[Explaining cancer incidence in the Jejudo population]

The necessity of an observational study on the interactions between allergic history and citrus fruit intake for the prevention of pancreatic cancer

While the main product of Jeju Island is citrus fruit and the prevalence of atopic dermatitis among the students who live there is relatively high, the incidence of pancreatic cancer is lowest in Korea. Systematic reviews reporting allergic history and intake of citrus fruit as protective factors against pancreatic cancer (PCC) were published in 2005 and 2008, respectively. Although there were discrepancies in the results of the subgroup analyses between case-control and cohort studies, it is necessary to evaluate an interaction effect between allergic history and intake of citrus fruits on PCC risk.

Citrus fruit intake and breast cancer risk: a quantitative systematic review

PURPOSE

We investigated the association between dietary intake of citrus fruits and breast cancer risk.

METHODS

The PubMed and EMBASE were searched for relevant articles on diet and breast cancer up to January 2012. All of the epidemiological studies that assessed dietary intake of citrus fruits and presented risk estimates of the association between citrus fruits intake and risk of breast cancer were reviewed. Multivariable-adjusted odds ratios (OR) and associated 95% confidence intervals (CI) for highest versus lowest intake of dietary citrus fruits level were extracted. Overall summary OR was calculated by using a fixed-effect meta-analysis.

RESULTS

Six case-control studies out of five articles were eligible. Overall summary OR showed a 10% reduction in risk of breast cancer associated with high intake of citrus fruits (summary OR, 0.90; 95% CI, 0.85-0.96; p<0.001); results were consistent across the studies (I (2)=0). Visual inspection of the results did not suggest a publication bias.

CONCLUSION

Pooled results from observational studies showed an inverse association between citrus fruits intake and the risk of breast cancer.

Extracts from Citrus unshiu promote immune-mediated inhibition of tumor growth in a murine renal cell carcinoma model

AIM OF THIS STUDY

Citrus unshiu (Satsuma mandarin, SM) is a citrus fruit the peel of which has been used as a traditional Chinese medicine to treat common cold, relieve exhaustion, and cancer. In this study, we examined how effectively the content and peel extracts of SM can suppress cancer growth. The mechanism underlying cancer-suppressing properties of SM was investigated in tumor-bearing mice with renal carcinoma cell, Renca.

MATERIALS AND METHODS

Effectiveness of SM in tumor suppression was evaluated by measuring size of tumor mass in tumor-bearing mice treated with various doses of SM content and peel extracts. Proliferation of tumor cells and splenocytes was determined by MTT assay and [³H]TdR uptake, respectively. Relevant immunological mechanisms were chased by assaying cytokines including TGF-β, IL-6, IFN-γ, and TNF-α by ELISA.

RESULTS

The content and peel extracts of SM inhibited the growth of tumor cells in tumor-bearing mice. Especially, average tumor volume of two groups treated with 3 and 30 mg peel extracts per mouse weight (kg) were significantly decreased to 52.32% (p<0.05) and 68.72% (p<0.01), respectively. To identify tumor regression mechanism, anti-tumor cytokines measured in Con A-activated splenocytes from tumor-bearing mice. IFN-γ was increased in both of the peel extract-treated groups, while TNF-α, which had been decreased by tumor growth, was rescued to the normal level in SM content and peel extracts-treated groups. However, SM content and peel extracts did not inhibit proliferation and tumor-proliferative cytokines including TGF-β and IL-6 production of tumor cells.

CONCLUSION

These results indicate that SM content and peel extracts have anti-tumor properties in the tumor-bearing murine model. The mechanism underlying the anti-tumor effects of SM extracts is strongly suggested to be via boosting cytokines such as IFN-γ and TNF-α, enhancing immune-mediated anti-tumor properties.