. 2024 Sep 18;132(9):097008. doi: 10.1289/EHP14065

Table 2.

PFOS, PFOA, and PFHxS levels and covariate-adjusted least square means of mammographic breast density in 700 premenopausal women who completed their annual screening mammogram at Washington University School of Medicine (St. Louis, Missouri) from December 2015 to October 2016 and from September 2020 to February 2022.

Category	Quartile 1 LSM (95% CI)	Quartile 2 LSM (95% CI)	Quartile 3 LSM (95% CI)	Quartile 4 LSM (95% CI)	$p$ -Trend
Volumetric percent density (%)
PFOS^a	8.06 (7.27, 8.93)	8.03 (7.23, 8.91)	8.48 (7.63, 9.41)	8.43 (7.58, 9.37)	0.35
PFOA^b	8.24 (7.42, 9.16)	7.76 (7.00, 8.60)	8.66 (7.81, 9.61)	8.30 (7.43, 9.26)	0.62
PFHxS^c	7.92 (7.14, 8.79)	8.51 (7.68, 9.43)	8.25 (7.41, 9.19)	8.28 (7.44, 9.22)	0.75
Nondense volume ( ${cm}^{3}$ )
PFOS^a	785.39 (710.28, 868.44)	852.42 (769.9, 943.78)	830.7 (749.78, 920.34)	839.23 (756.96, 930.45)	0.43
PFOA^b	820.92 (740.46, 910.12)	845.59 (764.45, 935.35)	794.55 (718.12, 879.11)	848.36 (761.93, 944.58)	0.59
PFHxS^c	823.66 (744.16, 911.66)	786.78 (711.99, 869.43)	815.74 (734.38, 906.12)	881.8 (794.38, 978.84)	0.07
Dense volume ( ${cm}^{3}$ )
PFOS^a	65.45 (59.19, 72.37)	70.74 (63.9, 78.32)	73.31 (66.17, 81.22)	73.52 (66.32, 81.51)	0.06
PFOA^b	69.98 (63.11, 77.60)	67.71 (61.2, 74.91)	71.71 (64.8, 79.35)	73.36 (65.87, 81.7)	0.22
PFHxS^c	67.64 (61.1, 74.89)	69.91 (63.25, 77.28)	69.06 (62.16, 76.73)	75.79 (68.26, 84.15)	0.03

Note: Multivariable linear regression models were performed to calculate adjusted least square means of MBD (VPD, NDV, DV) by quartile of PFAS (PFOS, PFOA, PFHxS), and $p$ for trend values are presented to assess significance across the quartiles. Measures of MBD were $log to the base 10$ transformed and coefficients back-transformed ( $10 begin superscript lowercase beta end superscript$ ). The $p$ -value for linear trend was computed by assigning the median of each quartile to all observations within the quartile and then treating it as an ordinal variable in the model. Five women were excluded due to missing MBD measurements. 95% CI, 95% confidence interval; DV, dense volume; LSM, least square mean; MBD, mammographic breast density; NDV, nondense volume; PFAS, per- and polyfluoroalkyl substances; PFHxS, perfluorohexane sulfonate; PFOA, perfluorooctanoic acid; PFOS, perfluorooctane sulfonate; VPD, volumetric percent density. All models were adjusted for age (continuous), age at menarche (continuous), body fat percentage (continuous), race (non-Hispanic white, non-Hispanic black, other), family history of breast cancer (yes, no), oral contraceptive use (never, $less than 1 year$ , 1–4 years, 5–9 years, $greater than 10 years$ ), alcohol consumption (never, $less than 1$ drink per week, 1–2 drinks per week, 3–5 drinks per week, and $greater than 6$ per week), parity/age at first birth (nulliparous, 1–2 children and $less than 25 years$ , 1–2 children and 25–29 years, 1–2 children and $greater than or equal to 30 years$ , $greater than or equal to 3$ children and $less than 25 years$ , $greater than or equal to 3$ children and $greater than or equal to 25 years$ ), and body shape at age 10 (1 and 2, 3 and 4, 5, 6–9). Quartile values shown are $multiplied by 10 begin superscript 6 end superscript$ .

^{^a}

Ranges for the quartiles of PFOS (minimum, maximum): Q1 (0.09, 1.84), Q2 (1.84, 2.75), Q3 (2.75, 4.24), Q4 (4.24, 31.3).

^{^b}

Ranges for the quartiles of PFOA (minimum, maximum): Q1 (0.10, 0.79), Q2 (0.79, 1.25), Q3 (1.25, 1.82), Q4 (1.82, 34.5).

^{^c}

Ranges for the quartiles of PFHxS (minimum, maximum): Q1 (0.09, 0.70), Q2 (0.70, 1.13), Q3 (1.13, 1.73), Q4 (1.73, 11.3).