Trial Outcomes & Findings for Screening for Colorectal Cancer in Older Patients (PLCO Screening Trial) (NCT NCT01696981)
NCT ID: NCT01696981
Last Updated: 2025-07-23
Results Overview
Colorectal cancer deaths confirmed in participants by a death review committee if available, otherwise by death certificate.
Recruitment status
ACTIVE_NOT_RECRUITING
Study phase
NA
Target enrollment
154900 participants
Primary outcome timeframe
Events through 13 years of follow-up or through December 31, 2009; median follow-up 12.1 years.
Results posted on
2025-07-23
Participant Flow
Participants were enrolled between November 1993 and July 2001 at 10 study centers. Recruitment was done for all four outcomes of the study (prostate, lung, colorectal and ovarian).
Participants signed a study informed consent prior to being randomized to a study arm.
Participant milestones
| Measure |
Control
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
Overall Study
STARTED
|
77455
|
77445
|
|
Overall Study
COMPLETED
|
76254
|
67071
|
|
Overall Study
NOT COMPLETED
|
1201
|
10374
|
Reasons for withdrawal
| Measure |
Control
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
Overall Study
Cancer Before Rand. (Colo. Screening)
|
0
|
20
|
|
Overall Study
Died Before Randomization
|
3
|
8
|
|
Overall Study
Died Before ASU (Control)
|
278
|
0
|
|
Overall Study
Refused ASU (Control)
|
920
|
0
|
|
Overall Study
Refused Screen (Colorectal Screening)
|
0
|
10346
|
Baseline Characteristics
Screening for Colorectal Cancer in Older Patients (PLCO Screening Trial)
Baseline characteristics by cohort
| Measure |
Control
n=77455 Participants
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
n=77445 Participants
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
Total
n=154900 Participants
Total of all reporting groups
|
|---|---|---|---|
|
Age, Categorical
<=18 years
|
0 Participants
n=5 Participants
|
0 Participants
n=7 Participants
|
0 Participants
n=5 Participants
|
|
Age, Categorical
Between 18 and 65 years
|
49610 Participants
n=5 Participants
|
49634 Participants
n=7 Participants
|
99244 Participants
n=5 Participants
|
|
Age, Categorical
>=65 years
|
27845 Participants
n=5 Participants
|
27811 Participants
n=7 Participants
|
55656 Participants
n=5 Participants
|
|
Age, Continuous
|
62.6 years
STANDARD_DEVIATION 5.4 • n=5 Participants
|
62.6 years
STANDARD_DEVIATION 5.4 • n=7 Participants
|
62.6 years
STANDARD_DEVIATION 5.4 • n=5 Participants
|
|
Sex: Female, Male
Female
|
39111 Participants
n=5 Participants
|
39105 Participants
n=7 Participants
|
78216 Participants
n=5 Participants
|
|
Sex: Female, Male
Male
|
38344 Participants
n=5 Participants
|
38340 Participants
n=7 Participants
|
76684 Participants
n=5 Participants
|
|
Region of Enrollment
United States
|
77455 participants
n=5 Participants
|
77445 participants
n=7 Participants
|
154900 participants
n=5 Participants
|
PRIMARY outcome
Timeframe: Events through 13 years of follow-up or through December 31, 2009; median follow-up 12.1 years.Colorectal cancer deaths confirmed in participants by a death review committee if available, otherwise by death certificate.
Outcome measures
| Measure |
Control
n=77455 Participants
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
n=77445 Participants
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
Colorectal Cancer Deaths
|
341 Participants
|
252 Participants
|
PRIMARY outcome
Timeframe: Events through 13 years of follow-up or through December 31, 2009; median follow-up 12.1 years.Colorectal cancer deaths confirmed in participants by a death review committee if available, otherwise by death certificate. Rate is the number of deaths divided by person years of follow-up in the study.
Outcome measures
| Measure |
Control
n=77455 Participants
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
n=77445 Participants
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
Colorectal Cancer Death Rates
|
3.9 Deaths per 10,000 PY
|
2.9 Deaths per 10,000 PY
|
SECONDARY outcome
Timeframe: Events through 13 years of follow-up or through December 31, 2009; median follow-up 12.1 years.Population: All participants. An intention-to-treat analysis was performed.
Deaths from all causes were compared between the colorectal cancer screening arm and the usual care arm.
Outcome measures
| Measure |
Control
n=77455 Participants
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
n=77445 Participants
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
Deaths From All Causes
|
11064 Participants
|
10835 Participants
|
SECONDARY outcome
Timeframe: Events through 13 years of follow-up or through December 31, 2009; median follow-up 12.1 years.Population: All participants. An intention-to-treat analysis was performed.
Deaths from all causes were compared between the colorectal cancer screening arm and the usual care arm. Rate is the number of deaths divided by person years of follow-up in the study.
Outcome measures
| Measure |
Control
n=77455 Participants
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
n=77445 Participants
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
Death Rates From All Causes
|
127.0 Deaths per 10,000 PY
|
124.3 Deaths per 10,000 PY
|
SECONDARY outcome
Timeframe: Events through 13 years of follow-up or through December 31, 2009; median follow-up 12.1 years.Population: All participants. An intention-to-treat analysis was performed.
