Diagnosis of endometrial cancer in patients with postmenopausal bleeding by analysis of the lactate dehydrogenase isoenzyme activity profile in uterine fluid.

OBJECTIVE

We have previously shown that high activity of lactate dehydrogenase (LD) isoenzymes 4 and 5 in terine aspirates is a marker for endometrial carcinoma. The purpose of this study was to identify an abnormal activity profile of LD2-5 using LD1 as an internal standard, thereby being able to dispense with measurement of the total LD activity. The profile was subsequently tested for diagnostic power in clinical settings.

METHODS

We used data from 11 cases of endometrial cancer. Each isoenzyme was estimated relative to the activity of LD1 (LD1 = 1.0). Based on the lowest level found for each of LD2-5 in the 11 cases, the cut-off levels for an "abnormal profile" were identified. The abnormal profile was subsequently tested for diagnostic power in a group of postmenopausal women at risk for endometrial cancer, that is, they had experienced vaginal bleeding (n = 100). A second group of asymptomatic postmenopausal women (n = 366) had endouterine aspiration performed as part of a regular gynecologic check up to evaluate the prevalence of an abnormal LD isoenzyme profile.

RESULTS

In the group of postmenopausal women who had experienced vaginal bleeding, abnormal profile was found in 27 cases: 14 with adenocarcinoma and 13 with benign histology. All cases with normal profile had benign histology. Thus, sensitivity as well as the negative predictive value was 100%. In the group of asymptomatic women, abnormal LD isoenzyme profile was found in 15 cases (4.1%). All had benign histology.

CONCLUSIONS

The LD isoenzyme profile detects endometrial malignancy with high accuracy, and equally important, a normal profile excludes malignancy. The profile, which uses relative rather than absolute activity levels, based on LD1 as an internal standard, has the great advantage of being independent of both the dilution factor and the aspiration technique. Larger studies comparing the LD isoenzyme activity profile with ultrasonographic evaluation and biopsy histology are needed.