Clinical trial of Japan Polyp Study (JPS)

The Japan polyp study (JPS) is a large randomised controlled trial conducted in Japan.
The Director was working at the National Cancer Centre Central Hospital when the study started in 2000 and was the first head of the JPS research group.
The aim of the JPS was a study to determine whether the appropriate interval between colonoscopy is one year or three years after all polyps have been removed (clean colon) by colonoscopy, the next examination. The study is subject of aged 40-69 years. All polyps are removed at the first colonoscopy (First TCS). To check for missed cancers, all patients undergo a colonoscopy (second TCS) after one year. They are then randomly allocated to a two-examination group at one and three year or a one-examination group at three year only. The cumulative AN detection rate for both groups was then used to colonoscopy whether the appropriate colonoscopy interval was after one year or three year.

* TCS: Total colonoscopy
* AN(Advanced neoplasia): Adenomas >10 mm, High grade adenoma, carcinoma

The results of the JPS study were published in the international medical journal "GUT" in 2020.
The cumulative frequency of detection of Advanced Neoplasia (AN) was 1.7% in the two-examination group (1 and 3 years) and 2.1% in the one-examination group (3 years only) after all polyps were removed (clean colon), with no significant difference between the two groups. As a result, after removing all polyps with two TCS, the next TCS proved to be after three years, which is the appropriate period.
Furthermore, it was also found that many missed cancers are flat cancers that are difficult to detect.

* AN(Advanced neoplasia): Adenomas >10 mm, High grade adenoma, carcinoma