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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

Ā 

Criteria used

Decreased risk

Increased risk

Strong

P in random-effects modelā€‰<ā€‰=ā€‰ā€‰ 0.001 Number of cases >ā€‰1000 I2ā€‰<ā€‰=ā€‰50% 95% predictive intervals exclude the null value Small study effects Pā€‰>ā€‰0.1 Excess significance bias Pā€‰>ā€‰0.1

None

Acute lymphocytic leukemia (H/L)

Highly suggestive

P in random-effects modelā€‰<ā€‰=ā€‰ 0.001Number of cases >ā€‰1000 I2Ā <ā€‰=ā€‰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)

Suggestive

P in random-effects modelā€‰<ā€‰=ā€‰ 0.001Number of cases >ā€‰500

None

Lung cancer (H/L)

Weak

P in random-effects model <= 0.05

Breast 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 association

P in random-effects model >ā€‰0.05

Pancreatic 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