older and 14.6% in women). Simple renal cysts usually have a low likelihood of malignancy and can be managed with observation, but if the findings are unclear, follow-up examinations (e.g., at 3, 6, and 12 months) or CT are recommended.

Treatment Methods

• General principles: Treatment is selected according to the tumor size, location, histological type, presence or absence of metastasis, and the patient's overall condition.
• Localized lesions (small and confined lesions)
  • Active excision: Partial nephrectomy (nephron-sparing surgery) is recommended when possible to preserve renal function. Radical nephrectomy is performed for large tumors or when surrounding structures are involved.
  • Procedural excision: Minimally invasive surgery, such as laparoscopic or robotic surgery, is widely used.
  • Nonsurgical alternatives: Thermal therapy (radiofrequency ablation and cryoablation) may be selected for older adults or patients at high risk from surgery.
  • Active surveillance: For small, slow-growing lesions, particularly in older adults or patients with underlying diseases, surgery may be postponed or avoided through regular imaging follow-up.
• Advanced or metastatic disease
  • Targeted therapy: VEGF pathway inhibitors (e.g., sunitinib, pazopanib, cabozantinib, etc.) and mTOR inhibitors.
  • Immunotherapy: Immune checkpoint inhibitors (e.g., nivolumab alone or in combination with ipilimumab, or pembrolizumab + axitinib combination therapy) are used as first- or second-line treatment.
  • Used as combination therapy with systemic treatment or as monotherapy to relieve symptoms and prolong survival.
  • For localized metastatic lesions, radiation therapy or surgical excision may be considered (for symptomatic lesions).
• Conservative treatment and lifestyle management
  • Renal function monitoring (creatinine and eGFR), blood pressure control, smoking cessation, and weight management.
  • Management of infection, bleeding, and wounds after surgery, as well as rehabilitation and strategies to preserve renal function, are necessary.
• Reflection of the latest guidelines: Because the actual choice of medication and treatment varies according to the stage, histological type, and patient condition, decisions should be made in collaboration with medical oncology, urology, and nephrology specialists, incorporating the latest guidelines and molecular test results.

Precautions (Points to Consider During Treatment)

• Evaluate renal function and overall condition before surgery (cardiopulmonary function, discontinuation of anticoagulants, etc.).
• Targeted therapies and immunotherapies may cause hypertension, proteinuria, liver dysfunction, and immune-related adverse effects, so regular testing and management are necessary.
• Avoid unnecessary invasive treatment for simple renal cysts and manage them with appropriate imaging follow-up.

Complications

• Surgery-related: Bleeding, infection, injury to surrounding organs, and renal failure (especially when function of the opposite kidney is impaired)
• Tumor-related: Dyspnea, bone pain, and neurological symptoms caused by metastasis; tumor lysis; vascular invasion (thrombus); and systemic paraneoplastic syndromes (including fever, anemia, and hyperhidrosis)
• Medication-related: Hypertension, proteinuria, organ toxicity (including liver and heart toxicity), and immune-related adverse reactions

Prognosis

• Early-stage localized tumors can often be cured with surgery. In metastatic disease, treatment can prolong survival, but complete remission is uncommon. Prognosis depends on the stage, histological grade, presence or absence of metastasis, and response to treatment.

Prevention

• Although there is no clear method of primary prevention, management of risk factors (smoking cessation, management of obesity, hypertension, and metabolic syndrome, avoidance of nephrotoxic medications, etc.) is important.
• Screening should be considered for high-risk groups (a significant family history or hereditary syndromes).

Checklist Before an Outpatient Visit (Including Items to Bring and Example Questions)

• Items to bring
  • A list of current medications (including prescription drugs, over-the-counter medications, and dietary supplements)
  • Past medical and surgical history (especially kidney- or genitourinary-related), and family history (kidney cancer and hereditary diseases)
  • Copies of previous blood test and imaging results (ultrasound, CT, and MRI) and radiology reports
  • Symptom record: when symptoms first began, changes in symptoms (hematuria, pain, weight changes, fever, etc.), and the pattern of abdominal distension (when it becomes worse)
  • Lifestyle information: smoking history, alcohol use, and occupational exposure (carcinogens)
• Information that is useful to tell the doctor in advance during the outpatient visit
  • Recent weight changes, changes in urine color (whether hematuria is present), and the exact location and intensity of pain
  • Any anticoagulants or antiplatelet drugs being taken (important if surgery is planned)

Example Questions (Questions to Prepare in Advance for the Doctor)

• "What are the size and characteristics of the suspicious area on the examination results (ultrasound/CT/MRI)?"
• "How do you decide whether this should be followed up, or whether a biopsy or surgery is needed?"

Information on Examinations and Additional Preparation (Examinations Frequently Performed in Outpatient Care)

• Blood tests (CBC, electrolytes, renal function, and liver function)
• Urinalysis (to check for hematuria and proteinuria)
• Renal ultrasound → if necessary, CT of the abdomen and pelvis (contrast-enhanced CT) or MRI
• Tissue diagnosis (core needle biopsy) may be considered when a definitive diagnosis is difficult based on imaging findings.

General Example Questions to Ask the Doctor

• "What additional tests are needed to determine with certainty whether this lesion is benign or malignant?"
• "What are the advantages, disadvantages, and expected side effects of each treatment option (surgery, observation, and nonsurgical procedures)?"
• "How will renal function be managed after treatment? What is the risk of recurrence, and what is the schedule for follow-up tests?"
• "What are the major side effects of standard anticancer drugs or immunotherapy, and how are they managed?"

Examples of Disease-Specific Questions

• "If it is uncertain whether this lesion is a simple renal cyst, what criteria indicate that CT should be performed first instead of follow-up examinations at 3, 6, and 12 months?"
• "When the tumor is less than 3–4 cm, in what situations would you recommend active surveillance rather than partial nephrectomy?"

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Note: Symptoms, examination findings, and treatment plans vary depending on the individual patient's condition. Accurate diagnosis and treatment decisions should be made in consultation with the attending physician.