Omentectomy for gynecologic cancer: how much sampling is adequate for microscopic examination?

CONTEXT: Detecting omental metastasis is crucial for staging and treatment of endometrial and ovarian carcinoma.
OBJECTIVE: To determine the optimal omental sampling for omentectomies to ascertain the stage of the disease in a cost-effective way.
DESIGN: We reevaluated 258 omentectomies that were performed due to ovarian or endometrial carcinoma. A total of 116 cases were retrospectively studied, and 142 cases were prospectively studied. For prospective study, 10 to 16 blocks were sampled if the omentum showed no signs of gross tumor. Mean omental block sample frequency of 2 groups with the negative macroscopy but with or without microscopic tumor have been compared using an independent samples t test.
RESULTS: Seven patients had no evidence of tumor metastasis on gross examination but had microscopic tumor metastasis. The mean numbers of blocks were 6.4 for patients having microscopic tumor without macroscopic involvement and 7.8 for patients having neither microscopic nor macroscopic involvement. Approximately twice as many samples were taken in the prospective analysis when compared with retrospective analysis. Two cases with microscopic omental metastasis that had no macroscopic involvement at first impression were reevaluated retrospectively and found to contain 0.3- to 0.5-cm white nodules. The rate of omental metastasis increased with the grade of the tumor (P = .005).
CONCLUSION: Careful macroscopic examination is the most important step in detecting small omental metastasis. For cases with gross tumor, one section is sufficient. If a macroscopic lesion is not detectable and the patient has a high-grade tumor that will necessitate an adjuvant therapy, 3 to 5 samples seem sufficient for staging. Further studies are needed to determine the optimum sample size for tumors having a low risk of metastasis.