Previous studies have suggested that serum carotenoids may be associated with risk of gastrointestinal tract cancer (GIT cancer), but the results were inconsistent. Thus, the investigators conducted a meta-analysis to evaluate the associations between serum carotenoids and risk of GIT cancer.

Inclusion Criteria:

• The study had both case and control groups
• Serum carotenoids levels, relative risk (RR) or OR and corresponding 95% CI were reported
• Patients in case group were diagnosed with GIT cancer

Exclusion Criteria:

·Animal studies

The study population include people from primary care clinic or community sample.