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Approved research

Association between citrus consumption and skin cancer: an analysis of risk and nutrient-gene interaction

Principal Investigator: Mr Andrew Marley
Approved Research ID: 49419
Approval date: July 12th 2019

Lay summary

In the United States, rates of melanoma and NMSC have increased substantially over the past several decades. This increase in incidence has been particularly considerable among fair-skinned/Caucasian populations. NMSC is the most common malignancy in the United States, with an estimated 5.4 million cases and 18,000 deaths annually. Melanoma, the deadliest form of skin cancer, is now the 5th and 6th most common cancer among American men and women, respectively. Although exposure to UV radiation remains the primary risk factor for skin cancer, recent studies have demonstrated that higher citrus consumption is associated with an increased risk of melanoma and NMSC. Among individual citrus fruits studied, grapefruit consumption was associated with the highest skin cancer risk. Although in need of further confirmation, these findings are reasonable to believe. Citrus fruits naturally contain compounds called psoralens, a type of furocoumarin that is known to increase risk of skin cancer. Other factors, such as certain physical or genetic characteristics, can also influence susceptibility to skin cancer. We know that people with lighter skin, fairer hair, who spend a lot of time outdoors, or who burn easily are more likely to get skin cancer. However, we do not know if a high consumption of citrus fruits would further increase skin cancer risk in these people. Also, while we do know that certain genes can contribute to skin cancer risk, we do not know if people with these genes, who also have a high citrus consumption, are more likely to develop skin cancer than people who just have the genetic predisposition alone. We also know very little about the genetics behind citrus metabolism and/or what genes may be involved with the increased risk of skin cancer associated with citrus. Because of that, it is my goal over the next 18 months to: investigate whether high consumption of citrus is associated with melanoma and NMSC in this data set; to analyze whether other skin cancer risk factors influence risk from citrus; and search for genetic markers that may influence skin cancer risk from citrus. If our assumptions are correct, this research will provide the public with a simple, practical, cost-effective, non-burdensome strategy for reducing skin cancer risk. This research will also increase our understanding of citrus metabolism and how genetics may play a role in this association.