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Table 3 Summary of evidence grading for meta-analyses associating coffee intake with cancer incidence Level of evidence

From: Coffee drinking and cancer risk: an umbrella review of meta-analyses of observational studies

 Criteria usedDecreased riskIncreased risk
StrongP in random-effects model < =   0.001 Number of cases > 1000 I2 < = 50% 95% predictive intervals exclude the null value Small study effects P > 0.1 Excess significance bias P > 0.1NoneAcute lymphocytic leukemia (H/L)
Highly suggestiveP in random-effects model < =  0.001Number of cases > 1000 I2 < = 75%Endometrial cancer (H/L); Endometrial cancer (Per 1 cup); Liver cancer (H/L); Liver cancer (Per 1 cup); Melanoma (H/L); Oral cancer (H/L); Oral/pharyngeal cancer (H/L)Bladder (H/L)
SuggestiveP in random-effects model < =  0.001Number of cases > 500NoneLung cancer (H/L)
WeakP in random-effects model <= 0.05Breast cancer (Per 1 cup); Colon cancer (Per 1 cup); Colorectal cancer (H/L); Esophageal cancer (H/L); Nonmelanoma (H/L)Leukemia (H/L); Lung (Per 1 cup)
No associationP in random-effects model > 0.05Pancreatic cancer (H/L); Breast cancer (H/L); Colon cancer (H/L); Ovarian cancer (H/L); Acute myelogenous leukemia (H/L); Pancreatic cancer (Per 1 cup); Rectal cancer (Per 1 cup); Kidney cancer (H/L); Laryngeal cancer (H/L); Rectal cancer (H/L); Colorectal cancer (Per 1 cup); Thyroid cancer (H/L); Prostate cancer (H/L); Gastric cancer (Per 1 cup); Gastric cancer (H/L); Lymphoma (H/L); Glioma (Per 1 cup); Glioma (H/L); Biliary tract cancer (H/L).
  1. H/L Highest intake vs. lowest intake of coffee