Aims/hypothesis: Individuals with diabetes are at increased risk of developing and dying from cancer. Evidence-based guidelines recommend universal screening for breast, cervical and colorectal cancer; however, evidence on the uptake of these tests in individuals with diabetes is mixed. We conducted a meta-analysis to quantify the association between diabetes and participation in breast, cervical and colorectal cancer screening.
Methods: MEDLINE, EMBASE and CINAHL were searched systematically for publications between 1 January 1997 and 18 July 2018. The search was supplemented by handsearching of reference lists of the included studies and known literature reviews. Abstracts and full texts were assessed in duplicate according to the following eligibility criteria: study conducted in the general population; diabetes included as a predictor vs a comparison group without diabetes; and breast (mammography), cervical (Papanicolaou smear) or colorectal (faecal and endoscopic tests) cancer screening uptake included as an outcome. Random-effects meta-analyses were performed using the most-adjusted estimates for each cancer site.
Results: Thirty-seven studies (25 cross-sectional, 12 cohorts) were included, with 27 studies on breast, 19 on cervical and 18 on colorectal cancer screening. Having diabetes was associated with significantly lower likelihood of breast (adjusted OR 0.83 [95% CI 0.77, 0.90]) and cervical (OR 0.76 [95% CI 0.71, 0.81]) cancer screening, relative to not having diabetes. Colorectal cancer screening was comparable across groups with and without diabetes (OR 0.95 [95% CI 0.86, 1.06]); however, women with diabetes were less likely to receive a colorectal cancer screening test than women without diabetes (OR 0.86 [95% CI 0.77, 0.97]).
Conclusions/interpretation: Our findings suggest that women with diabetes have suboptimal breast, cervical and colorectal cancer screening rates, compared with women without diabetes, although the absolute differences might be modest. Given the increased risk of cancer in this population, higher quality prospective evidence is necessary to evaluate the contribution of diabetes to cancer screening disparities in relation to other patient-, provider- and system-level factors.
Registration: PROSPERO registration ID CRD42017073107.
Keywords: Breast cancer; Cancer screening; Cervical cancer; Colorectal cancer; Diabetes management; Diabetes mellitus; Healthcare barriers; Healthcare disparities; Meta-analysis; Systematic review.