Table 2.

Effect of hormone therapy cessation on likelihood of a decrease in %MD between mammograms: RRs and ARs of a decrease in %MD of ≥7.5% versus no change (3%), overall and by reproductive and demographic subgroups

 Continued hormone therapy use (referent group)1- to 2-mo hormone therapy cessation1- to 2-mo vs. no hormone therapy cessation
No change,an (%)Decrease ≥7.5%, n (%)No change, n (%)Decrease ≥7.5%, n (%)RRb (95% CI)ARb, c (%) (95% CI)
Overall effect154 (100)66 (100)235 (100)152 (100)1.3 (1.03–1.7)9 (2–17)
Age, y
 66+39 (25)20 (30)57 (24)30 (20)1.5 (1.0–2.2)9 (−6 to 25)
 56–6574 (48)33 (50)122 (52)70 (46)1.2 (0.8–1.7)6 (−5 to 17)
 45–5541 (27)20 (30)56 (24)52 (34)1.4 (0.8–2.4)15 (0–30)
BMI,d kg/m2
 <2565 (42)32 (48)96 (41)54 (40)1.2 (0.9–1.7)7 (−5 to 19)
 25–3057 (37)18 (27)79 (34)48 (32)1.6 (1.0–2.5)14 (1–27)
 >3032 (21)16 (24)60 (26)41 (27)1.2 (0.8–1.9)7 (−9 to 24)
Baseline %MDd
 10% to <20%68 (44)5 (8)97 (41)21 (14)2.6 (1.02–6.6)11 (2–20)
 20% to <30%40 (26)14 (21)72 (31)34 (22)1.2 (0.7–2.1)6 (−9 to 21)
 30% to <40%23 (15)22 (33)40 (17)43 (28)1.1 (0.7–1.5)3 (−15 to 21)
 40+%23 (15)25 (38)26 (11)54 (36)1.3 (0.9–1.8)15 (−2 to 33)
Parity
 Parous125 (81)56 (85)185 (79)121 (80)1.3 (1.0–1.7)9 (0–17)
 Nulliparous29 (19)10 (15)50 (21)31 (20)1.5 (0.8–2.7)13 (−5 to 30)
Family history of breast cancer (first degree)
 Yes28 (18)11 (17)45 (19)25 (16)1.3 (0.7–2.3)10 (1–19)
 No120 (78)52 (79)185 (79)125 (82)1.3 (1.0–1.7)8 (−11 to 26)
Change in BMI
 Decrease >1.511 (7)4 (6)24 (10)10 (7)1.1 (0.4–3.0)3 (−24 to 30)
 No change (≤1.5)99 (64)46 (70)145 (62)100 (66)1.3 (1.0–1.7)9 (0–19)
 Increase >1.533 (21)14 (21)53 (23)35 (23)1.3 (0.8–2.2)10 (−7 to 27)
Hormone therapy type
 Estrogen therapy92 (60)42 (64)149 (63)84 (55)1.2 (0.8–1.6)5 (−5 to 15)
 Estrogen + progesterone62 (40)24 (36)86 (37)68 (45)1.6 (1.1–2.3)16 (4–29)
Hormone therapy duration,e y
 <521 (14)9 (14)21 (9)27 (18)1.9 (1.0–3.4)26 (5–48)
 5–933 (21)17 (26)55 (23)37 (24)1.2 (0.7–1.9)6 (−10 to 23)
 10–1424 (16)12 (18)54 (23)28 (18)1.0 (0.6–1.8)1 (−18 to 19)
 15+66 (43)25 (38)91 (39)55 (36)1.4 (0.9–2.0)10 (2–22)
  • aPercentages may not add to 100 because of rounding to the nearest 1%.

  • bUnadjusted (assignment to the exposure was randomized and is not associated with other factors; ref. 5).

  • cAR: cumulative incidence (proportion) of women in the cessation group who experienced a decrease in MD of ≥7.5% due to hormone therapy cessation.

  • dAt index mammogram.

  • eDuration of prior hormone therapy use at baseline.