People who are obese may be at an increased risk of developing the most common type of kidney cancer, according to a new study.
The most common type is known as clear-cell renal cell cancer (RCC) because when seen under a microscope, the cells that make up this type of cancer appear very pale or clear. It is one of the most lethal types of kidney cancer.
A team of US researchers looked at 1,640 patients with kidney tumours. Of these, 88 percent were found to have malignant tumours, while the remaining 12 percent had benign tumours. Of the malignant tumours, 61 percent were clear cell RCC.
The researchers found that when they factored in the patient's weight, there was a significant association between obesity and clear cell RCC. In fact, obese patients with kidney tumours had a 48 percent increased risk of developing clear cell RCC, compared with patients with a healthy body mass index (less than 30).
Furthermore the odds increased by 4 percent for every extra BMI point.
The study found no such link between obesity and other types of kidney cancer.
"We also looked at other health and lifestyle factors, like diabetes, hypertension and smoking. This showed that the only other factors that were independent predictors of clear cell RCC were male gender and tumour size," said lead author, Dr William Lowrance of the Memorial Sloan-Kettering Cancer Center in New York.
The researchers concluded that BMI is an independent predictor of clear cell RCC and that as BMI increases, the odds of having this type of kidney cancer also increase.
"Although we still need to find out more about the pathology of clear cell RCC, this study is useful as it provides individual predictors of the chance of developing this form of cancer. Of these, obesity provides the strongest association," Lowrance said.
The findings of the study are published in the urology journal, BJUI.