BREAST CANCER SCREENINGAnoop Agrawal, M.D.

NEW USPSTF BREAST SCREENING GUIDELINES

Published by US Preventative Screening Task Force in November 2009.

Last published in 2002. Other organizations who publish breast

screening guidelines include: American Cancer Society American College of Obstetrics and Gynecology American College of Physicians

Guidelines were met with great controversy resulting in polarization along medical and political lines.

OPPOSITION AND SUPPORT

Various organizations came out in opposition and in support.

Those in opposition included: American Cancer Society and the American College of Radiology.

Those in support included: National Breast Cancer Coalition, Breast Cancer Action, National Women’s Health Network, American College of Preventative Medicine.

HOW THE 2009 USPSTF CAME ABOUT Despite trials of mammography, optimal

screening policy is controversial USPSTF commissioned several studies to look

into evaluating breast cancer screening strategies.

6 independently established models of breast cancer were used to evaluate 20 screening strategies with varying initiation and cessation ages applied annually or biennially. These models come from Georgetown University

Medical Center/Albert Einstien, M.D. Anderson, Dana-Farber, Stanford, Erasmus Medical Ctr (Netherlands), Univ of Wisconsin/Harvard Medical School

USPSTF GRADING SYSTEM Grade A: high certainty that the net benefit is

substantial. Grade B: high certainty that the net benefit is

moderate or there is moderate certainty that the net benefit is moderate to substantial.

Grade C: moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits – Offer this service only if other considerations support the offering

Grade D: moderate or high certainty that the service has no net benefit or that the harms outweigh the benefits – Discourage use of this service

Grade I: Insufficient evidence. If service is offered, patients should understand the uncertainty about the balance of benefits and harms.

NEW USPSTF BREAST SCREENING GUIDELINES Women aged 40 to 49 who are not at

increased risk due to underlying genetic mutation or history of chest radiation should not be screened routinely. (Grade C) In 2002 guidelines, USPSTF recommended

mammography every 1-2 years for all women older than 40.

Women aged 50 to 74 should be screened every two years. (Grade B) Previously, mammography recommended until

age 70. These two recommendations are the most

controversial.

DATA FOR BIENNIAL SCREENING Conclusion of modeling analysis found biennial

intervals more efficient and provided better balance of benefits and harms than annual intervals.

Demonstrated substantial increases in false-positive results and unnecessary biopsies associated with annual intervals. These harms are reduced by 50% with biennial intervals.

These results are consistent with current understanding of breast cancer pathophysiology: Slow-growing tumors much more common than fast-

growing Ratio of slow to fast-growing tumors increases with age Therefore, little survival benefit gained in annual

screening.

DATA FOR BIENNIAL SCREENING

Biennial screening maintained an average of 81% of the benefit of annual screening with almost half the number of false-positive results.

Initiating biennial screening at age 40 years reduced mortality by an additional 3%, consumed more resources and yielded more false-positive results.

JUSTIFICATION FOR BIENNIAL SCREENING

Mammography is an imperfect screening tool.

USPSTF has stated “this recommendation is not a recommendation against ever screening women age 40 to 49; it is a recommendation against routine screening of women starting at this age.”

NEW USPSTF BREAST SCREENING GUIDELINES

Advisability of screening women aged 75 and older is unclear because of insufficient evidence (I statement).

BREAST SELF-EXAMINATION

Teaching women to conduct breast self-examination is not recommended. (Grade D)

The Task Force found adequate evidence that teaching breast self-examination (BSE) is not associated with decreased breast cancer mortality rates.

In trials of BSE, benign biopsy results increased, and there was no decreases in mortality rates.

Effectiveness of BSE was also called into question in the 2002 USPSTF guidelines, however, evidence was not yet sufficient at the time.

BREAST SELF-EXAMINATION

Promoting BSE has been touted more as a method of empowering women.

Women should still be encouraged to pay attention to their breasts and seek medical care if they note any changes

Current evidence is insufficient in evaluating the benefits and harms of clinical breast examinations (CBE) in women. Trials looking at CBE are ongoing.

OTHER SCREENING MODALITIES

Current evidence is insufficient to determine benefits and harms of either digital mammography or MRI vs. film mammography as for screening. (I statement)

CRITICISM OF GUIDELINES

Data is based on computer models and theory, not prospective data. It may be 15-20 years before the effect of the guidelines can be measured.

System will result in ‘rationing.’ Critics argue that mammography for women

in their 40s does work. For women aged 39 to 49 years,

mammography screening was associated with a 15% decrease in breast cancer mortality rates.

COUNTERPOINT TO CRITICISM

Cost benefit analysis of the guidelines from the ACS cost more than $680,000 per quality-adjusted life-year gained.

Compared to $35,000 per QALY for new guidelines.

One statistical analysis calculated that for a woman in her 40s, a decade’s worth of mammograms would increase her lifespan by an average of 5 days.

Though mammography may be effective, the benefit is tiny and expensive.

CONCLUSIONS

Mammography remains the best breast-cancer screening tool available.

Mammography is a highly imperfect test. There has been a long standing controversy

about screening women in their 40s. Current USPSTF have made a modest

adjustment to better balance risks and benefits of screening the asymptomatic patient.

Bottom line, discuss risks and benefits with each patient. Tailor screening to suit the patient’s risk factors and desires.

REFERENCES

Preventive Services Task Force. Effects of Mammography Screening Under Different Screening Schedules. Ann Intern Med. 2009; 151:738-747.

Truog RD. Screening Mammography and the ‘R’ Word. N Engl J Med Dec 24, 2009;361:2501.

www.medscape.com. Accessed Feb 16-20, 2010.