Ovarian cancer is the eighth most common malignancy in females and the third most common gynaecological malignancy in the world. It is the leading cause of gynaecological cancer death in the world. Obesity, which is increasing worldwide, is still a controversial risk factor for ovarian cancer and till now there is no consensus on the obesity role on ovarian cancer. Therefore, we investigated the association between obesity and ovarian cancer using a large inpatient database.
We used the National Inpatient Sample (NIS) database to review female admissions between 2002 and 2015. Patients were grouped based on the presence or absence of obesity using the appropriate ICD-9 codes. We used a multivariate logistic regression to assess the association between obesity and ovarian cancer.
We reviewed 50,469,770 admissions of which 4,365,971 (8.7%) were obese. Both groups had a similar median age (54 years) but obese patients were more likely to be black (20% vs. 14%, P<.001), have polycystic ovarian syndrome (PCOS) (0.5% vs 0.1%, P<.001), endometriosis (0.9% vs. 0.7%, P<.001) and be smokers (12% vs 9%, P<.001). Family history of ovarian cancer was similar in both groups. After adjusting for age, BRCA1/BRCA2 mutations, family history, lynch syndrome, smoking, IUD, endometriosis, PCOS, infertility, oral contraceptive pills, and hormone replacement therapy, obese patients were significantly less likely to have ovarian cancer (OR=0.821, 95%CI[0.808-0.835], P< .001) compared with patients without obesity. To further assess the association between obesity and ovarian cancer in pre-menopause vs post-menopause, we did a subgroup analysis based on age, the same trend was observed in both patients younger and older than 50 years.
In our large database study, we found that obesity was associated with lower rate of ovarian cancer and that association was seen in both young and older patients. However, the timeliness of obesity in relation to ovarian cancer cannot be determined through the NIS database and thus further prospective epidemiological studies are warranted.
The authors.
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All authors have declared no conflicts of interest.