Diabetes, Metformin Use, and Colorectal Cancer Survival in Women - A Retrospective Cohort Study.
Observational studies have associated Metformin use with lower colorectal cancer
incidence but few studies have examined survival impact. We examined the relationship
between Metformin use, diabetes, and survival in postmenopausal women diagnosed with
colorectal cancer while participating in the Women's Health Initiative (WHI) Clinical
Trial or Observational Study. Metho... read moreds: 2,066 postmenopausal women with colorectal cancer
diagnosed while enrolled in the WHI were followed for a median of 4.1 years, with 589
deaths overall and 414 colorectal cancer deaths. In this cohort, overall and colorectal
cancer-specific survival were compared among women with diabetes who reported ever using
Metformin (n=84); those with no reported use of Metformin (n=128); and women without
diabetes (n=1854). Cox proportional hazard models were used to estimate the associations
between Metformin use, diabetes and survival outcomes from the time of colorectal cancer
diagnosis. Two strategies were used to adjust for potential confounders: multivariate
adjustment with known predictors of colorectal cancer survival and construction of a
propensity score for the likelihood of receiving Metformin, with model stratification by
propensity score quintile. Results: After adjusting for age and stage at diagnosis,
women with diabetes on Metformin had no significant difference in colorectal-cancer
specific survival compared to Metformin non-users (HR 0.75; 95% CI 0.40 -1.38, p=0.67)
or compared to women without diabetes (HR 1.00; 95% CI 0.61 - 1.66, p=0.99). With
propensity score adjustment, the HR for colorectal cancer-specific survival in women
with diabetes on Metformin compared to non-users was 0.90 (95% CI 0.48 - 1.69, p=0.75).
Women with diabetes reporting Metformin use had no significant difference in overall
survival compared to non-users (HR 0.84; 95% CI 0.51 - 1.37; p=0.48) or non-diabetics
(HR 1.20; 95% CI 0.80 - 1.79; p=0.39). Conclusions: In postmenopausal women with
colorectal cancer and diabetes, no statistically significant difference was seen in
colon-cancer specific survival in those who used Metformin. Analyses in larger
populations of colorectal cancer patients are
Thesis (M.S.)--Tufts University, 2012.
Submitted to the Dept. of Clinical & Translational Science.
Advisor: Jessica Paulus.
Committee: Robert Martell, and David Kent.
Keyword: Medicine.read less