Recreational physical activity and risk of triple negative breast cancer in the California Teachers Study

Breast Cancer Research

Table 4 Adjusted hazard ratios for the associations between strenuous recreational physical activity and invasive breast cancer subtypes by menopausal hormone therapy use

	Cases, no.	Strenuous RPA, h/wk/y			P _trend	P _{homogeneity of trends}
	Cases, no.	≤0.50	0.51–3.50	≥3.51		P _{homogeneity of trends}
		Adjusted HR (95 % CI)	Adjusted HR (95 % CI)	Adjusted HR (95 % CI)
TNBC (ER-/PR-/HER2-)
Long-term^a
Never MHT use at baseline	37	Referent	1.43 (0.72–2.84)	0.35 (0.08–1.56)	0.23	0.32
Ever MHT use at baseline	165	Referent	0.93 (0.66–1.32)	0.91 (0.54–1.52)	0.69
Baseline^b
Never MHT use at baseline	37	Referent	0.92 (0.43–1.98)	0.43 (0.10–1.83)	0.26	0.65
Ever MHT use at baseline	165	Referent	1.00 (0.70–1.44)	0.60 (0.32–1.13)	0.14
Luminal A-like (ER+ or PR+ plus HER2-)
Long-term^a
Never MHT use at baseline	315	Referent	0.92 (0.72–1.17)	0.86 (0.61–1.20)	0.36	0.75
Ever MHT use at baseline	1357	Referent	0.92 (0.81–1.04)	0.91 (0.76–1.09)	0.28
Baseline^b
Never MHT use at baseline	315	Referent	0.83 (0.63–1.09)	0.73 (0.50–1.07)	0.07	0.15
Ever MHT use at baseline	1357	Referent	0.92 (0.81–1.05)	0.97 (0.81–1.16)	0.57

Results are for 53,394 peri- and postmenopausal women who never used MHT or ever used E only, E + P only or mixed formulations at baseline. HRs are from multivariable Cox proportional hazards regression models using age (in days) as the time metric and stratified by age (in years) with the adjustment for race, family history of breast cancer in first-degree relatives, combined age at first full-term pregnancy and parity variable, BMI at baseline, history of smoking, alcohol intake during the past year of baseline, screening mammogram in the past 2 years of baseline, history of a breast biopsy, and a corresponding moderate RPA variable
Abbreviations: BMI body mass index, CI confidence interval, E estrogen, ER estrogen receptor, HER2 human epidermal growth factor receptor 2, HR hazard ratio, h/wk/y hour/week/year, MHT menopausal hormone therapy, P progestin, PR progesterone receptor, RPA recreational physical activity, TNBC triple negative breast cancer
^aRPA from high school till age 54 or age at cohort entry, whichever was younger
^bRPA during the 3 years prior to baseline

ISSN: 1465-542X