Renal cancer is also called kidney cancer. Renal cancers originate from cells lining the proximal tubules of the kidney. Kidneys are made up of numerous nephrons, which are the microscopic structural and functional unit of the kidneys. Proximal tubule is the part of these nephrons which plays an important role in kidney function of absorption of glucose, amino acids and other solutes from blood and ultimately helps in forming urine to remove toxins from our body.
Renal cancer or kidney cancer is cancer arising in the kidneys. Kidneys are two reddish-brown bean-shaped organs about the size of the fist located posteriorly on either side of the spine, just below the ribcage. Their function is to filter blood to remove impurities, excess minerals and salts and extra water. Kidneys also produce hormones that control blood pressure and affect red blood cell production.
Although most of the people have two functioning kidneys, still both function independently. Thus, if one kidney has become dysfunctional or has been removed (for any reason), that person can still survive with a single normal functioning kidney.
Various risk factors that can increase the chances of one being affected by renal cancer are:
- Smoking: Smoking has been shown to increase risk of renal cancer. Large studies have shown about 38 to 40% increased risk of renal cancer in current and formal-smokers.
- Obesity: Obese individuals are more at risk of developing renal cancer.
- Hypertension: Hypertensive individuals are at an increased risk of getting renal cancer.
- Prolonged use of pain medications: Prolonged use of medications to reduce pain (analgesics), can also increase one’s the risk of getting renal cancer.
- Long term dialysis: Need for long term dialysis in patients with chronic renal failure, has also been shown to increase the risk of getting renal cancer.
- Genetic conditions: Inherited syndromes such as von Hippel-Lindau disease, Birt-Hogg-Dube syndrome, Tuberous sclerosis complex, Hereditary papillary renal cell carcinoma or Familial renal cancer. increases one’s risk of getting renal cancer.
- Family history: A positive family history of renal cancer in the first degree relative, has been associated with increased risk of acquiring renal cancer.
The various types of renal cancers are:
- Renal cell carcinoma: Renal cell carcinoma (RCC) is the most common type of kidney cancer affecting adults, making up for 85 to 90% of all renal cancers. The major histological variants include clear cell carcinoma, papillary renal carcinoma types 1 & 2, chromophobe carcinoma and collecting duct carcinoma.
- Urothelial carcinoma: This is also called transitional cell carcinoma and accounts for only 5% of cases of all renal cancers. Transitional cells are present in the renal pelvis, which functions as a funnel for urine flowing to the ureter and then into the urinary bladder. Urothelial or transitional cell carcinomas, hence begin in this renal pelvis.
- Sarcoma: Renal sarcomas are rare and account for only 1-2 % of all renal cancers. Fibrosarcomas are the most common type and have a poor prognosis due to late diagnosis. Other types of renal sarcomas include rhabdomyosarcoma, leiomyosarcoma, liposarcoma, osteogenic sarcoma etc.
- Wilms tumour: Wilms tumor or nephroblastoma is the most common renal cancer affecting children. It usually affects children aged 3-4 years. With the current available multi-modality treatment, children of Wilms tumor experience excellent survival.
Symptoms of renal cancer include:
- Hematuria or blood in urine
- Flank or back pain
- Lump in abdomen or flank region
- Advanced disease can present with non-reducing varicocele, lower limb swelling, loss of weight, bony pains, neck lymph nodes etc.
The symptoms can appear in different forms as mentioned above and hence, if you are experiencing a combination of any of these symptoms, especially over longer periods, you should consult a doctor.
Once, you see a specialist, the following tests may be carried out:
- A physical exam: A through physical examination will be carried out, after taking a detailed history of your symptoms
- Ultrasound: An abdominal ultrasound is usually the first test done to see if any suspicious renal masses are present.
- CT scan: A CT scan of the chest, abdomen and pelvis is done to determine the stage of disease; which in turn will help decide the best treatment sequence for a given patient.
- MRI scan: An MRI scan may sometimes be asked for, especially in early cases of suspicious renal masses.
- PET CECT scan: A PET CT scan may be suggested in advanced or recurrent cases to rule out spread of cancer to other sites, eg lungs, liver, bone, etc.
- Image guided biopsy: In patients with metastatic renal cancer, an ultrasound or CT scan may be used as a guide to perform biopsy from the renal mass, so as to confirm the histopathological type to decide further treatment. In patients with enlarged lymph nodes in the neck (due to spread from renal cancer), a neck lymph node biopsy may be performed instead, for the same purpose.
- Urine cytology: A urine cytology is usually performed in cases of transitional cell carcinoma of the kidneys along with evaluation of the entire urinary tract to rule synchronous tumors in other parts of the urinary tract like urinary bladder or ureters.
The treatment for renal cancer depends upon the stage of cancer, patient’s health and medical conditions, patient’s nutritional status etc. The different treatment includes:
- Surgery: Surgical procedures to remove renal cancer are:
- Radical Nephrectomy: In large tumors involving most of the kidney or central part of the kidney, a radical nephrectomy is performed. This procedure involves removal of the entire kidney along with the surrounding fatty tissue and most often the ipsilateral adrenal gland. A radical lymph nodal dissection is usually performed simultaneously to remove all the draining lymph nodes in the surrounding region.
- Partial Nephrectomy or Nephron sparing surgery: In patients with smaller tumors, usually located towards upper or lower parts of the kidney, a partial nephrectomy is preferred. The goal of this procedure, is to remove the entire tumor with a margin of normal tissue while preserving the as much normal kidney as possible.
- Cytoreductive Nephrectomy: A nephrectomy is usually not performed in patients with stage IV renal cancer. However, nephrectomy may be required in certain special situations of in patients with stage IV (metastatic) renal cancer, wherein the affected kidney is removed (cytoreductive nephrectomy), for the following reasons; the renal tumor is forming the main tumor bulk or the patient is experiencing significant pain and persistent hematuria, not improving with conservative treatments.
- Targeted therapy: Targeted therapy uses drugs to target specific proteins within the cancer cells, to kill them. Targeted therapy drugs used in renal cancer include; tyrosine kinase inhibitors like Sunitinib, Sorafenib, Pazopanib, Cabozantinib, Lenvatinib or VEGF protein inhibitor like Bevacizumab. Targeted therapy is recommended in metastatic renal cancer or in patients with locally advanced renal cancer as neoadjuvant treatment (to reduce the size of tumor prior to surgery) or in patients after surgery, as adjuvant treatment.
- Immunotherapy: In advanced cases, biological therapy or immunotherapy may be suggested for treatment. Immunotherapy targets the cells, which affect the body’s immune response and helps the body in killing cancer cells.
- Radiation therapy: Radiation therapy is recommended in patients with stage IV renal cancer to treat painful bony metastasis.
Preventive measures to reduce the risk of getting renal cancer are:
- Avoid smoking and exposure to tobacco products
- Maintain a healthy weight by regular exercises and proper diet.
- Regular health check-up to ensure your blood pressure in under control. Follow instructions given by your treating doctor like taking timely medications, salt-restricted diet, exercise schedule, etc to maintain normal blood pressure.
- Avoid excessive use of pain medications, without proper medical consultations.
- Patients on long-term dialysis or those with inherited genetic syndromes with risk of getting renal cancer, should undergo regular screening with their treating doctors, so as to detect renal cancers in early stages, thus ensuring excellent outcome.