Table 4.

Hazard ratios and 95% confidence intervals for the association between latent classes and breast cancer risk among postmenopausal and premenopausal white women at time of breast cancer diagnosis.

Exposure	Premenopausal				Postmenopausal				Interaction p-Valued
	Person-years	BC eventsa	HR (95% CI)b	adjHR (95% CI)c	Person-years	BC eventsa	HR (95% CI)b	adjHR (95% CI)c
Beauty Classes
Infrequent user	6,834	74	1	1	53,247	372	1	1
Moderate user	19,586	177	0.99 (0.75, 1.30)	0.98 (0.74, 1.30)	84,289	631	1.13 (1.10, 1.16)	1.16 (1.12, 1.19)	0.26
Frequent user	19,861	191	1.01 (0.77, 1.33)	1.01 (0.76, 1.33)	90,181	656	1.14 (1.10, 1.17)	1.18 (1.14, 1.21)	0.33
Totalse	46,281	442			227,717	1,659
Hair Classes
Infrequent users of hair spray	21,377	208	1	1	115,014	841	1	1
Moderate users of hair spray, conditioner, pomade and hair straightener	443	4	—	—	7,190	56	0.76 (0.71, 0.81)	0.76 (0.71, 0.81)	0.46
Frequent users of hair spray and hair gel	24,277	229	1.07 (0.89, 1.29)	1.04 (0.86, 1.26)	103,825	757	1.01 (0.99, 1.03)	1.03 (1.01, 1.06)	0.84
Totalse	46,097	441			226,029	1,654
Skincare Classes
Infrequent user	8,266	76	1	1	43,793	324	1	1
Moderate user	20,031	200	1.09 (0.84, 1.42)	1.06 (0.81, 1.39)	101,807	721	1.05 (1.02, 1.08)	1.08 (1.05, 1.12)	0.51
Frequent user	13,152	122	1.07 (0.80, 1.42)	1.06 (0.79, 1.42)	52,621	420	1.11 (1.07, 1.14)	1.12 (1.09, 1.16)	0.65
Talcum powder user	4,853	44	0.88 (0.61, 1.29)	0.84 (0.57, 1.23)	29,453	195	0.99 (0.95, 1.03)	1.03 (0.99, 1.07)	0.91
Totalse	46,302	442			227,674	1,660

Note: adjHR, adjusted hazard ratio; BC, breast cancer; CI, confidence interval; HR, hazard ratio.

^aTotal numbers of BC events and person-years are for women with complete data for each product class; after accounting for missing data, among women with known menopausal status, total numbers of person-years and BC events were 47,166 and 445, respectively, for premenopausal white women and 230,023 and 1,679, respectively, for postmenopausal white women; results were not reported if $<20\text{BC}$ events.

^bModels accounted for age by using age as the time scale, where participants entered the analysis at their enrollment age (left-truncation) and accrued person-time until they exited at their cancer diagnosis or were administratively censored at their age at last follow-up.

^cIn addition to the adjustments described in ^b, models were adjusted for baseline menopausal status, parity, age at first live birth, duration of breastfeeding, adult body mass index, alcohol use, oral contraceptive use, hormone therapy use, education, family history, region of residence, age at menarche, and smoking status. Results were not reported if $<20\text{BC}$ events.

^dp-Value for interaction by menopausal status, derived by adding interaction term to adjusted Cox proportional hazard model for pre- and postmenopausal white women.

^eWomen with unknown or missing menopausal status at follow-up ($n=346$) were excluded; $n=22$ breast cancer cases were premenopausal at baseline and had an unknown menopausal status at follow-up.