Kidney Cancer Causes, Diagnosis, Symptoms, and Treatment on MedicineNet.com

Font Size

Kidney Cancer

Weight Gain & Cancer Risk

Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

Could weight gain increase your risk for kidney cancer? Excess weight is a known risk factor for many chronic diseases, such as diabetes and heart disease. Obesity has also been linked an increased risk for developing some cancers. To clarify the effects of weight gain on cancer risk, researchers in 2007 conducted an analysis of many studies reported in medical journals that describe 282,137 cases of cancer. The researchers wanted to see if weight gain had an effect on the risk for certain cancer types.

In particular, the researchers looked at the risk of cancer associated with a weight gain corresponding to an increase of 5 kg/m² in body mass index (BMI). In terms of actual pounds gained, a man with a normal-range BMI of 23 would need to gain 15 kg (33 lbs.) of weight, while a woman with a BMI of 23 would need to gain 13 kg (28.6 lbs.) to correspond to an increase of 5 in the BMI.

The results, published in the Lancet in February 2008, revealed that weight gain is positively associated with the risk of developing a variety of types of cancer as described below.

For women, a weight gain corresponding to an increase of 5 in the BMI resulted in a significant increase in risk for developing four cancer types:

esophageal adenocarcinoma (double the risk),

endometrial cancer (slightly more than double the risk),

gallbladder cancer (slightly more than double the risk), and

kidney (renal) cancer.

Learn how weight gain increases one's risk for other forms of cancer »

Top Searched Kidney Cancer Terms

symptoms, causes, treatment, prognosis, hematuria, diagnosis, is kidney cancer hereditary?

The kidneys

The kidneys are a pair of organs on either side of the spine in the lower abdomen. Each kidney is about the size of a fist. Attached to the top of each kidney is an adrenal gland. A mass of fatty tissue and an outer layer of fibrous tissue (Gerota's fascia) enclose the kidneys and adrenal glands.

The kidneys are part of the urinary tract. They make urine by removing wastes and extra water from the blood. Urine collects in a hollow space (renal pelvis) in the middle of each kidney. It passes from the renal pelvis into the bladder through a tube called a ureter. Urine leaves the body through another tube (the urethra).

The kidneys also make substances that help control blood pressure and the production of red blood cells.

Understanding cancer

Cancer begins in cells, the building blocks that make up tissues. Tissues make up the organs of the body.

Normally, cells grow and divide to form new cells as the body needs them. When cells grow old, they die, and new cells take their place.

Sometimes this orderly process goes wrong. New cells form when the body does not need them, and old cells do not die when they should. These extra cells can form a mass of tissue called a growth or tumor.

Tumors can be benign or malignant:

Benign tumors are not cancer:
- Benign tumors are rarely life threatening.
- Usually, benign tumors can be removed, and they seldom grow back.
- Cells from benign tumors do not invade tissues around them or spread to other parts of the body.
Malignant tumors are cancer:
- Malignant tumors are generally more serious than benign tumors. They may be life threatening.
- Malignant tumors often can be removed, but they can grow back.
- Cells from malignant tumors can invade and damage nearby tissues and organs. Also, cancer cells can break away from a malignant tumor and enter the bloodstream or lymphatic system. That is how cancer cells spread from the original cancer (primary tumor) to form new tumors in other organs. The spread of cancer is called metastasis.

Several types of cancer can start in the kidney. This booklet is about renal cell cancer, the most common type of kidney cancer in adults. This type is sometimes called renal adenocarcinoma or hypernephroma. Another type of cancer, transitional cell carcinoma, affects the renal pelvis. It is similar to bladder cancer and is often treated like bladder cancer. Wilms tumor is the most common type of childhood kidney cancer. It is different from adult kidney cancer and requires different treatment. Information about transitional cell carcinoma and Wilms tumor is available from the Cancer Information Service at 1-800-4-CANCER and at http://cancer.gov.

When kidney cancer spreads outside the kidney, cancer cells are often found in nearby lymph nodes. Kidney cancer also may spread to the lungs, bones, or liver. And it may spread from one kidney to the other.

When cancer spreads (metastasizes) from its original place to another part of the body, the new tumor has the same kind of abnormal cells and the same name as the primary tumor. For example, if kidney cancer spreads to the lungs, the cancer cells in the lungs are actually kidney cancer cells. The disease is metastatic kidney cancer, not lung cancer. It is treated as kidney cancer, not lung cancer. Doctors sometimes call the new tumor metastatic or "distant" disease.