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Colorectal Cancer Screening for Older Adults

Colorectal Cancer Screening for Older Adults

Overview of the Study

Colorectal cancer (CRC) is the second most deadly cancer worldwide. As such, the need for resilient colorectal cancer screening (CRCS) is increasingly becoming more important to reduce complications due to delays in care. However, the realistic participation target remains unelucidated. 

This research aims to identify the lowest acceptable participation rate in CRCS with regard to vulnerable older populations who require immediate intervention. Colorectal cancer screening requires resilience as early detection is critical to long term outcomes. This study revealed that, for vulnerable older populations, participation rates ≥38% for the primary screening and ≥ 85% for the follow-up should be achieved to maintain early detection of colorectal cancer.  

Successful implementation of this study can help resilient target setting by serving as a foundation for balancing the resources between cancer screening and pandemic measures, or a minimum target for shifting to a stool test-focused program.

Colorectal cancer screening (CRCS)

The pandemic-related shutdowns disrupted ongoing CRCS. Statistics show that screening rates declined from 28% to 100%. The impacts appeared greater for regions where screening programs were paused for long periods of time, and for pandemic-vulnerable segments of society, such as older populations. Given that colorectal cancer (CRC) is the second most deadly cancer worldwide, it is vital to create a pandemic-resilient CRCS, especially for vulnerable populations.

The researchers clarified the lowest acceptable limit for the screening rate. It was expected that the lowest limit screening rate indicates what percentage of screening rate should be achieved (to what extent screening rate can be compromised) during the pandemic. The lowest limit for screening rate by fecal immunochemical test (FIT) can also suggest what level of screening rate is necessary for shifting to a FIT-focused program effectively.

In addition, the researchers recognized that the older population is the segment requiring urgent intervention. The reasons are the following:

  • Healthcare access is disproportionately affected in this population 
  • CRCS backlogs for those aged ≥70 years increased considerably during the 2020 pandemic
  • Delayed CRC diagnosis is more critical in them
  • The importance of cancer prevention is still sufficiently focused in this group
  • The impacts on CRC incidence are substantial in this age group


This nationwide cross-sectional study included 80,946 inpatients aged 70–85 years who were first diagnosed with colorectal cancer (CRC) after 70 years of age, between April 1, 2014, and March 31, 2019, in Japan. To evaluate the association between area-level CRCS participation rate and individual early CRC detection, a multilevel logistic regression model was constructed. The mandatorily implemented screening rates were converted to the total screening rate equivalents (TSREs), which reflect the remaining contributions of voluntarily provided screenings.

Study population

The researchers used an anonymized dataset extracted from the Diagnosis Procedure Combination/Per-Diem Payment System (DPC/PDPS) database, a medical claim-based national database.

The DPC/PDPS database includes information on individual patients, such as age, sex, International Statistical Classification of Diseases, Tenth Revision (ICD-10) code, stage at diagnosis, medical procedures, insurance type, and postal code. 

As of April 1, 2018, the DPC/PDPS covered 1730 hospitals and 488,563 beds, and Japan’s acute inpatients were regarded as almost fully accommodated. This study included 1165 DPC/PDPS members and 98 nonmember hospitals.

A total of 174,469 inpatients were identified through DPC/PDPS dataset who (1) were aged 70–85 years;12 (2) completed hospitalization between April 1, 2014, and March 31, 2019; (3) were first diagnosed with CRC (ICD10 codes: C18.0–C18.9 and C26.0 for colon, and C19.9 and C20.9 for rectal cancer21); (4) had not been hospitalized for cancers until 70 years of age as an acute admission; and (5) not partaking in a clinical trial. 

Excluded patients were those with (1) unavailable data for body mass index (BMI) and Brinkman index (BI); (2) unmatched municipal codes and missing screening or follow-up rate; and (3) were from municipalities with small population sizes (the number of follow-up candidates by sex and age group was estimated to be <30). Consequently, 80,946 records (468 municipalities or administrative districts22) were extracted for our main analyses.

Primary outcome

The primary outcome of this study was early detection of CRC during stages 0–I. This was mainly because the detection of CRC during stages 0–I, where the survival rate remains over 90% (91.6–94%),  is crucial for mortality reduction. Besides, as the probability of main lymph node metastases remains <1% for these earlier stages, first-line therapies (endoscopic or surgical treatment) are less invasive and hence, less costly. Cancer staging was based on the Japanese Classification of Colorectal, Appendiceal, and Anal Carcinoma developed consistent with the Union Internationale Contre le Cancer staging system.


Early detections during stages 0–I were significantly observed when the primary screening rate was ≥38% (TSRE) and the combined follow-up rate was ≥85%. For early detection during Tis–T1, a primary screening rate of≥ 38% (TSRE) and a combined follow-up rate of≥ 90% were necessary. For follow-up rates ≥70% or ≥75%, there were cases where missed detection of Tis–T1 was observed.


The results indicate that, even during the pandemic, CRCS should achieve a primary screening rate of 38% and a follow-up rate of 85% for vulnerable older populations. These values, lower than the current desirable rates, suggest the maximum possible compromise in balancing the resources between cancer screening efforts and outcome measures. Moreover, they also indicate the minimum target for shifting to a fecal immunochemical test-focused program. Further explorations with varied CRCS settings are necessary for verification.

By defining the older population as a segment requiring urgent intervention in the ongoing pandemic, the researchers reported here that the screening rate ≥ 38% and combined follow-up rate ≥ 85% are necessary to sustain the area-level early detection of CRC (stage 0–I). Below these threshold values, the two-step CRCS may not perform as expected. Therefore, importantly, it is suggested that the screening rate of 38% and combined follow-up rate of 85% be regarded as the lowest acceptable limits to be achieved, even during pandemics.

The lowest acceptable limits present a reasonable fit with the currently set target rates. The primary screening rate of 38% was found to be moderately lower than the desired rate in Japan (50%), and considerably lower than the EU and Canadian desirable levels (65% and 60%, respectively).34, 35 An 85% follow-up rate lies below the common desirable level in Japan and the EU (90%). These relationships imply that the lowest acceptable limits can help pandemic-resilient target setting because the participation targets can be made more flexible with a clear, maximum compromise of 12–27% for the primary screening rate and 5% for the combined follow-up rate to optimize balanced pandemic measures.

Unexpected issues were observed in comparison with the current screening rates. The threshold screening rate of 38% is comparable with Japan’s current screening rate for those aged 70–84 years (37.0%). Also, the 38% rate has not been achieved in some regions, such as France (34.3%, 2008–2009), the Czech Republic (22.7%, 2000–2011), Croatia (19.9%, 2007–2011) in the EU,36 and Prince Edward Island (33%), New Brunswick (30%), and Newfoundland and Labrador (20.4%) in Canada (2017).

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