Colorectal cancer diagnoses confirmed by medical record abstraction.
Outcome measures
| Measure |
Control
n=77455 Participants
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
n=77445 Participants
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
Colorectal Cancer Incidence
|
1287 Participants
|
1012 Participants
|
SECONDARY outcome
Timeframe: Events through 13 years of follow-up or through December 31, 2009; median follow-up 12.1 years.Population: All participants. An intention-to-treat analysis was performed.
Colorectal cancer diagnoses confirmed by medical record abstraction. Incidence rate (cumulative) defined as colorectal cancer diagnoses divided by person years at risk for colorectal cancer.
Outcome measures
| Measure |
Control
n=77455 Participants
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
n=77445 Participants
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
Colorectal Cancer Incidence Rates
|
15.2 Diagnoses per 10,000 PY
|
11.9 Diagnoses per 10,000 PY
|
SECONDARY outcome
Timeframe: One year from screening examinationPopulation: The units analyzed were positive screening exams with documented diagnostic follow-up. If a participant received 2 positive screens with documented follow-up after each one, he would be counted 2 times in the number of units analyzed.
Number of participants who experienced complications during diagnostic work-up of a positive colorectal examination.
Outcome measures
| Measure |
Control
n=24976 Positive Screens with Follow-up
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
Complications of Diagnostic Evaluation Following a Positive Screening Test
When DE Led to Colorectal Cancer Diagnosis
|
58 Positive screens w/ complications
|
—
|
|
Complications of Diagnostic Evaluation Following a Positive Screening Test
When DE Did Not Lead to Colorectal Cancer Diag
|
279 Positive screens w/ complications
|
—
|
SECONDARY outcome
Timeframe: T0 (at study entry)Population: All participants in the Colorectal Screening arm who had an FSG at T0 were analyzed.
Flexible sigmoidoscopy (FSG) result
Outcome measures
| Measure |
Control
n=64653 Participants
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
T0 (Baseline) FSG Screening Results
Negative
|
42403 Participants
|
—
|
|
T0 (Baseline) FSG Screening Results
Positive
|
15154 Participants
|
—
|
|
T0 (Baseline) FSG Screening Results
Inadequate screen
|
7096 Participants
|
—
|
SECONDARY outcome
Timeframe: T3 (three years after entry) or T5 (five years after entry)Population: All participants in the Colorectal Screening arm who had an FSG at T0 or T3 were analyzed.
Flexible sigmoidoscopy (FSG) result
Outcome measures
| Measure |
Control
n=41858 Participants
Participants receive standard medical care. Participants complete a baseline questionnaire at entry and a dietary history questionnaire (DHQ) during study years 0-6.
|
Colorectal Screening
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|---|
|
T3/T5 FSG Screening Result
Negative
|
26694 Participants
|
—
|
|
T3/T5 FSG Screening Result
Positive
|
9818 Participants
|
—
|
|
T3/T5 FSG Screening Result
Inadequate screen
|
5346 Participants
|
—
|
Adverse Events
Colorectal Screening
Serious events: 0 serious events
Other events: 504 other events
Deaths: 0 deaths
Serious adverse events
Adverse event data not reported
Other adverse events
| Measure |
Colorectal Screening
n=77445 participants at risk
Participants undergo a colorectal examination with a flexible sigmoidoscope at baseline and year 5. Participants complete a Dietary Questionnaire (DQX) at baseline and a Dietary History Questionnaire (DHQ) at study years 3-6. An Annual Study Update (ASU) (previously referred to as the Periodic Survey of Health \[PSH\] questionnaire) is mailed to each participant annually for 13 years to identify all prevalent and incident colorectal cancers and all deaths that occur among both screened and control arm subjects during the trial.
|
|---|---|
|
General disorders
Anxiety
|
0.00%
2/77445 • Number of events 2 • During each annual screening visit.
These events are solely those prompted by the screening examination.
|
|
General disorders
Bleeding
|
0.07%
53/77445 • Number of events 53 • During each annual screening visit.
These events are solely those prompted by the screening examination.
|
|
General disorders
Dizzy
|
0.26%
204/77445 • Number of events 210 • During each annual screening visit.
These events are solely those prompted by the screening examination.
|
|
General disorders
Fainted
|
0.13%
101/77445 • Number of events 101 • During each annual screening visit.
These events are solely those prompted by the screening examination.
|
|
General disorders
Nausea
|
0.13%
101/77445 • Number of events 101 • During each annual screening visit.
These events are solely those prompted by the screening examination.
|
|
General disorders
Pain
|
0.05%
41/77445 • Number of events 42 • During each annual screening visit.
These events are solely those prompted by the screening examination.
|
|
General disorders
Perforated Bowel
|
0.00%
3/77445 • Number of events 3 • During each annual screening visit.
These events are solely those prompted by the screening examination.
|
|
General disorders
Other Adverse Event
|
0.01%
7/77445 • Number of events 7 • During each annual screening visit.
These events are solely those prompted by the screening examination.
|
Additional Information
Paul F. Pinsky, Ph.D.
Early Detection Research Group, NCI, NIH
Phone: 301-496-8544
Email: [email protected]
Results disclosure agreements
- Principal investigator is a sponsor employee
- Publication restrictions are in place
Restriction type: LTE60