BREAST CANCER SCREENING

1. BREAST CANCER SCREENING Anoop Agrawal, M.D.

2. 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.

3. 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.

4. 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

5. 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.

6. 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.

7. 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.

8. 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.

9. 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.”

10. NEW USPSTF BREAST SCREENING GUIDELINES • Advisability of screening women aged 75 and older is unclear because of insufficient evidence (I statement).

11. 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.

12. 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.

13. 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)

14. 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.

15. 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.

16. 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.

17. 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.