Kidney cancer, also known as renal cancer, is currently ranked the 14th most common cancer worldwide and in India, as per Globocan 2020 survey, it ranked 21 with 16861 new cases every year. Kidney cancer tends to occur most commonly in individuals over the age of 40 and is more common in males.
Most of them occur spontaneously and very few are associated with hereditary conditions. Predisposing hereditary conditions include von Hippel-Lindau disease and hereditary papillary renal cell carcinoma. Potential risk factors are cigarette smoking, obesity and high blood pressure.
Although most of the lesions are malignant unless proved otherwise, but about 20 per cent to 25 per cent of kidney tumours are benign. The most common types of benign lesions are oncocytoma and angiomyolipoma. Renal cell carcinoma (RCC) is the most common type of kidney cancer and clear cell RCC being the most common subtype and represents greater than 80 per cent of renal cell carcinomas.
Approximately 60 per cent of kidney cancers are diagnosed at a stage when it is confined to the kidney without evidence of spread. Localised cancers may be detected incidentally without any symptoms or may be associated with a classical triad of symptoms which include hematuria (blood in the urine), flank pain or palpable lump. Approximately 40 per cent of kidney cancers are diagnosed at an advanced stage characterised by spread to regional lymph nodes, distant metastasis or involvement of surrounding structures. These tumours carry a higher risk of recurrence following treatment.
The overall five-year survival for patients with localized cancer is around 90 per cent, between 20 per cent to 30 per cent of patients with localised kidney cancers develop recurrent disease. Surgery being the most effective treatment, although in special circumstances (very small tumours or in patients unfit for surgery) ablative techniques are available. The overall five-year survival for advanced kidney cancer is approximately 60 per cent but reduces to 10 per cent for distant metastatic disease. As chemo and radiation therapy are ineffective against kidney cancer, surgery still holds an important role in the management of advanced kidney cancer and can be offered in the setting of metastatic disease.
Clinical assessment is done with examination and imaging in form of CT scan of the abdomen and thorax. In cases of advanced cases, additional test such as MRI and Bone Scan may be necessary. PET CT scan is of limited role or value in staging workup of kidney cancers.
Treatment for localised kidney cancer includes active surveillance, Ablative Therapy (radiofrequency or cryosurgery), Nephrectomy (Partial or Radical Total). Ablative Therapy is most commonly used for lesions less than 3 cm or in patients who are unfit for surgery. In general, active surveillance may be appropriate in older individuals with small (>= 3 cm) kidney tumours and in patients who are again unfit for surgery. Findings such as an increase in the size of the lesion or alteration in morphology may warrant a decision regarding initiation of active treatment.
Partial Nephrectomy is often recommended for smaller lesions, single kidney or tumours in the bilateral kidney, or settings of impaired renal function. Partial nephrectomy can be performed either laparoscopically or with open surgery.
Radical nephrectomy is the standard of care or gold standard treatment for high-risk kidney cancers. For more advanced lesions lymph node dissection, tumour thrombus removal or removal of affected organs may be required. Total nephrectomy may also be recommended in the setting of metastatic disease followed by targeted therapy.
Locally advanced and metastatic cancer presents treatment challenges because renal cell carcinoma is not responsive to radiation or chemotherapy. As stated earlier, surgery may play a role, in cases of regional lymph node metastases or solitary distant metastases. In such cases, total nephrectomy can be combined with mastectomy.
Systemic Therapy or Targeted therapy
As stated earlier conventional chemotherapy is of limited value in the management of renal cancers however Immunotherapy using interferon and interleukin-2 has been used in metastatic settings with approximately 15 per cent of patients have a partial response, and between 3 to 5 per cent have a complete response. Newer targeted agents such as tyrosine kinase inhibitors are being used to treat high-risk and metastatic kidney cancer.