linitis plastica型胃癌の現状―病院受診群の現状

Is Linitis Plastica Type Gastric Cancer Decreasing?

要旨　近頃，linitis plastica型胃癌（LP癌）の頻度が減少しつつあるのではという見解がある．これはLP癌の早期診断に連なる胃底腺領域のⅡc型早期胃癌の診断される頻度が増加した結果ではないだろうかと考えられている．そこで，LP癌の頻度は本当に減少しているのか，そして，胃底腺領域のⅡc型早期胃癌の頻度は増加しているのかという2点について検討を加えた．対象は1982年から1991年までの10年間に3つの病院を訪れた胃癌患者2,909名（男性1,905名，女性1,004名，平均年齢62歳）である．この10年間を2年ずつに区切り，全進行癌の中でLP癌の占める割合をみると7.4％，5.8％，9.5％，8.2％，8.3％となり，LP癌の全進行胃癌に占める割合は減少を示さず，ほぼ横ばいであった．一方，胃体部のⅡc型早期胃癌の全早期胃癌の中で占める割合をみると9.6％，12.9％，13.1％，12.4％，15.9％となり増加傾向を示した．統計学的にみると，胃体部のⅡc型早期癌の割合は1982，1983年度と比べ1986，1987年度，1990，1991年度で有意に増加していた．3つの病院間で比べると，LP癌の全進行癌に占める割合は集団検診にも力を入れている病院では減少傾向を示したが，大学病院では，むしろ増加傾向を示した．これは，集団検診の場ではLP癌が減少しているのではないかということを予想させ，大学病院には化学療法を必要とする患者が集まっていることを窺わせる．一方，胃体部のⅡc型早期癌の全早期癌に占める割合は大学病院では増加していた．これは早期胃癌に関心を持ち関連する病院から症例を集めてくる結果によるものと思われた．診断技術をより進歩させ，胃底腺領域のⅡc型早期胃癌の診断に関心を持ち続けることが，近い将来，LP型胃癌を減少させることにつながる．

　Recently, it has sometimes been reported that the incidence of linitis plastica type gastric cancer (LP gastric cancer) may be decreasing, and, in fact, this is our general impression. This is thought to be ascribable to the increase in the frequency of the diagnosis of Ⅱc type early gastric cancer in the gastric fundic glandular area leading to an early diagnosis of LP gastric cancer. The following two points were examined: Is the incidence of LP gastric cancer really decreasing?; Is the incidence of Ⅱc type early gastric cancer in the fundic glandular area increasing?

　The subjects were 2,909 patients with gastric cancer who came to three hospitals during a ten-year period from 1982 to 1991, comprising 1,905 males and 1,004 females, averaging 62 years old. The ratio (calculated every second year) of LP cancer to total advanced gastric cancers during this ten-year period was 7.4% (25/337), 5.8% (19/326), 9.5% (32/337), 8.2% (26/318) and 8.3% (24/290). The above ratio showed neither statistical increase nor marked fluctuation. Next, the ratio of Ⅱc type of early cancer in the gastric fundic glandular area to total early gastric cancers was 9.6% (17/177), 12.8% (30/233), 132% (40/304), 12.4% (33/267) and 15.9% (51/320), showing at endency to increase. Statistically, the above ratio showed significant increases in 1986, 1987, 1990 and 1991 comparedwith earlier ratios in 1982 and 1983.

　Comparing statistics gathered at three hospitals, the ratio of LP cancer to the total of advanced cancers was shown to be decreasing in those hospitals involved in mass surveys, but increasing in C University hospital where patients in need of chemotherapy would naturally gather. On the other hand, the ratio of Ⅱc type of early cancers in the gastric fundic glandular area to total early gastric cancers was shown to be increasing in the same university hospital. This suggests that cases of Ⅱc type cancer would appear more frequently in a university hospital to which patients from otherhospitals would be sent, and which has a special interest in locating early gastric cancers.

　The incidence of LP gastric cancer shows neither change nor marked fluctuation, but the frequency of diagnosis of Ⅱc type early gastric cancer in the gastric fundic glandular area is increasing. The progress in diagnostic technique and continuing interest in the diagnosis of Ⅱc type early cancer in the gastric fundic glandular area will lead to a decrease in the incidence of LP cancer in the future.