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Draft Research Plan

Aspirin Use for the Prevention of Colorectal Cancer


Note: This is a draft Research Plan. This draft is distributed solely for the purpose of receiving public input. It has not been disseminated otherwise by the USPSTF.

The final Research Plan will be used to guide a systematic review of the evidence by researchers at an Evidence-based Practice Center. The resulting Evidence Report will form the basis of the USPSTF Recommendation Statement on this topic.

This draft Research Plan was available for comment from June 13 until July 10, 2013 at 5:00 p.m., ET.


I. Background

The U.S. Preventive Services Task Force (USPSTF) has commissioned this systematic review in order to update its 2007 recommendation against the use of aspirin and nonsteroidal anti-inflammatory drugs (NSAIDs) for the prevention of colorectal cancer. A separate systematic review to update the USPSTF's 2009 recommendations on the targeted use of aspirin to prevent cardiovascular disease has been commissioned, and the draft Research Plan will be available in the near future. The draft Research Plan for a third systematic review assessing the risks and benefits of the use of aspirin to prevent all types of cancer in addition to colorectal cancer will also be available in the near future. These three systematic reviews will allow simultaneous consideration of all three bodies of evidence by the USPSTF.

The previous evidence review for the USPSTF on colorectal cancer prevention found fair to good evidence of the benefits and harms of aspirin and/or NSAID medication use but lacked detail about the dosage, duration, and timing of use, particularly for subgroups with varying risk levels. Since the last evidence review in 2007, additional data on the safety of nonaspirin NSAIDs has emerged. As a result, both rofecoxib and valdecoxib are no longer on the market in the United States, leaving celecoxib as the only available selective cyclooxygenase-2 inhibitor. The remaining NSAIDs now include black box warnings on their labels because of increased safety concerns. Given these concerns about NSAIDs, the USPSTF has determined that this review update will focus only on aspirin for the prevention of colorectal cancer.

II. Proposed Analytic Framework

Select Text Description below for details.

Abbreviations: CRC=colorectal cancer; FAP=familial adenomatous polyposis; KQ=key question.

[D] Select for Text Description.

II. Proposed Key Questions to Be Systematically Reviewed

  1. Does regular aspirin use reduce colorectal cancer mortality or all-cause mortality in adults without a history of adenoma, colorectal cancer, familial adenomatous polyposis (FAP), or Lynch syndrome?
    1. Does the effect of aspirin vary by age, sex, comorbidities*, or baseline cancer risk?
    2. Does the effect of aspirin vary by dosage, duration, or recency of use?
  2. Does regular aspirin use reduce the incidence of colorectal cancer in adults without a history of adenoma, colorectal cancer, FAP, or Lynch syndrome?
    1. Does the effect of aspirin vary by age, sex, comorbidities*, or baseline cancer risk?
    2. Does the effect of aspirin vary by dosage, duration, or recency of use?
  3. Does regular aspirin use reduce the incidence of colorectal adenoma in adults without a history of adenoma, colorectal cancer, FAP, or Lynch syndrome?
    1. Does the effect of aspirin vary by age, sex, comorbidities*, or baseline cancer risk?
    2. Does the effect of aspirin vary by dosage, duration, or recency of use?
  4. What are the harms of regular aspirin use for the prevention of colorectal cancer (i.e., at the dosage and duration required to achieve a preventive health effect) in adults without a history of adenoma, colorectal cancer, FAP, or Lynch syndrome?
    1. Do harms vary by patient characteristics (e.g., age, sex, comorbidities*)?

*We propose the following comorbidities, which are prevalent and may be affected by aspirin use in terms of benefits or harms:

  • Diabetes
  • Liver disease

III. Proposed Contextual Questions

Contextual questions are not systematically reviewed and are not shown in the Analytic Framework.

  1. Do the harms or benefits of regular aspirin use for the prevention of colorectal cancer vary when combined with other commonly used medications?
    • Aspirin and nonaspirin NSAIDs
    • Aspirin and proton-pump inhibitors (which may decrease bleeding risk)
    • Aspirin and selective serotonin reuptake inhibitors (which may increase bleeding risk)
  2. What is the level of persistence of aspirin use among adults who initiate a regimen for the prevention of colorectal cancer?

IV. Proposed Research Approach

The Proposed Research Approach identifies the study characteristics and criteria that the Evidence-based Practice Center will use to search for publications and to determine whether identified studies should be included or excluded from the Evidence Report. Criteria are overarching as well as specific to each of the key questions (KQs).

Category Included Excluded
Populations Men and women age 18 years or older
  • Nonhuman populations
  • Children (age <18 years)
  • Studies limited to patients with the following conditions or with a high proportion of such patients who cannot be examined separately:
    • FAP
    • Lynch syndrome
    • Personal history of colorectal cancer
    • Personal history of adenoma
    • Inflammatory bowel disease (Crohn's disease and ulcerative colitis)
    • Persons without a colon
    • Persons with a history of another cancer or familial multiple cancer syndrome that includes colorectal cancer
    • Symptomatic persons (i.e., those undergoing diagnostic colonoscopy)
Interventions KQs 1–3:
  • Oral aspirin
  • Includes medication use for any indication (e.g., primary or secondary prevention of cardiovascular disease, arthritis treatment), as long as intended duration is at least 1 year

KQ 4: No minimum intended duration of use

  • Interventions limited to combined products containing levels of aspirin below 75 mg per day or every other day
  • Interventions limited to nonaspirin NSAIDs
  • Interventions using nonoral routes of delivery
  • Studies with no information on dose
  • Interventions limited to irregular or occasional use only
Comparators
  • Placebo
  • No treatment
  • Includes studies in which both intervention and control groups may be taking other medications or supplements
  • Studies limited to comparison of aspirin with other medications
  • Studies examining aspirin in combination with other medications (i.e., intentional cotreatment) for chemoprevention
Outcomes KQs 1–3 (benefits):
  • Colorectal adenoma incidence
  • Colorectal adenoma number
  • Advanced adenoma incidence
  • Advanced neoplasia
  • Colorectal cancer incidence
  • Colorectal cancer mortality
  • All-cause mortality

KQ 4 (harms):

  • Major nonintracranial bleeding
  • Intracranial bleeding
  • Stroke (any, hemorrhagic)
  • Age-related macular degeneration
Colorectal cancer metastasis or progression
Study Design KQs 1–3 (benefits): Randomized controlled trials (RCTs), controlled clinical trials (CCTs), fair- and good-quality systematic reviews of RCTs, and meta-analyses of RCTs

KQ 4 (harms): All of the above, plus high-quality prospective cohort studies

Case series, case reports, narrative reviews, commentaries, or editorials
Timing No minimum followup  
Setting Outpatient Exclusively inpatient
Country All countries  
Language English Non-English

AHRQ Publication No. 13-05193-EF-5
Current as of July 2013


Internet Citation:

U.S. Preventive Services Task Force. Aspirin Use for the Prevention of Colorectal Cancer: Draft Research Plan. AHRQ Publication No. 13-05193-EF-5. http://www.uspreventiveservicestaskforce.org/uspstf13/asprcolo/asprcolodraftresplan.htm



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