An Evidence-Based Approach to Colorectal Cancer (CRC) Screening in Average-Risk,

Asymptomatic Adults

Zachary Jarou, MD Candidate, Class of 2014Family Medicine Clerkship, Spring 2013Michigan State University College of Human Medicine

Many Available Screening Modalities

Flexible Sigmoidoscopy (FSIG)

ColonoscopyDouble Contrast

Barium Enema (DCBE)

CT Colonography (CTC) (HS)-gFOBT/FIT Stool DNA (sDNA)

Essentials of Effective Screening

PrevalenceReduction in Morbidity/MortalitySensitivity, Specificity, ReliabilityReasonable CostLow Risk from Screening Test

Prevalence: CRC is 3rd in Cancer Incidence & Mortality in Both Sexes

~140knew caseseach year

~50kyearlydeaths

Lifetime risk of CRC diagnosis in US is 5% (1 in 20)

Reduction in Morbidity/Mortality:

Polypectomies Prevent Carcinomas

10%⅓

96%

adenomas progressto colorectal cancer

of colorectal cancers developfrom adenomatous polypsover a period of 10-15 years

of adults develop ≥ 1 polyps byage 50, this increases with age Early detection & removal of

polyps eliminates the possibility they become cancerous.

Routine screening could save ~19,000 lives per year

Sensitivity, Specificity, Reliability

• Sensitivity (Sn)– Hemoccult II < FIT ≤ Hemoccult SENSA

< FSIG < colonoscopy• Specificity (Sp)– Hemoccult SENSA < FIT ≈ Hemoccult II

< FSIG = colonoscopy • Reliability– FSIG, CTC, colonoscopy = operator-dependent (better

training/more experience improve Sn)– quality standards/minimum volume requirements

USPSTF (2008)

Sensitivity, Specificity, Reliability

• Colonoscopy has superior single-test accuracy compared to other screening modalities– FS+FOBT failed to identify 24% of advanced colonic neoplasia in one

study– CTC or DCBE missed 2.1% 10+ mm polyps and miss rate as high as

26% for smaller polyps• Single FOBT by DRE will miss 95% of CRC

– Patients should take home 3 testing cards with 2 windows each, use one card per day

– Cochrane review = 16% reduction in mortality (RR = 0.84, 95% CI = 0.78-0.90)

– NNS = 1,176; 10k persons completing FOBT annually will prevent 8.5 deaths over 10 years

AFP (2008)

Reasonable Cost: CRC Screening Compares Favorably to Other

Preventive Interventions

Regardless of screening method, the cost per life-year saved ($10-25k) compares favorably with other

commonly endorsed preventive health care interventions

Pignone et al. (2002), AFP (2008) Median cost of colonoscopy is $1,736

Risks of Screening

• Bowel Perforation– CTC = 0-6 per 10,000 – DCBE = 1 per 25,000 – FSIG = 1 per 25,000-50,000– Colonoscopy = 1 per 2,000-3,000 (65% are sigmoid)

• Serious Complications– death or event requiring hospitalization (perforation, major

bleeding, diverticulitis, severe abdominal pain, and cardiovascular events)

– FSIG = 3.4 per 10,000 procedures– Colonoscopy = 25 per 10,000 procedures

Risks of Screening

• Conscious Sedation– FSIG = most performed without (some discomfort)– Colonoscopy = most performed with (cardiopulmonary

complications are ~½ of all adverse events); patients will also miss a day of work and need a chaperone for transportation

• Bowel Prep– FSIG = less intensive (complete or partial)– Colonoscopy = more intensive (complete required)– DCBE/CTC* = complete required, if same day colonoscopy

not available a second bowel prep will be required

Risks of Screening

• False Reassurance from False-Negative Results (gFOBT/FIT)

• Unnecessary Invasive Tests Due to False-Positive Results (CTC)– 10% of first-time CT colonographies found to have

extracolonic abnormalities which may or may not be clinically significant; potential for both benefit & harm

Risks of Screening

• Radiation Exposure (CTC)– radiation exposure reported to be 10 mSv per CTC– at this level of exposure, 1 additional individual per

1000 would develop cancer in his or her lifetime– cumulative radiation risk should be considered in the

context of the growing use of other diagnostic and screening tests that involve radiation exposure.

