Adding a little more watermelon, tomatoes and papaya to your diet may help lower your risk for kidney cancer, according to a study published in Cancer.

Researchers at Wayne State University looked at 96,196 women and found that those who ingested higher amounts of lycopene has a 39% lower risk of developing renal cell carcinoma (RCC).1

“That is a pretty good reduction in risk,” said study investigator Cathryn Bock, PhD, MPH, who is an associate professor of oncology at Wayne State University’s School of Medicine in Detroit, MI.

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Dr. Bock said RCC is often diagnosed in a more advanced stage and so greater efforts are needed to lower mortality and better understand contributing factors.

In 2014, it was estimated that there were 63,920 new cases of kidney cancer in the United States, with an overall 5-year survival rate of approximately 70%, according to the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program (SEER).2

It has been theorized that oxidative stress plays an important role in RCC pathogenesis. The Detroit researchers analyzed the risks for RCC associated with intake of a-carotene, b-carotene, b-cryptoxanthin, lutein plus zeaxanthin, lycopene, vitamin C, and vitamin E in women enrolled in the Women’s Health Initiative (WHI) between 1993 and 1998.

The women were followed through July 2013 and dietary micronutrient intake was estimated from food frequency questionnaires and data on supplement use were collected through interviews.

The researchers found that 242 women with RCC were identified during follow-up and lycopene intake was inversely associated with RCC risk compared with the lowest quartile of lycopene intake.

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Dr. Bock said the highest quartile of intake was associated with a 39% lower risk of RCC, while no other micronutrient was significantly associated with RCC risk.

“You don’t need a crazy amount. You can get plenty with just a half a grapefruit or two tomatoes. So you don’t need to go overboard,” Dr. Bock said in an interview with Cancer Therapy Advisor. “I would never recommend supplements unless your doctor does.”

She said she was surprised to observe a protective effect of lycopene since several previous studies in other populations did not detect a similar relationship.

She said that smoking is a major RCC risk factor and this cohort included a relatively small percentage of smokers.

“This is just women and they were all postmenopausal. It could have something to do with hormones and just being female,” said Dr. Bock.

She and her colleagues are now examining whether there is a relationship between antioxidant nutrient intake and RCC risk in a case-control study primarily conducted with participants from the metropolitan Detroit area.

The study includes a broader population (men and women) and a greater representation of African-Americans. Studies have suggested that lycopene may have a protective affect against the development of some breast cancers and prostate cancers.