Obesity linked to kidney cancer

On January 22, 2010, in Uncategorized, by Andrea

Not a good day.

From Medscape:

Obesity Linked to Clear-Cell Renal Cell Carcinoma

Laurie Barclay, MD

January 22, 2010 — Obesity is associated with an increased risk for clear-cell renal cell carcinoma (RCC), according to the results of a case series reported in the January issue of BJU International.

“Recent scientific breakthroughs about what causes clear-cell RCC have led to the development of new targeted therapies,” lead author William T. Lowrance, from Memorial Sloan-Kettering Cancer Center (MSKCC), New York, NY, said in a news release. “This makes it more important than ever to identify those people who face an increased risk of developing this variant, which is on the rise in the USA.”

The goal of the study was to evaluate the association between body mass index (BMI) and histologic features of RCC in a contemporary cohort of 1640 patients with renal cortical tumors being surgically removed at MSKCC from January 2000 to December 2007. Of these tumors, 12% were benign and 88% were malignant; of these, 61% were clear-cell RCCs.

The association of BMI with RCC histologic features was examined with multivariable logistic regression.

“The widespread use of abdominal imaging has definitely contributed to increased detection of RCC, but fails to account for it entirely,” Dr. Lowrance said. “A number of studies have suggested that obesity could be a risk factor for RCC, but the exact reason is unknown. Researchers suggest it might be secondary to hormonal changes, decreased immune function, hypertension or diabetes in obese patients.”

Obesity, defined as a BMI of more than 30 kg/m2, was present in 38% of patients. Median BMI was 28 kg/m2 (interquartile range, 25 – 32 kg/m2). BMI was significantly associated with clear-cell histologic features, after adjustment for tumor size, age, sex, American Society of Anesthesiologists score, estimated glomerular filtration rate, hypertension, diabetes mellitus, and smoking.

For each unit of BMI, the odds ratio (OR) was 1.04 (95% confidence interval [CI], 1.02 – 1.06; P < .001), and OR was 1.48 for obese vs nonobese patients (95% CI, 1.19 – 1.84; P < .001). BMI was still an independent predictor of clear-cell histology in the subgroup of patients with RCC (excluding benign renal cortical tumors; OR, 1.04; 95% CI, 1.02 – 1.06; P = .001).

“We also looked at other health and lifestyle factors, like diabetes, hypertension and smoking,” Dr. Lowrance said. “This showed that the only other factors that were independent predictors of clear-cell RCC were male gender and tumour size.”

Limitations of this study include retrospective case series, lack of a control group, referral/selection bias, and BMI calculation at a single point in time.

“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,” Dr. Lowrance concluded. “Of these, obesity provides the strongest association.”

The Stephen Hanson Family Fellowship, National Institutes of Health, and the Sidney Kimmel Center for Prostate and Urologic Cancers supported this study. The study authors have disclosed no relevant financial relationships.

BJU Int. 2010;105:16-20.

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