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SAN FRANCISCO -- Septated ovarian tumors have a low risk of malignancy and can be followed safely with ultrasound, data from a large prospective cohort study showed.

During a median follow-up of more than five years, one patient of 1,191 with persisting septated ovarian tumors developed ovarian cancer, and that lesion arose in the contralateral ovary.

Among 30,000 patients involved in the screening study, surgery led to removal of about 500 ovarian lesions, more than 90% of which proved to benign.

"The risk of malignancy in complex ovarian tumors with septations but without solid areas or papillary projections is extremely low," Brook Saunders, MD, of the University of Tennessee in Knoxville, said here at the Society of Gynecologic Oncologists meeting.

"Patients with these tumors can be followed sonographically without surgery."

Among gynecologic malignancies, ovarian cancer has the highest mortality, and in most cases, diagnosis occurs in late stages. Earlier diagnosis could have a major impact on morbidity and mortality associated with ovarian cancer, but clinical signs and symptoms do no appear until late.

Transvaginal ultrasound (TVS) has been evaluated as a means of achieving earlier diagnosis and distinguishing between benign and malignant lesions.

Saunders and colleagues recently reported that the combination of TVS and symptoms had poor sensitivity for detecting malignancies, but had a 98% specificity, reflecting accuracy for detecting benign ovarian lesions (Cancer 2009; 115: 3606-08).

So the researchers extended the assessment of TVS to septated cystic ovarian tumors, believed to have greater malignant potential than simple cysts. To that end, they analyzed records from a database at the University of Kentucky in Lexington, where a TVS screening program has enrolled 30,000 since 1987.

Participants in the screening program have annual TVS. For women who have persisting septated ovarian tumors, the screening interval is shortened to every four to six months.

Saunders reported findings for 1,319 patients who had 2,870 complex cystic ovarian tumors with septations detected by TVS. Subsequently, 1,114 (39%) of the tumors resolved spontaneously, and 1,756 (61%) persisted. He said that 1,191 women with persistent tumors agreed to defer surgery and continue follow-up with TVS.

One patient developed a papillary projection in the contralateral ovary 3.2 years after diagnosis of a septated cystic lesion. Histologic evaluation showed the contralateral lesion to be ovarian adenocarcinoma. The remaining 1,190 patients remained free of cancer during 7,642 patient/years of follow-up.

In the total screened population, 492 ovarian tumors have been removed surgically, and 62 of those proved to be malignancies or tumors with borderline malignancy characteristics.

The remaining 430 tumors were benign, resulting in a positive predictive value of 12.6%, increasing to 22.3% if unilocular cystic and septated tumors were not removed but followed with TVS.

The Kentucky screening program has been instrumental in changing the clinical management of incidentally found adnexal masses, Susan C. Modesitt, MD, of the University of Virginia in Charlottesville, said during an invited discussion of Saunders' presentation.

Its findings contributed to the introduction of the morphology index in the 1990s, confirmed the benign nature of simple postmenopausal cysts, and led to elimination of septations as an independent prognostic factor in the morphology index.

The latest data from the screening program confirm the benign nature of isolated septated tumors, said Modesitt.

Saunders' data also showed that a malignancy was detected for every eight tumors that were surgically removed, a much lower ratio than seen in other large cohort studies.

Those notably included the NCI-sponsored Prostate, Lung, Colorectal, and Ovarian (PLCO) screening trial, which had a ratio of 19.5:1. Modesitt asked whether investigators in the screening program had an explanation for the surgical efficiency.

Saunders pointed out that the PLCO was a multicenter study, involving different surgeons, radiologists, and ultrasound technicians, all of whom could have contributed to the higher ratio.

"As you mentioned, the morphology index was developed at the University of Kentucky, so I think we're more comfortable following certain tumors that other surgeons would remove," said Saunders.

In response to another question from Modesitt, Saunders said surgeons in the Kentucky program do not have any specific thresholds for recommending removal of a tumor from an asymptomatic woman.

"It's just a clinical thing that will require taking into consideration how comfortable [surgeons] are following these, how comfortable is the patient allowing you to follow her," said Saunders. "Some of the newer tests coming out may play into that as well."

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