Table 1

Summary risk estimates and corresponding 95% CIs for prostate cancer associated with the highest versus the lowest coffee consumption

No of studiesSummary RR95% CII2 (%)P value*
Overall150.91(0.84 to 0.98)53.20.008
Prostate cancer category †
 Localised60.93(0.87 to 0.99)37.00.159
 Advanced80.88(0.71 to 1.09)52.70.039
 Fatal60.84(0.66 to 1.08)46.30.097
Study location
 North America70.96(0.90 to 1.03)17.70.295
 Europe60.85(0.74 to 0.98)63.30.018
 Japan20.85(0.48 to 1.51)68.50.075
NOS score
 621.20(0.84 to 1.72)00.507
 731.02(0.78 to 1.32)00.810
 8 or 9100.88(0.81 to 0.96)66.20.002
Adjustment for confounders
PSA testing ‡
 Yes60.86(0.77 to 0.96)31.80.197
 No90.94(0.84 to 1.06)60.50.009
Family history of prostate cancer
 Yes40.83(0.72 to 0.96)57.80.068
 No110.95(0.85 to 1.05)50.80.026
Total energy intake
 Yes60.85(0.76 to 0.96)61.10.025
 No90.97(0.85 to 1.09)47.70.053
Smoking status
 Yes100.86(0.79 to 0.94)52.00.027
 No51.03(0.95 to 1.11)00.805
Alcohol consumption
 Yes60.87(0.84 to 0.98)49.20.008
 No90.93(0.84 to 1.03)57.20.017
Physical activity
 Yes70.87(0.79 to 0.95)58.40.025
 No81.00(0.90 to 1.12)10.50.348
BMI
 Yes90.86(0.78 to 0.94)56.90.017
 No61.03(0.95 to 1.11)00.897
Diabetes
 Yes50.87(0.84 to 0.98)64.90.022
 No100.97(0.86 to 1.10)22.80.233
  • *P value for heterogeneity within each subgroup.

  • †Based on definition in each original study, the prostate cancer categories were classified as follows: (a) localised prostate cancer which included localised or non-aggressive cancers, (b) advanced prostate cancer which included advanced or aggressive cancers, (c) fatal prostate cancer which included fatal/lethal cancers or prostate cancer-specific deaths.

  • ‡Since PSA testing was generally introduced after 1986, studies with follow-up periods that ended before 1986 were classified in the PSA-adjusted group.

  • BMI, body mass index; NOS, Newcastle–Ottawa Scale; PSA, prostate-specific antigen; RR, relative risk.