Kidney cancer

Signs and Symptoms

Early-stage kidney cancer typically does not present symptoms, making it undetectable during physical examinations. As the disease progresses, symptoms may emerge, including blood in the urine, a lump in the abdomen, and back or flank pain. Other advanced symptoms can include weight loss, fever, night sweats, palpable swollen lymph nodes, bone pain, persistent cough, and swelling in the lower legs.

Paraneoplastic syndromes, caused by substances produced by cancer cells, can manifest as endocrine or non-endocrine dysfunctions. Endocrine issues may involve hypercalcaemia, hypertension, polycythaemia, liver dysfunction, galactorrhea, and Cushing's syndrome. Non-endocrine dysfunctions may include amyloidosis, anaemia, neuromyopathies, vasculopathy, and coagulopathy.

Causes

Several risk factors contribute to the development of kidney cancer, such as smoking, high blood pressure, obesity, a family history of kidney cancer, hepatitis C infection, and previous treatments for testicular or cervical cancer. Approximately 25-30% of kidney cancer cases are attributed to smoking, with a dose-dependent risk increase. Smoking cessation significantly reduces this risk.

Diagnosis

Kidney cancer is often incidentally discovered through ultrasound and CT imaging performed for unrelated abdominal complaints. Medical imaging, including ultrasonography, CT scans with contrast, and MRI, plays a very important role in characterising kidney masses to determine whether they are benign or malignant.

Histopathologic Classification

The main types of kidney cancer include RCC, TCC of the renal pelvis, and Wilms' tumour, among others. RCC originates from the proximal convoluted tubule of the nephron, while TCC arises from the transitional cells lining the renal pelvis. Other rare types include sarcomas, metastatic tumours, lymphomas, and carcinoid tumours.

Immunohistochemistry

Immunohistochemistry helps in differentiating various kidney cancer types based on specific markers like PAX8, CD10, CAIX, RCC, melanocytic markers, vimentin, CK7, and others.

Laboratory Studies and Biopsy

Blood tests, including a comprehensive metabolic panel (CMP) and complete blood count (CBC), along with urinalysis, are essential in evaluating kidney function and overall health. Renal mass biopsy (RMB) can confirm malignancy and guide therapy, especially for masses likely to be hematologic, metastatic, inflammatory, or infectious.

Staging

Staging involves determining the extent and spread of the disease using the TNM classification system. This system assesses the primary tumour (T), lymph nodes (N), and distant metastasis (M). Images illustrating the stages of kidney cancer help in understanding disease progression.

Treatment

Treatment for kidney cancer depends on the type and stage of the disease. Surgery is the primary treatment, as kidney cancer often does not respond well to chemotherapy and radiotherapy. Surgical options include partial or total nephrectomy, with the latter typically reserved for more advanced cases. Other treatments may involve freezing the tumour or using high temperatures, although these are not standard.

Biological therapies such as everolimus, torisel, nexavar, sutent, and axitinib, along with immunotherapy using interferon and interleukin-2, are also employed. Sunitinib and pazopanib are the current standards of care in the adjuvant setting, followed by everolimus, axitinib, and sorafenib. Immune checkpoint inhibitors like nivolumab and cabozantinib have shown promise in advanced stages.

For Wilms' tumour in children, a combination of chemotherapy, radiotherapy, and surgery is the standard treatment.

Epidemiology

Globally, around 403,300 new cases of kidney cancer were diagnosed in 2018, with 175,000 resultant deaths. The highest rates are recorded in North America, with the lowest in Asia and Africa. Lifestyle factors like smoking, obesity, and hypertension significantly contribute to the risk. The incidence of kidney cancer increases with age, peaking around 75 years. Men are twice as likely to develop kidney cancer compared to women. Incidence rates also vary internationally, with the highest rates in Czech Republic and Lithuania and the lowest in China, Thailand, and African countries. Screening accessibility and healthcare disparities play a significant role in these variations.

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Self-assessment MCQs (single best answer)

Which type of kidney cancer accounts for approximately 80% of cases?

Which of the following is NOT a common symptom of advanced kidney cancer?

Which paraneoplastic syndrome is associated with kidney cancer?

What is a significant risk factor for developing kidney cancer?

Which imaging technique is NOT typically used to diagnose kidney cancer?

In the TNM classification system for staging kidney cancer, what does the 'N' represent?

What is the primary treatment for kidney cancer?

Which of the following is an immunotherapy used in the treatment of advanced kidney cancer?

Which country has the highest incidence of kidney cancer?

What is the peak age for the incidence of kidney cancer?