Table 4 IVF exposure and breast cancer risk in subfertile BRCA1/2 mutation carriers

From: Ovarian stimulation for IVF and risk of primary breast cancer in BRCA1/2 mutation carriers

 

BC+a

BC−a

HR (95% CI)b

n = 232

93 (40.1)

139 (59.9)

 

IVF treatment

  No

79 (85.0)

100 (71.9)

1.00

  Yes

12 (12.9)

37 (26.6)

0.73 (0.39–1.37)

  Missing

2 (2.2)

2 (1.4)

 

Age at first IVF (%)c

  Median (min–max, years)

31.9 (24–37)

32.6 (24–41)

 

  No IVF

79 (85.0)

100 (71.9)

1.00

  ≤32 years

6 (6.5)

17 (12.2)

0.93 (0.40–2.17)

  >32 years

6 (6.5)

20 (14.4)

0.60 (0.25–1.41)

  Missing

2 (2.2)

2 (1.4)

 

Time since first IVF treatment (%)c

  No IVF

79 (85.0)

100 (71.9)

1.00

  <5 years ago started

6 (6.5)

11 (7.9)

0.94 (0.40–2.22)

  ≥5 years ago started

6 (6.5)

26 (18.7)

0.59 (0.25–1.40)

  Missing

2 (2.2)

2 (1.4)

 

Time since last IVF treatment (%)c

  No IVF

79 (85.0)

100 (71.9)

1.00

  <2 years ago stopped

5 (5.4)

7 (5.0)

1.05 (0.41–2.65)

  ≥2 years ago stopped

6 (6.5)

29 (20.9)

0.55 (0.23–1.31)

  Age of last treatment before censoring unknown

1 (1.1)

1 (0.7)

 

  Missing

2 (2.2)

2 (1.4)

 
  1. BC breast cancer, HR hazard ratio, CI confidence interval, IVF in vitro fertilisation.
  2. aDistribution of variable at time of censoring.
  3. bInstrinsically stratiefied on birth year (1940–1957, 1958–1968, 1969–1993).
  4. cCutoffs of categories in variables related to IVF characteristics are based on numbers of cases available in the exposed group
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