Preoperative serum inhibin levels in patients with ovarian tumors

Aim: To assess the value of preoperative determination of serum inhibin levels in the prediction of malignancy in women with ovarian tumors. The prediction of malignancy not only helps patient counseling regarding prognosis and extent of surgery but also allows for proper specialist referral. Methods: Fifty women with clinically diagnosed ovarian tumors before surgery (patients group) and 32 healthy non-pregnant women in the early follicular phase of their cycle (controls) were studied. Serum inhibin (total) levels and CA125 were determined using immunoenzymometric assay and enzyme immunoassay, respectively. Results: In the patients group, 31 women had malignant ovarian tumors and 19 had benign tumors. Mean (SEM) serum inhibin levels were 0.94 (0.13) U /mL in the control group, 0.91 (0.7) U/mL in women with benign tumors and 1.9 (0.12) U/mL in women with malignant tumors; the differences are statistically significant (P < 0.01). Inhibin levels were significantly higher in women with late-stage malignant ovarian tumors (III and IV) than in early stages (I and II) and showed no significant difference in relation to menopausal status or the presence of ascites. Taking the 95th centile inhibin level in the control group (1.155 U/mL) as a discriminator level, all women with benign tumors were negative while 67.7% of women with malignant tumors were positive. The inhibin level testing predicted malignancy with a sensitivity of 67.7%, 100% specificity, 100% positive predictive value and 65.52% negative predictive value. Combining CA125 levels (>35 U/mL) with serum inhibin levels (> 1.155 U/mL) improves sensitivity of predicting malignancy to 83.87% and negative predictive value to 75% while maintaining a specificity of 100% and a positive predictive value of 100%. Combining serum inhibin with sonography achieves 96.77% sensitivity and 73.68% specificity for detecting malignancy. Conclusion: Preoperative serum inhibin levels in women with ovarian tumors are useful in the prediction of malignancy especially when combined with sonography.