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

Ma, Huiyan; Xu, Xinxin; Clague, Jessica; Lu, Yani; Togawa, Kayo; Wang, Sophia S.; Clarke, Christina A.; Lee, Eunjung; Park, Hannah L.; Sullivan-Halley, Jane; Neuhausen, Susan L.; Bernstein, Leslie

doi:10.1186/s13058-016-0723-3

Breast Cancer Research

Table 2 Adjusted hazard ratios for the associations between recreational physical activity and invasive breast cancer overall and by subtype

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

h/wk/y	Observed person-years	Overall		TNBC (ER-/PR-/HER2-)^a		Luminal A-like (ER+ or PR+ plus HER2-)^a
h/wk/y	Observed person-years	Cases, no.	Adjusted HR (95 % CI)	Cases, no.	Adjusted HR (95 % CI)	Cases, no.	Adjusted HR (95 % CI)
Total (strenuous plus moderate) RPA
Long-term^c
≤0.50	140,148	662	Referent	43	Referent	303	Referent
0.51–2.50	467,293	1923	0.98 (0.89–1.07)	115	0.83 (0.58–1.18)	886	0.95 (0.83–1.08)
2.51–4.50	376,903	1319	0.91 (0.82–1.00)	84	0.80 (0.55–1.16)	589	0.84 (0.73–0.97)
4.51–7.00	289,855	957	0.91 (0.82–1.00)	45	0.58 (0.38–0.89)	445	0.87 (0.75–1.01)
≥7.01	327,027	1021	0.90 (0.81–0.99)	61	0.73 (0.49–1.09)	478	0.87 (0.75–1.00)
P _trend			0.01		0.11		0.05
Homogeneity of trends between two subtypes					P = 0.38
Baseline^d
≤0.50	355,905	1438	Referent	98	Referent	639	Referent
0.51–2.50	457,799	1708	0.97 (0.90–1.04)	96	0.77 (0.58–1.02)	787	0.99 (0.89–1.10)
2.51–4.50	279,320	972	0.90 (0.83–0.98)	61	0.80 (0.58–1.11)	468	0.96 (0.85–1.08)
4.51–7.00	256,204	901	0.88 (0.81–0.96)	44	0.61 (0.43–0.88)	412	0.89 (0.78–1.01)
≥7.01	251,999	863	0.87 (0.80–0.95)	49	0.72 (0.50–1.02)	395	0.88 (0.77–1.00)
P _trend			<0.001		0.07		0.01
Homogeneity of trends between two subtypes					P = 0.34
Strenuous RPA^b
Long-term^c
≤0.50	449,871	2069	Referent	122	Referent	936	Referent
0.51–2.00	522,886	1 900	0.93 (0.87–0.99)	115	0.89 (0.68–1.16)	865	0.92 (0.84–1.02)
2.01–3.50	293,055	908	0.88 (0.81–0.96)	62	0.93 (0.67–1.29)	430	0.91 (0.80–1.02)
3.51–5.00	160,273	523	0.99 (0.89–1.09)	27	0.76 (0.49–1.19)	237	0.96 (0.83–1.12)
≥5.01	175,143	482	0.87 (0.78–0.97)	22	0.52 (0.31–0.87)	233	0.92 (0.78–1.08)
P _trend			0.03		0.02		0.35
Homogeneity of trends between two subtypes					P = 0.05
Baseline^d
≤50	894,810	3654	Referent	224	Referent	1675	Referent
0.51–2.00	322,058	1066	0.95 (0.89–1.02)	70	1.00 (0.76–1.32)	478	0.91 (0.82–1.01)
2.01–3.50	157,265	460	0.83 (0.75–0.92)	26	0.73 (0.48–1.11)	216	0.81 (0.70–0.94)
3.51–5.00	153,597	476	0.94 (0.85–1.04)	14	0.42 (0.24–0.73)	229	0.95 (0.83–1.10)
≥5.01	73,497	226	0.90 (0.78–1.04)	14	0.83 (0.47–1.47)	103	0.88 (0.72–1.09)
P _trend			0.01		0.01		0.06
Homogeneity of trends between two subtypes					P = 0.08
Moderate RPA^b
Long-term^c
≤0.50	321,926	1314	Referent	79	Referent	630	Referent
0.51–2.00	582,646	2134	0.99 (0.93–1.07)	134	0.99 (0.74–1.32)	954	0.90 (0.81–1.00)
2.01–3.50	330,827	1175	0.99 (0.91–1.07)	62	0.85 (0.60–1.20)	550	0.93 (0.83–1.05)
3.51–5.00	185,859	637	0.97 (0.88–1.07)	30	0.79 (0.51–1.22)	293	0.89 (0.77–1.03)
≥5.01	179,970	622	0.99 (0.89–1.10)	43	1.34 (0.89–2.02)	274	0.87 (0.74–1.01)
P _trend			0.66		0.42		0.13
Homogeneity of trends between two subtypes					P = 0.20
Baseline^d
≤0.50	519,391	1937	Referent	128	Referent	884	Referent
0.51–2.00	503,498	1788	1.00 (0.93–1.07)	99	0.82 (0.62–1.07)	808	0.98 (0.89–1.09)
2.01–3.50	233,772	891	1.04 (0.96–1.13)	51	0.93 (0.66–1.30)	438	1.11 (0.99–1.25)
3.51–5.00	226,867	799	0.91 (0.83–0.99)	43	0.83 (0.58–1.19)	366	0.90 (0.80–1.03)
≥5.01	117,700	467	0.98 (0.88–1.09)	27	0.98 (0.63–1.54)	205	0.95 (0.80–1.11)
P _trend			0.19		0.75		0.32
Homogeneity of trends between two subtypes					P = 0.98

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, combined menopausal status and MHT use variable, BMI at baseline, history of smoking, alcohol intake during the past year of baseline, screening mammogram in the past 2 years of baseline, and history of a breast biopsy
Abbreviations: BMI body mass index, CI confidence interval, ER estrogen receptor, HER2 human epidermal growth factor receptor 2, HR hazard ratio, h/wk/y hour/week/year, MHT menopausal hormone therapy, PR progesterone receptor, RPA recreational physical activity, TNBC triple negative breast cancer
^aDiagnosed in 1999 and afterward
^bAdditionally, strenuous RPA and moderate RPA mutually adjusted
^cRPA from high school till age 54 or age at cohort entry, whichever was younger
^dRPA during the 3 years prior to baseline

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