Abstract
Japan’s colorectal cancer age-adjusted mortality rate has been decreasing for over 10 years, but it has been decreasing in the US and UK for even longer, and their rates are now lower than Japan’s. The number of deaths from colorectal cancer continues to grow in Japan and decrease in the US. In 2015 it was the same in Japan and the US, which has 2.5 times Japan’s population. The US decrease is attributable to a high colonoscopy rate (approximately 60% every 10 years). Screening in Japan and the EU is performed through fecal occult blood tests.
This method (chemical method) has proven effective in RCT, but interval cancers are discovered through subjective symptoms, etc., despite testing negative. We checked the cancer registry records of colorectal cancer screening recipients in Fukui Prefecture from 1995 to 2002 (272,813 people; 5.3% required close examination based on OC-Sensor results, of whom 69.8% received one) to ascertain the invasive colorectal cancers identified within 2 years after screening. There were 409 cases of colorectal cancer; 76 cases (19%) were interval cancers. Cancer on the right side of the colon accounted for 51% (39/76), which was significantly higher than non-interval cancer, at 31% (103/333) (P<0.001).
Colorectal cancer screening using fecal occult blood tests is reliable, but the percentage undergoing close examination in 2013 was only 66.0%. The examination rate for 40- to 69-year olds based on the Comprehensive Survey of Living Conditions was only 37.9%. To reduce the number of deaths from colorectal cancer in Japan, it is necessary to increase the examination rate for the current colorectal cancer screening using fecal occult blood tests, and establish a low-pain close examination method that would increase the close examination rate. A screening method highly sensitive to cancer on the right side of the colon is required.
