Table 4.

Breast cancer–specific MRRs stratified by age at diagnosis, California, 2005–2014

Younger (18–49)Older (50+)
Number of deaths due to breast cancerMRR (95% CI)aMRR (95% CI)bNumber of deaths due to breast cancerMRR (95% CI)aMRR (95% CI)b
All2,2366,233
Tumor subtype
 HR+/HER2820ReferenceReference2,781ReferenceReference
 HR+/HER2+2361.11 (0.96–1.29)0.80 (0.69–0.93)5981.69 (1.55–1.85)1.05 (0.95–1.15)
 HR/HER2+2142.45 (2.11–2.851.37 (1.15–1.62)4762.86 (2.60–3.16)1.28 (1.14–1.43)
 Triple negative7383.88 (3.51–4.29)2.50 (2.19–2.86)1,5184.26 (4.00–4.54)2.35 (2.17–2.53)
 Unclassified2281.29 (1.11–1.49)1.11 (0.96–1.29)8601.56 (1.44–1.68)1.25 (1.16–1.36)
P interaction = 0.0008c
NCICC
 No1,901ReferenceReference5,784ReferenceReference
 Yes3351.08 (0.96–1.22)1.00 (0.89–1.13)4490.94 (0.86–1.04)0.84 (0.76–0.93)
P interaction = 0.003c
Guideline-concordant treatment
 Yes1,409ReferenceReference2,879ReferenceReference
 No2301.25 (1.09–1.44)1.20 (1.03–1.40)6571.47 (1.35–1.60)1.49 (1.36–1.63)
 Not available5900.32 (0.29–0.36)1.00 (0.88–1.15)2,6830.31 (0.29–0.32)1.14 (1.05–1.24)
 Unknown70.95 (0.45–2.00)0.59 (0.27–1.30)141.09 (0.65–1.85)0.79 (0.45–1.40)
P interaction = 0.015c
  • aAdjusted for year at diagnosis.

  • bStratified by AJCC stage, and adjusted for year of diagnosis, age at diagnosis (continuous), marital status, race/ethnicity, insurance status, nSES, lymph node involvement, tumor size, tumor grade, tumor histology, and clustering by block group.

  • cP for interaction between age group (younger and older) and tumor subtype, NCICC, or guideline-concordant treatment (excluding unknown) from a model which included all significant interactions with age group.