Incidence and risk factors of colorectal cancer based on 56 324
health checkups: A 7-year retrospective cohort study
Masayuki Ohisa,* Toru Sako,
Kazuaki Sakamune,* Shintaro Nagashima,*
Aya Sugiyama,* Yuichiro Matsuura
and Junko Tanaka*
*Department of Epidemiology, Infectious Disease Control and Prevention, Graduate School of Biomedical and Health Sciences, Hiroshima University,and
General Affairs, Foundation for Community Health and Medicine Promotion in Hiroshima Prefecture, Hiroshima, Japan
incidence of colorectal cancer, incidence of
FOBT-positivity, person-year method,
retrospective cohort study, risk factors for
Accepted for publication 11 October 2017.
Professor Junko Tanaka, Department of
Epidemiology, Infectious Disease Control and
Prevention, Graduate School of Biomedical and
Health Sciences, Hiroshima University, 1-2-3
Kasumi, Minami-ku, Hiroshima 734-8551, Japan.
Financial support: No funding to declare.
Background and Aim: Although mortality rates of colorectal cancer (CRC) have been
increasing in Japan, its screening rates remain stagnant at 19.2% among Japanese
population aged > 40 years in 2014. To evaluate the importance of CRC screening by fecal
occult blood test (FOBT), this study estimated the incidence of FOBT-positivity and CRC
by sex–age stratiﬁcation and clariﬁed the risk factors for CRC.
Methods: Between 2007 and 2014, 56 324 residents (21 517 men and 34 807 women)
were enrolled in this study. The sex–age-stratiﬁed incidence rates of FOBT-positivity
and CRC were estimated by records from health checkups and colonoscopy. Regarding
CRC incidence rate in particular, positive predictive value was adopted to adjust bias of
FOBT-positivity that did not undergo colonoscopy by person-year method. To investigate
the risks of CRC onset, a nested case–control study with 1:10 person-matching on sex and
age was performed.
Results: Incidence rates of FOBT-positivity and CRC are 4183/100 000 person-year
(100 Kpy) and 141.3/100 Kpy, respectively. In both cases, men has higher incidence rate
than women (1.3 times for FOBT; 4977 vs 3718/100 Kpy and 2.3 times for CRC; 217.0
vs 96.4/100 Kpy).
Conclusions: The records from health checkups were useful to estimate incidence rates of
CRC with this procedure. The age-stratiﬁed incidence rate indicated the importance of
CRC screening by FOBT, especially for men and those aged > 50 years. Additionally, it
is strongly recommended to do further investigation if positive for initial FOBT screening
especially for those who are > 70 years.
Since 1981, malignant neoplasms have been the leading cause of
death in Japan,
and their number of deaths in 2015 was 370 346
(304.6 per 100 000 population, 28.7% of all deaths). Among them,
lung cancer becomes the most common cause of death in men
while colorectal cancer (CRC) is the most common in women
since 2003. Meanwhile, CRC is the third leading cause in men.
In June of 2007 in Japan, Basic Plans to Promote Cancer
were formulated based on the Cancer Control Act
(Act No. 98 of 2006, MHLW), and these plans set the framework
for measures to be administered, such as cancer screening for all
people over 40s and cancer registration system. Cancer screening
aims to decrease the number of cancer deaths by performing
early detection and treatment.
However, the rates of cancer
screening were very low: only 16.1% for lung cancer (14.1%
for men, 17.4% for women), 9.3% for stomach cancer (8.6%
for men, 9.8% for women), and 19.2% for CRC (16.3% for
men, 21.3% for women) of the population aged above 40 years
Furthermore, the examination rate by colonoscopy after
receiving positive results of fecal occult blood testing (FOBT)
screening in 2012 was 64.4% in Japan and 63.4% in Hiroshima
Prefecture, but it should be 100% to reduce the CRC mortality.
The aim of this study was to consider the importance of FOBT
screening for CRC based on the records from 14 cities and towns
in the Hiroshima Prefecture. Therefore, we estimated the inci-
dences of FOBT-positivity and CRC among the general popula-
tion during a 7-year period and clariﬁed the risk factors for CRC
using a 1:10 matched nested case–control study approach.
Subjects. A total of 267 938 residents from 14 cities and towns
in the Hiroshima Prefecture (total 23 cities and towns) underwent
regional health checkups at the Organization in Hiroshima prefec-
ture (“the Organization”) between April 2007 and March 2014.
Among them, a total of 153 351 residents were tested for CRC
screening by FOBT.
Based on identiﬁcation numbers associated with residents and
attached to their results of FOBT screening and colonoscopy, we
retrospectively followed each subject in the database.
Journal of Gastroenterology and Hepatology 33 (2018) 855–862
© 2017 Journal of Gastroenterology and Hepatology Foundation and John Wiley & Sons Australia, Ltd