– improvements in CT colonography technology and practice are lowering this radiation dose

Many Available Screening Modalities

Flexible Sigmoidoscopy (FSIG)

ColonoscopyDouble Contrast

Barium Enema (DCBE)

CT Colonography (CTC) (HS)-gFOBT/FIT Stool DNA (sDNA)

Many Available Screening Modalities

Flexible Sigmoidoscopy (FSIG)

ColonoscopyDouble Contrast

Barium Enema (DCBE)

CT Colonography (CTC)

Detect both adenomatous polyps and cancers.

Many Available Screening Modalities

(HS)-gFOBT/FIT Stool DNA (sDNA)

Detect primarily cancer.

A Tale of Three Guidelines:All Were Published in 2008

• American Cancer Society/US Multi-society Task Force on Colorectal Cancer/American College of Radiology (ACS/USMSTF/ACR)

• Kaiser Permanente Care Management Institute (KPCMI)

• US Preventive Services Task Force (USPSTF)

Everyone Agrees, Screening for Colorectal Cancer Should Begin at

Age 50

What Isn’t Currently Agreed

Upon:

•At what age should screening end?

• Which screening methods are preferred?

Modality USPSTF KPCMI ACS/USMSTF/ACR

Standard gFOBT ✗

✗least preferred due to low

sensitivity & low compliance

✗

HS-gFOBT/FIT ✔ Q1✔ Q1-2

no evidence of incremental benefit if

normal colonoscopy in last 10 yrs

✔ Q1

FSIG ✔ Q5with HS-gFOBT Q3

✔Q10+/- HS-gFOBT/FIT

✔ Q5Q10 In high-quality

centers, regular insertion beyond 40cm (splenic

flexure) with good bowel prep;

+/- annual HS-gFOBT/FIT

Colonoscopy ✔ Q10 ✔ Q10 ✔Q10

CTC ✗insufficient evidence

✗insufficient evidence to

support over other screening tests

✔Q5comparable to optical

colonoscopy with state-of-the-art techniques; repeat

interval has not been studied

sDNA ✗insufficient evidence

✗insufficient evidence to

support over other screening tests

✔high sensitivity, interval

uncertain (one manufacturer

recommends Q5 but insufficient data to

support)

DCBEwas not considered;substantially lower

sensitivity, not been subjected to screening trials, use is declining

✗insufficient evidence to

support over other screening tests

✔ Q5

Modality USPSTF Recommended?

Standard gFOBT ✗

HS-gFOBT/FIT ✔ Q1

FSIG ✔ Q5with HS-gFOBT Q3

Colonoscopy✔ Q10

CTC ✗insufficient evidence

sDNA ✗insufficient evidence

DCBEwas not considered;substantially lower

sensitivity, not been subjected to screening trials, use is declining

between ages 50-75 years old, all are equally effective in life-years gained (assuming 100% adherence)

against routine screening in adults 76-85 years old

strategies differ in total number of colonoscopies required to gain similar numbers of life-years

USPSTF

Modality KPCMIRecommended?

Standard gFOBT

✗least preferred due to low

sensitivity & low compliance

HS-gFOBT/FIT

✔ Q1-2no evidence of

incremental benefit if normal colonoscopy in last

10 years

FSIG ✔Q10+/- HS-gFOBT/FIT

Colonoscopy ✔ Q10

CTC✗

insufficient evidence to support over other

screening tests

sDNA✗

insufficient evidence to support over other

screening tests

DCBE✗

insufficient evidence to support over other

screening tests

with history of routine screening, discontinue at 75

without history of routine screening, discontinue at 80

this study also includes screening recommendations for those at increased risk of CRC

KPCMI

Modality ACS/USMSTF/ACRRecommended?

