Kidney Cancer begins when healthy cells in one or both kidneys change and grow uncontrollably, forming a mass called a tumor. A tumor can be malignant, indolent, or benign. A malignant tumor is cancerous, meaning it can grow and spread to other parts of the body. An indolent tumor is also cancerous, but this type of tumor rarely spreads to other parts of the body. A benign tumor means the tumor can grow but will not spread.

Often, kidney cancer is found when a person has an x-ray or ultrasound (see the Diagnosis section) for another reason. In its earliest stages, kidney cancer causes no pain. Therefore, symptoms of the disease usually appear when the tumor is large and begins to affect nearby organs.

People with kidney cancer may experience the following symptoms or signs. Sometimes, people with kidney cancer do not show any of these symptoms. Or, these symptoms may be caused by a medical condition that is not cancer.          

Blood in the urine
Pain or pressure in the side or back
A mass or lump in the side or back
Swelling of the ankles and legs
High blood pressure
Anemia, which is a low red blood cell count
Fatigue
Loss of appetite
Unexplained weight loss
Recurrent fever that is not from cold, flu, or other infection
For men, a rapid development of a cluster of enlarged veins, known as a varicocele, around a testicle

Kidney Cancer Diet and Nutrition
People receiving treatment for kidney cancer need proper nutrition to help their bodies remain strong. Chemotherapy, radiation therapy, and other treatments take a huge toll on the body, and a healthy, planned cancer diet gives it the fuel to combat the side effects from these therapies.

Unfortunately, these therapies also create unique challenges when it comes to eating a healthy diet. Patients often lose their appetites completely, or find their tastes have changed to the point where it's hard to eat anything. They are also more vulnerable to infection, which means their food needs to be carefully prepared to prevent further illness.

What You Should Eat
A kidney cancer diet should include many of the things found in any healthy diet, with some nutritional tweaks to combat the specific effects of cancer treatment. A patient's daily nutrition should include:

Plenty of fruits and vegetables. "You want to choose lots of plant source products, so make sure you eat 5 to 10 servings of fruits and veggies a day," says Dee Sandquist, RD, spokeswoman for the American Dietetic Association.
A good amount of whole grains. "Whole grains are a great source of B vitamins and iron and fiber," Sandquist says. These include whole wheat, brown rice, oatmeal, and cracked wheat.

Lots of calories. Here's where a cancer diet differs from a normal diet. Nutritionists recommend that people eat high-calorie foods to help keep the body from shedding pounds as a result of treatment. "The main thing during treatment is to really maintain weight," Sandquist says. Cancer patients are often urged to eat high-calorie, high-protein foods such as peanut butter, milkshakes, sauces, gravies, meats, cheeses, and whole milk.

The right amount of protein. Kidney function may decrease as a result of cancer treatment, particularly if surgeons have to remove one kidney. High-protein diets may cause the kidneys to work harder to remove urea, a waste product created as your body breaks protein down for use. Kidney cancer patients need to keep their weight up, but should discuss their protein intake with medical experts. "How much protein a kidney cancer patient should eat would depend on their kidney function," Sandquist says. "The physician and registered dietitian would work with the patient and adjust the diet accordingly."