Kidney cancer also called renal cancer is a disease in which kidney cells become malignant (cancerous) and grow out of control, forming a tumor. Almost all kidney cancers first appear in the lining of tiny tubes (tubules) in the kidney. This type of kidney cancer is called renal cell carcinoma.
The two most common types of kidney cancer are renal cell carcinoma (RCC) and transitional cell carcinoma (TCC), also known as urothelial cell carcinoma of the renal pelvis. The most common kidney cancer in adults is renal cell carcinoma. It forms in the lining of very small tubes in the kidney. Cancers found in the center of the kidney are known as transitional cell carcinoma.
Renal cell carcinoma: Renal cell carcinoma (RCC) is a kidney cancer that originates in the lining of the proximal convoluted tubule, a part of the very small tubes in the kidney that transport primary urine. RCC is the most common type of kidney cancer in adults.
Transitional cell carcinoma: It is also called urothelial carcinoma, which is a type of cancer that typically occurs in the urinary system. It is the most common type of bladder cancer and cancer of the ureter, urethra, and urachus. Transitional cell carcinomas arise from the transitional epithelium, a tissue lining the inner surface of these hollow organs.
Symptoms of kidney cancer
In many cases, people may have no early symptoms of kidney cancer. As the tumor grows larger, symptoms may appear. You may have one or more Kidney cancer symptoms. Some possible signs and symptoms of kidney cancer include:
[i] Blood in the urine (hematuria).
[ii] A reduced amount of urine.
[iii] Weight loss that occurs for no known reason.
[iv] Feet from the retention of fluids caused by the failure of your kidneys to eliminate water waste.
[v] Extreme fatigue.
[vi] A high temperature and heavy sweating.
[vii] Loss of appetite.
[viii] A lump in your side or abdomen.
[ix] Persistent pain in the abdomen.
[x] Fever that lasts for weeks and isn’t caused by a cold or other infection.
[xi] Unexplained shortness of breath.
Causes of kidney cancer
Scientists have found several risk factors that may cause you more likely to develop kidney cancer. Factors that increase the risk of kidney cancer include:
Smoking may increase the risk of developing renal cell carcinoma (RCC). The risk drops if you stop smoking, but it takes many years to get to the risk level of someone who never smoked.
Exposure to certain substances
Exposure to certain substances increases the risk of RCC. Some of these substances are cadmium (a type of metal), some herbicides, and organic solvents, particularly trichloroethylene.
Obesity is a medical condition in which excess body fat has accumulated to the extent that it may have a higher risk of developing RCC. Obesity may cause changes in certain hormones that can lead to RCC.
High blood pressure
The risk of kidney cancer is more in people with high blood pressure. Certain medicines used to treat high blood pressure may raise the risk of kidney cancer, but it may be the condition or the medicine (or both) that may be the cause of the increased risk.
Phenacetin: This drug used to be a popular non-prescription pain reliever and has been linked to RCC in the past. But it has not been available for over many years, so it no longer appears to be a major risk factor of kidney cancer.
Diuretics: Diuretics (water pills) may be linked to a small increase in the risk of RCC. It is not clear whether the cause is drugs or high blood pressure.
A family history of kidney cancer
People with a family history of kidney cancer or renal cell cancer (without one of the known inherited conditions listed below) have a higher chance of developing this cancer. It’s not clear whether this is due to shared genes or something that both people were exposed to in the environment, or both.
There are also other possible risk factors such as
Having kidney disease that needs dialysis, being infected with hepatitis C, kidney stones, regular use of NSAIDs (Nonsteroidal anti-inflammatory drugs) such as ibuprofen and naproxen, and previous treatment for testicular cancer or cervical cancer.
Diagnosis of kidney cancer
The tests and procedures used to diagnose kidney cancer include:
Blood and urine tests
Tests of your blood and your urine may give your doctor clues about what’s causing your signs and symptoms.
