Table 3 Incidence rate (IR, per 100,000 person-years) and hazard ratio (HR) with 95% confidence interval (CI) of any cancer in relation to surgical removal of tonsils and adenoids, analysis by characteristics of the surgery, a population-based and sibling-controlled cohort study (3-year lag time)*

Type of surgery

 No surgery

579,451/358.0

Ref

17,735/228.2

Ref

 Tonsillectomy

8575/296.0

1.09 (1.07–1.11)

6016/292.6

1.14 (1.09–1.20)

 Adenotonsillectomy

409/155.9

1.17 (1.05–1.28)

308/163.3

1.05 (0.85–1.31)

 Adenoidectomy

890/138.3

1.10 (1.03–1.17)

662/143.7

1.15 (0.99–1.33)

 P for difference

0.28

0.71

Age at surgery

 No surgery

579,451/358.0

Ref

17,735/228.2

Ref

 1–6

30/56.1

1.13 (0.79–1.62)

18/56.2

0.96 (0.29–3.12)

 7–12

302/72.8

1.13 (1.00–1.29)

209/77.5

1.50 (0.94–2.40)

 13–18

777/112.1

1.02 (0.94–1.11)

545/115.4

1.21 (0.92–1.58)

 19–45

7501/305.5

1.08 (1.05–1.10)

5316/302.6

1.12 (1.06–1.19)

 46–

1168/1114.6

1.07 (0.97–1.17)

760/1102.3

1.06 (0.61–1.84)

 P for difference

0.63

0.57

Potential indications for surgery

 No surgery

579,451/358.0

Ref

17,735/228.2

Ref

 Hypertrophy of tonsils and adenoids

5512/242.6

1.08 (1.05–1.12)

3853/245.2

1.19 (1.11–1.17)

 Chronic tonsilitis, pharyngitis and nasopharyngitis, or peritonsillar abscess

2718/255.7

1.09 (1.07–1.12)

1947/255.8

1.12 (1.06–1.18)

 Sleep disorders or dyspnea and  respiratory abnormalities

78/600.8

1.09 (1.07–1.12)

58/629.6

1.14 (1.09–1.20)

 Other diseases of tonsils and adenoids

173/113.3

1.10 (1.07–1.12)

121/152.2

1.15 (1.10–1.20)

 P for difference

0.74

0.36

Time since surgery

 No surgery

579,451/358.0

Ref

17,735/228.2

Ref

 > 3–10 years

994/100.0

1.06 (0.92–1.21)

676/97.1

1.25 (0.89–1.76)

 11–20 years

2281/178.6

1.14 (1.07–1.23)

1615/180.6

1.19 (1.01–1.41)

 21– years

6503/449.0

1.09 (1.06–1.12)

4557/451.5

1.12 (1.06–1.18)

 P for trend

0.27

0.001