マンモグラフィーのスクリーニング間隔は乳がんの予後に影響を与える可能性がある （Abstract: SST01-01）

スクリーニングのマンモグラフィーを頻回に受けていた患者ほどリンパ節転移陽性率が有意に低かった
Patients who had screening mammograms more often had a significantly lower rate of lymph node positivity
スクリーニングマンモグラフィーにより検出された乳がん患者を対象としたスタディにおいて、スクリーニングマンモグラフィーをより頻回に受けていた患者はスクリーニング検査間隔が長期であった患者よりもリンパ節転移陽性率が有意に低かったとの結果であった、と2013年Radiological Society of North America年次集会で発表された。この後ろ向きスタディは、スクリーニングマンモグラフィーで乳がんを発見された女性332人を対象とし、スクリーニングマンモグラフィーの間隔に基づき3群（1.5年未満、1.5～3年、3年以上）のうちの１つに割り付けられた。女性の数はそれぞれ207、73および52人であった。年齢、乳房密度、高リスク状況および乳がん家族歴などで補正した結果、スクリーニングの間隔が1.5年未満の女性はリンパ節転移陽性率が8.7%と最低であった。リンパ節転移陽性率は1.5～3年および3年以上の群でそれぞれ20.5%および15.4%で有意に高かった。これらの結果に基づき筆者らは、女性らは40歳時にスクリーニングマンモグラフィーを開始し、2年に1度ではなく毎年受けるべきであると述べている。
Full Text

In a study of screening mammography-detected breast cancers, patients who had more frequent screening mammography had a significantly lower rate of lymph node positivity as compared to women who went longer intervals between screening mammography exams. Results of the study were presented at the 2013 annual meeting of the Radiological Society of North America (RSNA).

"On its pathway to other places in the body, the first place breast cancer typically drains into before metastasizing is the lymph nodes," said Lilian Wang, M.D., assistant professor of radiology at Northwestern University/Feinberg School of Medicine in Chicago, Ill. "When breast cancer has spread into the lymph nodes, the patient is often treated both locally and systemically, with either hormone therapy, chemotherapy, trastuzumab or some combination of these therapies."

Historically, healthcare organizations, such as RSNA and the American Cancer Society (ACS), have recommended annual screening with mammography for women beginning at age 40. However, in 2009, the United States Preventive Services Task Force (USPSTF) announced a controversial new recommendation for biennial screening for women between the ages of 50 and 74.

"Our study looks at what would happen if the revised guidelines issued by USPSTF were followed by women," Dr. Wang said.

The retrospective study, conducted at Northwestern Memorial Hospital, included 332 women with breast cancer identified by screening mammography between 2007 and 2010. The women were divided into one of three groups, based on the length of time between their screening mammography exams: less than 1.5 years, 1.5 to three years and more than three years. There were 207, 73 and 52 patients in each category, respectively.

Controlling for age, breast density, high-risk status and a family history of breast cancer, the researchers determined that women in the less than 1.5-year interval group had the lowest lymph node positivity rate at 8.7 percent. The rate of lymph node involvement was significantly higher in the 1.5- to three-year and over three-year interval groups at 20.5 percent and 15.4 percent, respectively.

"Our study shows that screening mammography performed at an interval of less than 1.5 years reduces the rate of lymph node positivity, thereby improving patient prognosis," Dr. Wang said. "We should be following the guidelines of the American Cancer Society and other organizations, recommending that women undergo annual screening mammography beginning at age 40."

Co-authors are Ellen B. Mendelson, M.D., Paula M. Grabler, M.D., Riti Mahadevia, B.A., and Laura Billadello, M.D.