Hysterectomy and subsequent risk of cancer.
BACKGROUND
The objective of this retrospective cohort study was to assess the effect of hysterectomy on subsequent risk of cancer among 25,382 hysterectomized and a similar number of non-hysterectomized control women, registered in 1963-1976 in the Mass Screening Registry (MSR).


METHODS
Cancer cases were obtained from the Finnish Cancer Registry (FCR) and standardized incidence ratio (SIR); the expected number of cases based on cancer incidence rates of the Finnish female population in 1967-1993, was used. Relative risk (RR) was calculated as SIR among the hysterectomized relative to non-hysterectomized women, adjusted for follow-up, education and parity.


RESULTS
The RR estimates of non-genital cancers among women with any hysterectomy were approximately 5% higher than in the non-hysterectomized cohort. Relative risks of rectal cancer (RR = 1.4, 95% confidence interval [CI]: 1.0-1.8) and thyroid cancer (RR = 2.1, 95% CI; 1.5-3.1) were significant and largest among women who had undergone total hysterectomy pre- or perimenopausally. Relative risk estimates of breast cancer were close to unity.


CONCLUSIONS
Hysterectomy is not associated with any substantial protective or promoting effect on cancers in general. Elevated risk of papillary thyroid cancer following hysterectomy is biologically plausible, as there are reproductive and endocrinological causes of thyroid cancer.
Luoto
R
R
National Public Health Institute, Department of Epidemiology and Health Promotion, Helsinki, Finland.
Auvinen
A
A
Pukkala
E
E
Hakama
M
M
D000328:Adult; D000367:Age Factors; D016009:Chi-Square Distribution; D015331:Cohort Studies; D016001:Confidence Intervals; D005260:Female; D005387:Finland / Q000453:epidemiology; D005833:Genital Neoplasms, Female / Q000453:epidemiology; D006801:Humans; D007044:Hysterectomy / Q000009:adverse effects / Q000706:statistics & numerical data*; D008875:Middle Aged; D009369:Neoplasms / Q000453:epidemiology*; D012004:Rectal Neoplasms / Q000453:epidemiology; D012042:Registries; D012189:Retrospective Studies; D012306:Risk; D013964:Thyroid Neoplasms / Q000453:epidemiology; D013997:Time Factors