Dietary intake of tomato and lycopene, blood levels of lycopene, and risk of total and specific cancers in adults: a systematic review and dose-response meta-analysis of prospective cohort studies

Arghavan Balali ¹ Kimia Fathzadeh ² Gholamreza Askari ¹ Omid Sadeghi ^1*

• ¹ Isfahan University of Medical Sciences, Isfahan, Iran
• ² Tehran University of Medical Sciences, Tehran, Tehran, Iran

The association between tomato/lycopene intake and blood levels of lycopene with the risk of specific cancers were assessed in previous meta-analyses; however, no study evaluated the risk of overall cancer incidence/mortality. Therefore, the present systematic review and dose-response meta-analysis aimed to summarize available findings from prospective studies to examine the association between tomato/lycopene intake and lycopene levels with the risk of total and specific cancers and cancer-related mortality.Methods: A comprehensive literature search was done using Scopus, PubMed, ISI Web of Science, and Google Scholar until July 2023.Results: In total, 121 prospective studies were included in the systematic review and 119 in the meta-analysis. During the follow-up period of 2 to 32 years, a total of 108,574 cancer cases and 10,375 deaths occurred. High intakes and high levels of lycopene compared to low amounts were respectively associated with 5% (Pooled RR: 0.95, 95% CI: 0.92 to 0.98, I 2 =26.4%, P=0.002) and 11% (Pooled RR: 0.89, 95% CI: 0.84 to 0.95, I 2 =15.0%, P<0.001) reduction in overall cancer risk. Also, each 10 µg/dL increase in blood levels of lycopene was associated with a 5% lower risk of overall cancer. Moreover, we found a linear inverse association between dietary lycopene intake and prostate cancer risk (Pooled RR 0.99, 95% CI 0.97 to 1.00, I 2 =0, P=0.045). Regarding cancer mortality, negative relationships were found with total tomato intake (Pooled RR: 0.89, 95% CI: 0.85 to 0.93, I 2 =65.7%, P<0.001), lycopene intake (Pooled RR: 0.84, 95% CI: 0.81 to 0.86, I 2 =86.5%, P<0.001) and lycopene levels (Pooled RR 0.76, 95% CI: 0.60 to 0.98, I 2 =70.9%, P=0.031). Also, an inverse association was observed between blood lycopene levels and lung cancer mortality (Pooled RR: 0.65, 95% CI: 0.45 to 0.94, I2=0, P=0.022).Our findings show that dietary intake and blood levels of lycopene are associated with a lower risk of cancer and death due to cancer.