Doctor's Notes on Renal Cell Cancer
Renal cell cancer occurs when the cells of the kidneys start to grow abnormally. Several different types of cancer can develop in the kidney. Clear cell renal cell cancer (renal cell carcinoma), the most common type of kidney cancer in adults, develops in the tubules (part of the filtering system) of the kidney.
There may be no symptoms of renal cell cancer in the early stages. When symptoms of renal cell cancer occur they may include blood in the urine, lower back pain or side pain that will not go away, noticeable lump in the flank, weight loss, fatigue, loss of appetite, fever, night sweats, feeling unwell (malaise), and low red blood cell count (anemia). Symptoms such as a mass that can be felt in the flank, pain in the kidney region, or weight loss are often signs of advanced renal cell cancer.
Renal Cell Cancer Symptoms
In its early stages, renal cell cancer usually causes no noticeable symptoms. Symptoms may occur only when the cancer grows and begins to press on surrounding tissues or spread to other parts of the body. The symptoms vary considerably from person to person. Some people never develop any symptoms before the disease is discovered; the cancer is found when they undergo imaging tests, such as a CT scan, for another reason. In a study in the Journal of Urology, approximately 53% of people with localized renal cell carcinoma had no symptoms.
Signs and symptoms of renal cell cancer may include the following:
- Hematuria (blood in the urine)
- Lower back pain or pain in the flank (side or back above the waist) that will not go away
- Noticeable lump in the flank
- Weight loss
- Fatigue (feeling tired)
- Loss of appetite
- Night sweats
- Malaise (feeling "blah")
- Anemia ("low blood" due to an abnormally low number of red blood cells)
Symptoms such as a mass that can be felt in the flank, pain in the kidney region, or weight loss are usually signs of advanced cancer. The early kidney cancers are usually asymptomatic, and either detected incidentally while testing for some other condition, or because blood found in the urine, which may or may not be visible to the patient.
Other symptoms may result from metastatic renal cell cancer in the bones, lungs, or elsewhere. If the disease attacks the bones, for example, it can cause bone pain, which is deep and achy.
Renal cell cancer can also cause a number of conditions called paraneoplastic syndromes. These are problems caused by the tumor when it releases cytokines (chemicals involved with the immune system) or hormones. Cytokines may or may not cause symptoms, and a person may unknowingly have one or more of the following symptoms.
- High blood pressure
- Hypercalcemia (high level of calcium in the blood)
- Polycythemia ("high blood" due to an abnormally high number of red blood cells)
- Liver disorders
- Muscle weakness
- Neuropathy (numbness, tingling, or burning pain in one or more areas)
- Amyloidosis (abnormal protein deposition in the body)
Renal Cell Cancer Causes
The exact cause of renal cell cancer has not been determined. A number of different factors seem to contribute to renal cell cancer. These risk factors include the following:
- Cigarette smoking doubles the risk of renal cell cancer and contributes to as many as one third of all cases. The more someone smokes, the greater the risk is of that person developing renal cell cancer.
- Obesity is a risk factor. As body weight increases, so does the risk of developing renal cell cancer. This is especially true in women.
- Occupational exposure to petroleum products, heavy metals, solvents, coke-oven emissions, or asbestos
- Cystic kidney disease associated with chronic (long-term) renal insufficiency
- Cystic changes in the kidney and renal dialysis
- Tuberous sclerosis
- Von Hippel-Lindau (VHL) disease, an inherited disease associated with several cancers
- Hereditary renal cancer
- Associated malignancy such as lymphoma
In the most basic terms, cancer refers to cells that grow out-of-control and invade other tissues. Cells may become cancerous due to the accumulation of defects, or mutations, in their DNA. Certain inherited genetic defects (for example, BRCA1 and BRCA2 mutations) and infections can increase the risk of cancer. Environmental factors (for example, air pollution) and poor lifestyle choices—such as smoking and heavy alcohol use—can also damage DNA and lead to cancer.
Most of the time, cells are able to detect and repair DNA damage. If a cell is severely damaged and cannot repair itself, it usually undergoes so-called programmed cell death or apoptosis. Cancer occurs when damaged cells grow, divide, and spread abnormally instead of self-destructing as they should.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.