Standard gFOBT ✗

HS-gFOBT/FIT ✔ Q1

FSIG

✔ Q5Q10 In high-quality

centers, regular insertion beyond 40cm (splenic

flexure) with good bowel prep;

+/- annual HS-gFOBT/FIT

Colonoscopy✔Q10

CTC✔Q5

comparable to optical colonoscopy with state-of-the-art techniques; repeat

interval has not been studied

sDNA

✔high sensitivity, interval

uncertain (one manufacturer

recommends Q5 but insufficient data to

support)

DCBE ✔ Q5

do not specify age to discontinue screening

if colonoscopy is contraindicated due to life-limiting co-morbidity neither CTC nor any other screening tests are appropriate

ACS/USMSTF/ACR

Modality USPSTF KPCMI ACS/USMSTF/ACR

Standard gFOBT ✗

✗least preferred due to low

sensitivity & low compliance

✗

HS-gFOBT/FIT ✔ Q1✔ Q1-2

no evidence of incremental benefit if

normal colonoscopy in last 10 yrs

✔ Q1

FSIG ✔ Q5with HS-gFOBT Q3

✔Q10+/- HS-gFOBT/FIT

✔ Q5Q10 In high-quality

centers, regular insertion beyond 40cm (splenic

flexure) with good bowel prep;

+/- annual HS-gFOBT/FIT

Colonoscopy ✔ Q10 ✔ Q10 ✔Q10

CTC ✗insufficient evidence

✗insufficient evidence to

support over other screening tests

✔Q5comparable to optical

colonoscopy with state-of-the-art techniques; repeat

interval has not been studied

sDNA ✗insufficient evidence

✗insufficient evidence to

support over other screening tests

✔high sensitivity, interval

uncertain (one manufacturer

recommends Q5 but insufficient data to

support)

DCBEwas not considered;substantially lower

sensitivity, not been subjected to screening trials, use is declining

✗insufficient evidence to

support over other screening tests

✔ Q5

My Recommendation

Follow the USPSTF Guidelines.

Racial Disparities in CRC Mortality

African Americans have 20% higher incidence and 45% higher mortality from CRC than whites

Disparities By Insurance Status

Effect of Affordable Care Act on Colorectal Cancer Screening

All new private health plans are required to cover CRC screening

tests with “A”/“B” USPSTF ratings(effective beginning 2011)

Medicare preventive services will

have no out-of-pocket costs & are exempt from deductibles,

even with polypectomy(effective October 2010)

Patient Education Materials

• Information from Your Family Doctor: Colon Cancer Screening (2008). http://www.aafp.org/afp/2008/1215/p1393.html

• National Cancer Institute. Colorectal Cancer Screening (PDQ). http://www.cancer.gov/cancertopics/pdq/screening/colorectal/Patient

• American Cancer Society/US Multisociety Task Force on Colorectal Cancer/American College of Radiology (ACS/USMSTF/ACR). Screening and surveillance for the early detection of colorectal cancer and adenomatous polyps, 2008: a joint guideline from the American Cancer Society, the US Multi-Society Task Force on Colorectal Cancer, and the American College of Radiology. CA Cancer J Clin 2008 May-Jun;58(3):130-60.

• Kaiser Permanente Care Management Institute (KPCMI). Colorectal cancer screening clinical practice guideline. Oakland (CA): Kaiser Permanente Care Management Institute; 2008 Dec. 190 p.

• US Preventive Services Task Force (USPSTF). Screening for colorectal cancer: U.S. Preventive Services Task Force recommendation statement. Ann Intern Med 2008 Nov 4;149(9):627-37.

Guidelines Reviewed

• American Cancer Society. Colorectal Cancer Facts & Figures 2011-2013.

• Pignone et al (2002). Cost-effectiveness Analyses of Colorectal Cancer Screening: A Systematic Review for the U.S. Preventive Services Task Force. AHRQ Pub. No. 03-519

• Wilkins T and Reynolds PL (2008). Colorectal Cancer: A Summary of the Evidence for Screening and Prevention. American Family Physician. http://www.aafp.org/afp/2008/1215/p1385.html

Other References