Could Tomatoes Lower Kidney Cancer Risk in Older Women?
Postmenopausal women with a greater dietary intake of lycopene may have a lower risk of kidney cancer, according to a recent study in the journal Cancer.
“Women who consumed more than 6.43 mg of lycopene—equivalent to one and a half tomatoes—on average daily were at 39% lower risk of developing renal cell carcinoma compared to women in the lowest lycopene intake,” says principal investigator Cathryn Bock, PhD, MPH, associate professor of Oncology at Wayne State University’s School of Medicine in Detroit, Mich.
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The most common type of kidney cancer, renal cell carcinoma accounts for 9 out of 10 cases of kidney cancer, according to the American Cancer Society. It’s also the 8th leading cancer among women.
Oxidative stress has been considered to play an important role in its pathogenesis, so Bock and her team wanted to investigate whether there was any correlation between antioxidant micronutrients and the risk of developing renal cell carcinoma.
Bock and her colleagues analyzed data from 96,196 women nationwide who enrolled in the Women’s Health Initiative from 1993 to 1998 and were followed through July 2013 by participating initiative sites, including Wayne State University.
They looked at the risks for kidney cancer associated with intake of lycopene and other micronutrients that have antioxidant properties, including α-carotene, β-carotene, β-cryptoxanthin, lutein plus zeaxanthin, lycopene, vitamin C, and vitamin E.
During follow-up, 240 women were diagnosed with kidney cancer. Compared with women who reported the lowest intake of lycopene (less than 2.7 mg), those who ingested more had a 39% lower risk. No other micronutrient was significantly associated with the same risk.
“We did not perform any mechanistic studies; however, it has been suggested that micronutrients from diet or supplements may inhibit oxidative DNA damage, mutagenesis, and tumor growth,” Bock says.
In light of the study findings, she says it may be useful for health care providers to talk with patients about the benefits of a lycopene-rich diet within the context of also reducing well-established renal cell carcinoma risk factors, including smoking, obesity, hypertension, and lack of exercise.
“Intake at the level of the highest quartile (>6.4 mg), where we observe a protective effect, can be achieved through dietary intake of less than a daily single serving of tomato and tomato products, watermelon, or pink grapefruit,” Bock says. Guava and papaya are also good sources of lycopene.
Bock and her colleagues are currently examining whether there is a relationship between antioxidant nutrient intake and kidney cancer risk in a National Cancer Institute-funded case-control study primarily conducted with participants from the metropolitan Detroit area.
“This study included a broader population, including both men and women, and with greater representation of African Americans, and therefore may help describe the associations in populations beyond post-menopausal women who are primarily of European descent,” she says.
—Colleen Mullarkey
Reference
Ho WJ, Simon MS, Yildiz VO, Shikany JM, Kato I, Beebe-Dimmer JL, et al. Antioxidant micronutrients and the risk of renal cell carcinoma in the Women's Health Initiative cohort. Cancer. 2015 Feb 15; 121(4):580-8. DOI: 10.1002/cncr.29091.