卵巣がんの有望な新スクリーニング法

平均的リスクの閉経後女性を対象とした有望な卵巣がん新スクリーニング法が開発された
Promising new ovarian cancer screening strategy developed for post-menopausal women at average risk
血中CA-125検査結果の傾向と患者の年齢を組み合わせた数理的モデルを使用し、その後経膣エコーを行い必要があれば婦人科オンコロジストに委託するといった、平均的卵巣がんリスクの閉経後女性を対象とした有望な新スクリーニング法は、現実的で偽陽性率も非常に低いことが示された。研究者らは、患者の年齢および経時的な血中CA-125レベルの傾向に基づく“卵巣がんリスクアルゴリズム”（ROCA）を評価した。CA-125レベルが上昇していた女性にはその後経膣エコー（TVS）を施行し、必要に応じて手術の必要性の有無に関する評価を婦人科オンコロジストに委託した。このスタディでは乳がんおよび卵巣がんの有意な家族歴のない50～74歳の閉経後女性3,238人を対象とし8年間追跡調査した。TVSが必要な女性は年間1%未満であった。8人の女性がROCAの結果に基づき手術を施行され、そのうち3人は浸潤性であるが早期のがんであった。ROCAの後にTVSを施行し手術の是非を委託する方法の特異度は99.7%であり、この方法による偽陽性率は非常に低いことが示された。これらの結果は第46回ASCOで発表された。
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Researchers have tested a promising new screening approach for post-menopausal women at average risk of ovarian cancer. The strategy uses a mathematical model that combines trends in CA-125 blood test results and a patient's age, followed by transvaginal ultrasound and referral to a gynecologic oncologist, if necessary. The researchers found that this approach is feasible and produces very few false-positive results.

"More than 70 percent of ovarian cancers are diagnosed when they have already grown to an advanced stage, so identifying a reliable screening test for early-stage disease would be like finding the Holy Grail," said lead author Karen Lu, M.D., professor of gynecologic oncology at The University of Texas M.D. Anderson Cancer Center. "This study is one step forward in that direction. If confirmed in larger studies, this approach could be a useful and relatively inexpensive tool for detecting ovarian cancer in its early, more curable stages, including the types of ovarian cancer that biologically are the most aggressive."

While women at high risk of ovarian cancer may undergo more frequent screening or take other measures to reduce their risk, there are currently no screening tools for women at average risk of this disease. CA-125 is a protein that has been known for years to rise during ovarian cancer development, but because it can become elevated in response to other factors, it is not specific for ovarian cancer.

In this study, the researchers evaluated a "Risk of Ovarian Cancer Algorithm" (ROCA) -- which is based on a patient's age and trends in CA-125 blood test results over time -- followed by transvaginal sonography (TVS) in women with rising CA-125 levels, and, when needed, referral to a gynecologic oncologist to determine if surgery was necessary.

The study included 3,238 postmenopausal women aged 50 to 74 with no significant family history of breast or ovarian cancer who were followed for up to eight years. Ovarian cancer most commonly occurs in women over 50, and CA-125 is a more sensitive marker of ovarian cancer in postmenopausal than premenopausal women.

On an annual basis, less than 1 percent of the women required TVS. Eight women underwent surgery based on the ROCA results, three of whom had invasive but early-stage ovarian cancers (two had borderline ovarian tumors and three had benign ovarian tumors). The specificity of ROCA followed by TVS for referral to surgery was 99.7 percent, indicating that very few false-positives resulted from this approach.

A large-scale study of ROCA is under way in the United Kingdom in more than 200,000 women; the results are expected in 2015. If the algorithm is validated, CA-125 testing could be recommended as part of a woman's annual check-up with a physician.

This study was presented at ASCO's 46th Annual Meeting in Chicago.

Disclosures: Herbert Fritsche, Research Funding, Roche Diagnostics; Robert Bast, Consultant or Advisory Role, Fujiresio Diagnostics Inc., Other Remuneration, Royalties for CA125.