CA-125と経膣エコーによるスクリーニング法は有効ではない（Abstract No. 5001）

CA-125と経膣エコーを用いたスクリーニングは卵巣がん死亡率を減少させず偽陽性率を上昇させる結果になる

Screening with CA-125 and transvaginal ultrasound does not reduce ovarian cancer death rate, results in more false positives

80,000人近くの女性を対象とした無作為化多施設スクリーニングスタディの結果、卵巣がん早期発見目的の血中CA-125検査と経膣エコーの併用は卵巣がん死亡率を減少させず、多数の偽陽性およびそれに基づく生検例さらにフォローアップ検査を産出する結果となることが第47回ASCOで発表され、JAMA 6月8日号に掲載される。55～74歳の女性を年1回のスクリーニング（39,105人）または通常の管理（39,111人）を受ける群に無作為に割り付けた。スクリーニング群の女性は年1回のCA-125検査および経膣エコー検査（それぞれ6年間と4年間）を受け、13年間追跡調査された。通常管理群の女性はこれらのスクリーニング検査は要求されなかった。これらの2群間において卵巣がん発現率または死亡率に統計学的有意差は認められなかった。しかし、スクリーニング群女性においては、真陽性が212例であったのに対し、多くの偽陽性－3,285例が認められた。偽陽性であった女性において1,080人が生検のために手術を施行された；うち163人において重篤な合併症が発生した。筆者らは、これらの検査はすでに卵巣がんと診断された患者においては適切に使用されているが、一般の人々におけるスクリーニング法としては有用ではないと結論付けている。

A randomized, multicenter screening study of nearly 80,000 women in the general population showed that using a CA-125 blood test and transvaginal ultrasound for early detection of ovarian cancer did not reduce the risk of dying from the disease, and resulted in a large number of false positives and related biopsies and follow-up procedures. The results indicate that while these tests are widely and appropriately used to evaluate symptoms, and to gauge disease status and effectiveness of treatment in women already diagnosed with ovarian cancer, they are not useful in screening the general population.

"There hasn't been a good method for the early detection of ovarian cancer, and our hypothesis was that CA-125 and transvaginal ultrasound, which are useful in measuring disease, would also identify ovarian cancer early, at a stage in which it is more likely to be cured," said lead author Saundra Buys, M.D., professor of medicine at the University of Utah and Huntsman Cancer Institute in Salt Lake City. "The results were disappointing, but not necessarily surprising. The study shows that the available tests are not effective and may actually cause harm because of the high number of false positives. These results point to the continued need for more precise and effective screening tools for this disease."

In the Prostate, Lung, Colorectal and Ovarian Cancer Screening Trial, 78,216 women ages 55 to 74 were assigned to either annual screening (39,105 women) or usual care (39,111 women) between 1993 and 2001. Women in the screening arm were offered annual CA-125 testing for six years and transvaginal ultrasound for four, and followed for up to 13 years. Those in the usual care arm were not offered the screening tests.

The results showed no statistically significant difference in ovarian cancer cases or mortality between the two arms. Ovarian cancer was diagnosed in 212 women in the screening group arm compared to 176 in the usual care arm; 118 women in the screening arm died from ovarian cancer, while 100 died from ovarian cancer in the usual care group.

Among women in the screening arm, there were a high number of false positives - 3,285 false positives, compared to just 212 true positives. Of women who had a false positive test, 1,080 underwent surgery for biopsy - the procedure generally required to evaluate positive test results; 163 of them had serious complications.

The authors emphasized that the study results don't apply to screening women with symptoms or abnormal findings on physical examination. Physical examination based on symptoms and appropriate follow-up testing remains the best available approach for ovarian cancer detection.