Table 3. Multivariable Fine-Gray Competing Risk Models for Breast Cancer–Specific Mortality: Comparison of Interval Breast Cancers and Breast Cancers Detected by Screening After Controlling for Baseline Health and Tumor Characteristics.

Model	Breast cancer type, hazard ratio (95% CI)a
	Detected by screening	Interval breast cancer <1 y	Interval breast cancer 1-2.5 y
1b	1 [Reference]	1.81 (1.30-2.51)	1.17 (0.88-1.56)
2c	1 [Reference]	1.64 (1.17-2.29)	1.12 (0.83-1.50)
3d	1 [Reference]	1.66 (1.18-2.33)	1.17 (0.86-1.60)
4e	1 [Reference]	1.69 (1.20-2.37)	1.17 (0.86-1.60)
5f	1 [Reference]	1.46 (1.03-2.08)	1.12 (0.82-1.53)
6g	1 [Reference]	1.34 (0.96-1.88)	1.13 (0.83-1.55)
7h,i	1 [Reference]	1.24 (0.87-1.77)	1.09 (0.79-1.51)

^aThis table reports a series of sequential multivariable models in which a new variable is added to each model. Numbers in cells represent the hazard ratios and 95% CIs computed from the Fine-Gray competing risk model. Time is calculated as the time between diagnosis date and end of follow-up. Interval breast cancers were subdivided by their interscreening period: those diagnosed within 1 year of last screening or between 1 and 2.5 years since last screening.

^bFine-Gray competing risk models for breast cancer–specific mortality by breast cancer type adjusting for molecular subtype as the covariate.

^cIncludes all variables in model 1 with additional adjustment for histologic type.

^dIncludes all variables in model 2 with additional adjustment for hormone replacement therapy clinical trial group and dietary modification trial group.

^eIncludes all variables in model 3 with additional adjustment for waist to hip ratio.

^fIncludes all variables in model 4 with additional adjustment for tumor size.

^gIncludes all variables in model 5 with additional adjustment for lymph node involvement.

^hIncludes all variables in model 6 with additional adjustment for other common risk factors for breast cancer (age at diagnosis, race/ethnicity, family history of breast cancer, comorbidity, total number of mammograms before diagnosis, age at menarche, age at first birth, income, educational level, smoking status, alcohol intake, and body mass index).

ⁱIf adding the common risk factors in model 7 before adding tumor size and lymph node into the model, the corresponding hazard ratio for interval breast cancer within 1 year is 1.64 (95% CI, 1.14-2.34) and for interval breast cancer between 1 and 2.5 years is 1.16 (95% CI, 0.84-1.59).