Table 2.
Association between type 2 diabetes and breast cancer, The Sister Study
| Total breast cancer | ER+ breast cancer | ER− breast cancer | TNBC | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| No. of cases | Age-adjusted HR (95% CI) * | Multivariable-adjusted HR (95% CI) † | No. of cases | Multivariable-adjusted HR (95% CI) † | No. of cases | Multivariable-adjusted HR (95% CI) † | No. of cases | Multivariable-adjusted HR (95% CI) † | ||
| Presence of T2D | No | 2401 | 1 (reference) | 1 (reference) | 1800 | 1 (reference) | 303 | 1 (reference) | 155 | 1 (reference) |
| Yes | 277 | 1.02 (0.90-1.16) | 0.99 (0.87-1.13) | 184 | 0.92 (0.78-1.07) | 36 | 1.07 (0.75-1.53) | 25 | 1.40 (0.90-2.16) | |
| Time since T2D diagnosis (y) | No T2D | 2401 | 1 (reference) | 1 (reference) | 1800 | 1 (reference) | 303 | 1 (reference) | 155 | 1 (reference) |
| < 5 | 129 | 1.07 (0.90-1.28) | 1.03 (0.86-1.23) | 90 | 0.98 (0.79-1.22) | 19 | 1.21 (0.76-1.93) | 12 | 1.46 (0.81-2.63) | |
| 5 -<10 | 81 | 1.03 (0.83-1.29) | 1.00 (0.80-1.25) | 53 | 0.91 (0.69-1.21) | 9 | 0.95 (0.49-1.84) | 8 | 1.55 (0.76-3.16) | |
| 10 -<15 | 40 | 1.07 (0.78-1.46) | 1.03 (0.75-1.41) | 26 | 0.96 (0.65-1.43) | 8 | 0.94 (0.47-1.90) | 5 | 1.09 (0.44-2.69) | |
| ≥ 15 | 27 | 0.78 (0.53-1.13) | 0.76 (0.52-1.12) | 15 | 0.61 (0.37-1.03) | |||||
| P trend | 0.74 | 0.45 | 0.10 | 0.99 | 0.26 | |||||
Abbreviations: T2D, type 2 diabetes; ER, estrogen receptor; HR, hazard ratio; 95% CI, 95% confidence interval; +, positive; −, negative; TNBC, triple-negative breast cancer.
Adjusted for age (age as the primary time scale)
Adjusted for race/ethnicity (non-Hispanic white, non-Hispanic black, or other), educational attainment (high school degree or less, some college, college degree or higher), height, body mass index (BMI) at 30-39 years old (<18.5, 18.5 to <25, 25 to <30, 30 to <35, 35 to <40, or ≥40 kg/m2), physical activity (metabolic equivalent hours/week), recent mammogram screening (<1 y, 1 to 2y, >2y), age at menarche ≤11 years old, number of relatives diagnosed with breast cancer (1, ≥2), and birth cohort (born in <1945, 1945 to <1955, 1955 to <1965 or ≥1965), as well as time varying covariates including BMI, menopausal status (binary), interaction term between BMI and menopausal status, age at menopause, alcohol consumption (never drinker, former drinker, current drinker <1 drink/day, current drinker 1-1.9 drinks/day, current drinker ≥2 drinks/day), smoking status (≥20 pack-years, <20 and ≥10 pack-years, <10 and >0 pack-years, never smoker), use of any hormonal birth control (never, ever), hormone therapy (none, estrogen only, both estrogen and progesterone), age at first childbirth (nulliparous, <21 years, 21 to <25 years, 25 to <29 years, or ≥29 years), lifetime duration of breastfeeding (weeks, none and tertiles among women with any breastfeeding), and parity (0, 1, 2, ≥3 births).