medwireNews: Patients with renal cell carcinoma (RCC) are at increased risk for recurrence following surgery if they also have Type 2 diabetes, a retrospective analysis shows.
This risk for recurrence appeared to be particularly strong among obese patients, whose risk increased fourfold.
“This finding indicates the prognostic significance of [diabetes mellitus] with obesity for RCC patients,” say researchers Hitoshi Masuda (Tokyo Medical and Dental University, Japan) and colleagues.
They evaluated 543 patients with non-metastatic RCC who underwent radical or partial nephrectomy.
Recurrence occurred in 68 (12.5%) patients over an average follow up of 66.7 months. And the risk for such an outcome was increased a significant 2.43-fold among the 82 (15.1%) patients who had a history of diabetes, compared with nondiabetic patients.
Diabetes was an independent predictor for recurrence, along with tumor diameter, grade, and pathologic T stage.
But when the effects of obesity were taken into consideration, a strong association between diabetes and risk for recurrence remained only for the 157 (28.9%) obese patients weighing at least 25 kg/m2, and not for the non-obese patients. The hazard ratios were 4.07 and 1.95, respectively.
Among the obese patients, the 5-year recurrence-free survival rate was significantly lower for those with diabetes than for those without, at 75.3% versus 91.9%.
Given previous evidence of an association between diabetes and recurrence in obese individuals with other malignant diseases, such as breast, endometrial, and prostate cancer, the researchers say that “[diabetes mellitus] with obesity may be involved in carcinogenesis and cancer development.”
They also suggest that the association may be related to the timing and order of diabetes and cancer onset. Patients in the early phase of Type 2 diabetes are usually obese and have an increased bioavailability of insulin-like growth factor (IGF)-1, which creates an environment favoring cancer growth, they explain.
Over time, however, patients with diabetes become thinner and develop hypoinsulinemia, creating a harsh environment for cancer growth.
Indeed, in further analyses they found that insulin secretory capacity in diabetes patients was higher in those who were obese than non-obese, and that diabetes was strongly associated with renal cancer recurrence in patients younger than 65 years but not in older patients.
“Therefore… patients with the early phase of [diabetes mellitus] tend to be obese and may therefore have a high risk of RCC progression,” the team comments in the Japanese Journal of Clinical Oncology.
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