Tubal ligation, hysterectomy, unilateral oophorectomy, and risk of ovarian cancer in the Nurses' Health Studies.
OBJECTIVE
To prospectively examine whether the association between tubal ligation, hysterectomy, unilateral oophorectomy, and ovarian cancer varied by patient, tumor, and surgical characteristics.


METHODS
Two prospective cohort studies (Nurses' Health Study and Nurses' Health Study II).


METHODS
Not applicable.


METHODS
A cohort of 121,700 married US female nurses, aged 30-55 years at baseline and another cohort of 116,430 US female nurses aged 25-42 years at baseline.


METHODS
We obtained data on gynecologic surgeries and ovarian cancer incidence through biennial questionnaires. We calculated hazard ratios (HRs) and 95% confidence intervals (CIs) adjusted for known and suspected ovarian cancer risk factors.


METHODS
Confirmed incident epithelial ovarian cancer.


RESULTS
Overall, tubal ligation was associated with a decreased risk of ovarian cancer (HR, 0.76; 95% CI 0.64-0.90). The inverse association was stronger for nonserous tumors (HR, 0.57; 95% CI 0.40-0.82) and among women younger than 35 years at surgery (HR, 0.67; 95% CI 0.49-0.90). Hysterectomy was associated with a decreased risk of ovarian cancer (HR, 0.80; 95% CI 0.66-0.97) and was somewhat stronger for nonserous tumors (HR, 0.70; 95% CI 0.49-1.02). Unilateral oophorectomy was associated with a 30% lower risk (HR, 0.70; 95% CI 0.53-0.91), which did not differ by histologic subtype.


CONCLUSIONS
Our study provides further support that tubal ligation reduces the risk of ovarian cancer, particularly for nonserous tumors and when conducted before the age of 35 years. The inverse association with hysterectomy, along with the stronger associations for nonserous tumors, supports shared biologic mechanisms for tubal ligation and hysterectomy.
Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts. Electronic address: nhmsr@channing.harvard.edu.
Megan S
MS
Rice
Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts; Division of Biostatistics and Epidemiology, University of Massachusetts, Amherst, Massachusetts.
Susan E
SE
Hankinson
Channing Division of Network Medicine, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts; Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts.
Shelley S
SS
Tworoger
D000328:Adult; D000367:Age Factors; D000077216:Carcinoma, Ovarian Epithelial; D005260:Female; D006306:Health Surveys; D006801:Humans; D007044:Hysterectomy; D015994:Incidence; D008875:Middle Aged; D009375:Neoplasms, Glandular and Epithelial / Q000453:epidemiology / Q000473:pathology / Q000517:prevention & control*; D009726:Nurses; D010051:Ovarian Neoplasms / Q000453:epidemiology / Q000473:pathology / Q000517:prevention & control*; D010052:Ovariectomy; D011446:Prospective Studies; D012307:Risk Factors; D013246:Sterilization, Tubal; D011795:Surveys and Questionnaires; D013997:Time Factors; D014481:United States / Q000453:epidemiology
Tubal ligation; hysterectomy; ovarian cancer; unilateral oophorectomy