A Closer Look at the Obesity and Kidney Cancer Connection

Health Writer

It’s become common knowledge that obesity can put you at risk for all sorts of health problems. To start, it can lead to developing Type 2 diabetes, cardiovascular disease, arthritis, fibromyalgia and sleep disorders. Obesity is also linked to several cancers including certain types of breast cancer, colon cancer and prostate cancer. And now, a new study suggests that obesity may raise the risk of recurrent renal cell carcinoma.

Understanding renal cell carcinoma** Renal cell carcinoma** is a type of cancer that typically starts in the kidney and most often occurs in men between the ages of 50 to 70. While it’s not certain what causes this type cancer, the risk factors include:

  • Being on long-term dialysis
  • A family history of the disease
  • High blood pressure
  • Having a horseshoe-shaped kidney
  • Smoking
  • Having Von Hippel, a hereditary disease
  • Obesity

Treatment options include surgically removing part or all of the kidney and, in some cases, hormone therapy. Chemotherapy and radiation are usually not effective.

The obesity link

Obviously, one of the biggest fears a cancer patient faces is a possible recurrence and poor prognosis. This new study suggests that having obesity can raise the risk of recurrence of this type of kidney cancer and a poorer prognosis or outcome.

However, in order to understand the study, it’s important to first understand leptin, and the way it regulates energy balance in the body. The hormone does this by suppressing food intake and helping to induce weight loss. Obese patients are often found to have leptin-resistance, which explains why they may struggle with feeling full, and why they seem to gain weight.

And in the case of renal cell carcinoma tumors, it appears that obesity may also cause leptin receptors, called LEPRs, to become hyper-methylated or, in other words, over-express certain genes. This mechanism, methylation, plays a major role in silencing tumor suppression cells or in the over-expression of cancer gene activity in cancer cells.** Examining the research**

The study involved 240 newly diagnosed RCC patients who had not yet received any cancer treatments. The average age of the subjects was 59, and all were non-smokers. Most of the subjects had clear cell RCC and were in early stages of the disease. Researchers wanted to look at the association between methylation activity of twenty obesity-related genes and RCC recurrence and prognosis.

Subjects were classified into high or low LEPR methylation groups. Those in the high LEPR methylation group were found to be at a significantly higher risk of having a RCC tumor recurrence. High LEPR methylation also seemed to indicate, “more advanced tumor features,” which includes a highly pathologic stage of disease and a high grade of disease.

And even when researchers adjusted for age, gender, pathology staging of the disease, grade of the cancer, smoking status, BMI, history of hypertension and histology of the tumor, they found that having a diagnosis of obesity was associated with a higher rate of recurrence of the RCC tumor and a poorer prognosis. The researchers concluded that more studies would be necessary to further understand the connection between obesity, LEPR methylation and RCC recurrence.

An expert weighs in

Nikhil Durandhar, a professor and the chair of Nutritional Sciences at Texas Tech University, and former president of The Obesity Society had this to say about the study:

"This study shows an association. Not a causation between obesity and renal cancer. For instance, tumors require extra blood supply for growing. leptin is thought to promote angiogenesis ( growth of blood vessels) - a tumor may recruit leptin to get the additional blood supply needed for tumor growth. In that case, leptin's role will be in tumor growth and not necessarily in tumor formation (leptin levels are high in people with obesity). Nonetheless, obesity and cancer connection is well known. As done in this study, it is important to recognize the molecular players involved in this link, to develop effective treatment or prevention approaches."

RecommendationsIf anything, these latest findings add to the abundance of evidence that suggest it’s crucial to find a path to** sustained** weight loss. The data has shown that even small weight loss efforts can lead to noticeable benefits, so it’s important to follow a diet that is safe and effective. Some strategies for slow, steady weight loss include:

  • Having a daily exercise program
  • Limiting processed foods to cut back on unhealthy fats, sodium and sugar
  • Including a serving of lean protein at every meal for satiety
  • Making fruits and vegetables the foundation of your diet
  • Choosing whole grains, fat free dairy and other whole foods as mainstays of your diet
  • Eating more frequently at home and cooking the meals yourself to have control over the ingredients and portion sizes
  • Staying hydrated, mostly with water, unsweetened teas and coffee

Furthermore, new research suggests that improving gut microbe balance can help some individuals to lose weight - so adding a little yogurt can’t hurt.




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