Obesity Linked to Increased Mortality in Prostate Cancer Survivors

Obesity was associated with increased cardiovascular disease-related mortality and all-cause mortality, as well as potentially increased prostate cancer-specific mortality, in survivors of nonmetastatic prostate cancer, according to data published in the Journal of Clinical Oncology.

“Our results suggest that among survivors of nonmetastatic prostate cancer, postdiagnosis obesity may be associated with higher (cardiovascular disease-related mortality) and all-cause mortality and that postdiagnosis weight gain may be associated with a higher mortality as a result of all causes and prostate cancer,” the authors wrote.

To identify associations of postdiagnosis body mass index (BMI) and weight change with cause-specific and all-cause mortality in patients with nonmetastatic prostate cancer, researchers identified 11,788 patients from the Cancer Prevention Study II Nutrition Cohort diagnosed with prostate cancer between 1992 and 2013. The cohort, a prospective study of cancer incidence and mortality, originally initiated in the early 1990s and enrolled participants from 21 states and included a patient subset from another study started by the American Cancer Society in 1982.

A baseline BMI was taken from the first survey 8,330 patients completed within the first six years after diagnosis. Patients (6,942) then completed follow-up questionnaires every two years after diagnosis to track changes in weight.

The primary outcome of the study was prostate cancer-specific mortality. Additional secondary outcomes included cardiovascular disease-related mortality and all-cause mortality.

Researchers observed 3,855 deaths in the analysis of postdiagnosis BMI, of which 500 were disease-specific deaths and 1,155 were cardiovascular disease-related deaths.

Men who had a BMI of 30 kilograms (kg)/m² or greater were more likely to experience prostate cancer-specific mortality compared to men who had a BMI between 18.5 kg/m² and 25 kg/m². Additionally, cardiovascular disease-related mortality was higher among men who had a BMI of 30 kg/m² or greater, which was considered obese.

Patients who gained more than 5% of their weight after diagnosis had a higher risk of prostate cancer—specific mortality vs. those who maintained stable weight, which translated into worse all-cause mortality.

Patients who reported being overweight at diagnosis and eventually developed an obese BMI following prostate cancer diagnosis had a higher risk of prostate cancer—specific mortality.

Almost half (49%) of the patients within the BMI cohort were considered to be overweight, 16% were considered to be obese and 36% had a healthy weight. Prostate cancer-specific mortality was also higher in men who were overweight, but there were no associations with an increased risk of cardiovascular disease—related mortality or all-cause mortality.

“Survivors of prostate cancer are advised to maintain a healthy weight and avoid weight gain, and our findings provide additional evidence to follow these recommendations,” the researchers wrote. “This may be especially important given evidence that survivors of prostate cancer may be more prone to weight gain compared with men in the general population.”

However, patients who had lost 3% to 5% of their body weight also had a heightened risk of all-cause mortality, as well as those who lost more than 5% of their body weight. The researchers wrote that their results would not necessarily support weight loss among prostate cancer survivors but highlighted how the association between weight loss and all-cause mortality is most likely a result of an underlying disease.

“Future studies are needed to determine whether intentional weight loss provides health benefits among overweight and obese survivors of prostate cancer,” the researchers concluded.

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