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Ovarian Cancer Health Center

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Description of the Evidence

continued...

Manual pelvic examination is a part of the routine pelvic examination. The sensitivity and specificity of the pelvic examination are not characterized, but examination generally detects advanced disease.[6,7] There is no evidence for the benefit of this test for the early detection of and decreased mortality from ovarian cancer and it is not further considered.

The focus in this summary is on asymptomatic screening for ovarian cancer. Ovarian cancer often presents with persistent but vague symptoms and some investigators have proposed the use of symptom indices as a method for screening for ovarian cancer.[8,9] Because this is not, by definition, asymptomatic screening, it is not considered further in this summary.

Transvaginal ultrasonography (or transvaginal sonography)

TVU (or transvaginal sonogram [TVS]) has been proposed as a screening method for ovarian cancer because of its ability to reliably measure ovarian size and detect small masses.[10]

TVU as an independent screening modality is being evaluated in one arm of the United Kingdom Collaborative Trial of Ovarian Cancer Screening (UKCTOCS) (NCT00058032).[11] The UKTOCS is an ongoing randomized controlled trial of 202,638 postmenopausal women recruited in 13 trial centers across the United Kingdom. Women were randomly assigned to receive multimodality screening with CA-125 as a primary test and TVS as a secondary screen (multimodal group); an ultrasound only (ultrasound group); or no routine screening (control group). Of the 50,639 women randomly assigned to receive ultrasound screening, 48,230 attended the first year screening, with 48,053 women with data to evaluate ovarian morphology. Of these, 9.1% (4,367) had an abnormal adnexal scan. Among women with an abnormal scan, the absolute risk of epithelial ovarian cancer in the next 3 years was 1.08%. Thus, most of these abnormal scans represented a false-positive test result. In the ultrasound group, 11,982 women had both ovaries visualized and normal scans at all UKCTOCS annual visits during the 3-year study period. Among this group, eight women were diagnosed with epithelial ovarian cancer within 3 years of the first scan.

The UKCTOCS published sensitivity and specificity results from their prevalent screen. The ultrasound screening arm had several levels of screening and possible referral strategies: an abnormal scan resulted in a repeat scan in 6 to 8 weeks, and if still abnormal, a referral was made for clinical assessment. Of 53 total cancers (screen-detected and interval cancers in the following year), 45 were screen positive by ultrasound (two abnormal scans) for a sensitivity of 84.9%. For invasive cancer, the sensitivity was 75%. Specificity of the ultrasound screening arm was calculated to be 98.2%.[12]

CA-125 concentrations

CA-125 is a tumor-associated antigen that is used clinically to monitor patients with epithelial ovarian carcinomas.[13,14] Measurement of CA-125 concentrations has been proposed as a potential marker for the early detection of ovarian cancer, either as a single test with a threshold cutpoint or in algorithms examining the change in levels over time. The two randomized trials have included CA-125 either in parallel or sequentially with TVU for multimodality screening. The most commonly reported CA-125 reference value that designates a positive screening test is 35 U/mL, and this was the reference value used in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Screening Trial (NCT00002540) to define an abnormal test result. The measurement of CA-125 levels, in parallel combination with TVU,[15] is the ovarian screening intervention evaluated in the PLCO.[16,17] Elevated CA-125 levels are not specific to ovarian cancer and have been observed in patients with nongynecological cancers [14] and in the presence of other conditions such as the first trimester of pregnancy [18,19] or endometriosis.[20] The sensitivity of the CA-125 test for the detection of ovarian cancer was estimated in two nested case-control studies using serum banks.[21,22] The sensitivity for CA-125 levels of at least 35 U/mL ranged from 20% to 57% for cases occurring within the first 3 years of follow-up; the specificity was 95%.

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