Blood chemistry tests: These tests are usually done in people who might have kidney cancer because cancer can affect the levels of certain chemicals in the blood. For example, high levels of liver enzymes are sometimes found. High blood calcium levels may indicate that cancer has spread to the bones, and may, therefore, prompt a doctor to order a bone scan. Blood chemistry tests also look at kidney function, which is especially important if certain imaging tests or if surgery is planned.
Complete blood count (CBC): This is a test that measures the amounts of different components in the blood, such as RBC, WBC, Platelets, etc. This test result is often abnormal in people with renal cell cancer. Anemia (having too few red blood cells) is very common. Blood counts are also important to make sure a person is healthy enough for surgery.
Urine testing: In this testing, microscopic and chemical tests are done on a urine sample to look for small amounts of blood and other substances not seen with the naked eye. Most of the patients with renal cell cancer will have blood in their urine.
Imaging tests use x-rays, magnetic fields, sound waves, or radioactive substances to create pictures of the inside of your body. Imaging tests allow your doctor to visualize a kidney tumor or abnormality. Unlike most other cancers, doctors can often diagnose kidney cancer with fair certainty based on imaging tests without doing a biopsy (removing a sample of the tumor to be looked at under a microscope). In some patients, however, a biopsy may be needed.
Biopsies are not often used to diagnose kidney tumors. Imaging tests usually provide enough information for a surgeon to decide if an operation is needed. A biopsy is sometimes done to get a small sample of tissue from an area that may be cancer when the imaging tests are not clear enough to permit surgery.
The biopsy may also be done to confirm cancer if a person might not be treated with surgery, such as with small tumors that will be watched and not treated, or when other treatments are being considered.
Treatment of kidney cancer
The kidney cancer treatment may depend on a number of factors, including your general health, the kind of kidney cancer you have, whether cancer has spread and your preferences for treatment.
Surgery: It is the main treatment for the majority of kidney cancers, with the goal of removing the tumor and preserving normal kidney function. Surgical procedures used to treat kidney cancer may include:
Nephrectomy (Removing the affected kidney): A complete (radical) nephrectomy involves removing the entire kidney, a border of healthy tissue and occasionally additional nearby tissues such as the lymph nodes, adrenal gland or other structures.
Partial nephrectomy (Removing the tumor from the kidney): It also called kidney-sparing or nephron-sparing surgery, the surgeon removes the tumor and a small margin of healthy tissue that surrounds it rather than the entire kidney. It can be done as an open procedure, or laparoscopically or with robotic assistance.
Types of kidney cancer
Renal cell carcinoma and renal pelvis carcinoma, other, less common types of kidney cancer include:
(i) Juxtaglomerular cell tumor (reninoma): It is an extremely rare kidney tumor of the juxtaglomerular cells, with less than 100 cases reported in the literature. This tumor typically secretes renin, hence the former name of reninoma.
(ii) Angiomyolipoma: Angiomyolipomas are the most common benign tumor of the kidney. Although regarded as benign, angiomyolipomas may grow such that kidney function is impaired or the blood vessels may dilate and burst, leading to bleeding.
(iii) Bellini duct carcinoma: Collecting duct carcinoma (CDC) (also known as Bellini duct carcinoma, is a type of kidney cancer that originates in the papillary duct of the kidney.
(iv) Clear-cell sarcoma of the kidney: Clear cell sarcoma of the kidney (CCSK) is an extremely rare type of kidney cancer. Clear cell sarcoma of the kidney can spread from the kidney to other organs, most commonly the bone, but also including the lungs, brain, and soft tissues of the body.
(v) Mesoblastic nephroma: Congenital mesoblastic nephroma, while rare, is the most common kidney neoplasm diagnosed in the first three months of life. This neoplasm is generally non-aggressive and amenable to surgical removal.
(v) Wilms’s tumor: Wilms’s tumor, also known as nephroblastoma, is a cancer of the kidneys that typically occurs in children, rarely in adults.
(vi) Mixed epithelial-stromal tumor: A cystic nephroma, also known as multilocular cystic nephroma, mixed epithelial-stromal tumor (MEST) and renal epithelial-stromal tumor (REST), is a type of rare benign kidney tumor.