Renal cell carcinoma
Renal cell carcinoma, the most common type of kidney cancer, accounts for more than 90 percent of all cases. Recently developed surgical treatments and systemic therapies have made significant advances in its treatment. Therapy that targets the vascular endothelial growth factor, a protein that renal cell tumors use for angiogenesis (creating new blood vessels) to nourish their malignant growth, has prolonged life for patients in advanced stages of the disease significantly.
Definition & Facts
Renal cell carcinoma starts small and progressively enlarges over time. It typically grows about one centimeter in diameter per year, usually as a single mass though more than one tumor may be present in a single kidney or both. Patients with multiple tumors may be predisposed genetically.
Formerly, discovery of kidney tumors occurred only after they grew quite large or symptoms of hematuria (blood in the urine), lower back pain or flank pain, or evident abdominal masses developed. Now, fortunately, discovery of most cases comes sooner from ultrasound imaging, computerized axial tomography (CAT) scanning or magnetic resonance imaging (MRI) studies, and from more frequent detection of small, surgically curable lesions.
Renal cell carcinoma is difficult to treat after it metastasizes or spreads beyond the kidney, and cures without recurrence are then rare. Much research on causation now focuses on how genetic mutations affect the cancer's appearance under microscopic examination and indicate its potential for aggressive growth and migration to other areas of the body for metastasis. Physicians hope this information can help them treat kidney tumors in new ways with fewer harmful side effects.
Symptoms & Complaints
- Hematuria, blood in the urine, at first may be visible only under a microscope but if untreated may become quite copious with large blood clots that can obstruct urine flow.
- Pain as an effect of pressure and inflammation from a large kidney tumor radiates from the lower back or side below the rib cage, is steady and constant, and does not diminish as does pain from muscle strain or temporary physical trauma.
- A visible, palpable lump extending outward from the lower abdomen, back, or side may be a sign of a large, long-neglected tumor.
- Chronic fatigue unrelieved by rest or sleep is a common symptom of renal cell carcinoma and of many other cancerous conditions.
The 1964 report of the Surgeon General on smoking and health implicated tobacco smoke clearly as a causative factor in the pathogenesis of renal cell carcinoma. Consensus on the question is by now long complete and beyond challenge by tobacco industry advocates.
The risk that smoking poses for renal cell carcinoma increases dramatically with cigarette numbers consumed per day and decreases substantially as time passes for long-term former smokers. Excessive body mass indices among overweight males and hypertensive blood pressure both increase long-term risks of renal cell cancer. A 1998 study published in the American Journal of Epidemiology rated these three risk factors as identifiable causes in at least 49 percent of renal cell carcinoma cases.
Other modifiable risk factors are exposure to certain environmental toxicants. These exposures include exposure to asbestos; trichloroethylene exposure (an industrial solvent used as a degreaser for metals and a dry-cleaning solvent for fats, oils, and waxes); and thiazide, a diuretic drug for treatment of hypertension. Patients with family histories of renal cancer have a greater chance of developing it.
Diagnosis & Tests
The initial workup takes a detailed medical history, performs a complete physical examination, and in a laboratory does a complete blood cell count, a comprehensive metabolic survey evaluating serum calcium level and liver function, a coagulation profile, and a urinalysis.
Imaging studies should be CT abdominal and pelvic scans with and without contrast dye and chest imaging by either radiographic or CAT scan. Abdominal MRI scanning evaluates tumor extension into the inferior vena cava, the large vein that transports blood from the lower body to the heart.
Such patients often undergo immediate nephrectomy, surgical removal of the affected kidney, as both a diagnostic and a therapeutic measure. Needle biopsy may be useful in patients with small renal masses not requiring full nephrectomy.
Treatment & Therapy
The most important prognostic factor in renal cell carcinoma is the stage that describes the tumor's size and extent of spread within and beyond the kidney.
In Stage I the tumor is entirely within the kidney with no invasion of nearby lymph nodes. Stage II tumors are larger, more than seven centimeters in diameter, but still confined to the kidney.
Stage III includes tumors of any size with or without infiltration into fatty tissue around the kidney, invasion of the large veins from the kidney to the heart, presence in at least one nearby lymph node but not in remote lymph nodes or other organs. Stage IV presents cancers that have spread from the kidney through surrounding tissue and to any distant lymph node or other organs, the lungs, bone, or brain as common examples.
For Stage I tumors less than four centimeters in diameter, excision by partial nephrectomy is the standard treatment. The objective of this procedure is to preserve renal function while removing the tumor. In Stages II and III, radical (full) nephrectomy, which may require partial or total removal of adjacent organs as well, is always necessary.
For Stage IV, cytoreductive (literally reduction in number of malignant cells) nephrectomy before systemic therapy treats patients with surgically removable primary tumors. This is also known as debulking.
Metastasectomy, surgical removal of metastases, secondary cancerous growths that spread from the original site, is a reasonable consideration in cases of solitary metastases or long intervals between initial diagnoses and appearance of metastatic outliers.
Prevention & Prophylaxis
Above all else, tobacco smoking bears major blame for most cases, so desisting from smoking or quitting smoking is an absolutely imperative prophylactic measure. Obesity and hypertension may be lesser threats, but by no means should they be discounted or ignored.
Vigorous and regular exercise and a diet high in fresh fruits and vegetables and low in salt, sugar, and processed foods are also important precautions for maintaining optimal health and decreasing the risk of renall cell carcinoma.