Breast Cancer Screening in Low- and Middle-Income Countries A Framework To Choose Screening Strategies

Transcription

1 Breast Cancer Screening in Low- and Middle-Income Countries A Framework To Choose Screening Strategies Richard Wender, MD Session code:

2 A Five Step Framework to Guide Screening Strategies in LMICs 1. Choose an evidence threshold to select a screening strategy. 2. Match strategy to the capacity to conduct diagnostic evaluations and to treat patients. 3. Assess data about screening options 4. Take all necessary steps to ensure screening quality. 5. Implement screening with careful evaluation and measurement of outcomes. 2

3 1. Choosing an Evidence Threshold Cancer screening is held to a very strict evidence threshold: Evidence of mortality reduction in at least one randomized trial. Evidence that harms are not excessive. Value of non-randomized trials subject to substantial debate. 3

4 1. Choosing an Evidence Threshold Using this very high threshold has distinct limitations and challenges: Conducting randomized trials in multiple settings is not feasible. Evidence of earlier detection, such as smaller tumor size, is an important marker that has the potential to translate to improved survival. Trials have not assessed every type of important outcome, such as harms of later diagnosis (need for more extensive therapy). 4

5 1. Implication in LMICs A somewhat lower evidence threshold, using intermediate outcomes, such as tumor size, is appropriate. In every circumstance, evidence of timely, practical diagnostic evaluation and effective cancer treatment must be provided. 5

6 2. Match Strategy with Capacity to Conduct Diagnostic Evaluations and Provide Treatment Initial screening tests generally do not provide a definitive diagnosis. A second diagnostic test is almost always required. For a screening strategy to work, diagnostic tests must be available at acceptable risk and cost. In breast cancer screening, needle biopsy of a palpable mass or a mammogramdetected abnormality must be locally available. 6

7 2. Match Screening Strategy to Capacity to Provide Treatment The concept of a screening and treatment strategy is more relevant and helpful than focusing on the initial screening test alone. Effective programs include well defined protocols. Measuring the timeliness and rate of completion of diagnostic evaluations and treatment defines a critical screening strategy quality measure. 7

8 3. Assess Data About Screening Options Mammography Clinical Breast Examination (CBE) Breast Self-Examination Breast Awareness 8

9 The Control of Breast Cancer is a Global Challenge Throughout the world, most breast cancers are diagnosed after symptoms develop, and at an advanced stage. The tumor size of self detected breast cancer is highly variable around the globe. 9

10 The Control of Breast Cancer is a Global Challenge In most of the world, breast cancer screening programs are not widely available. In many countries, screening for breast cancer may be cost effective in some populations or regions, but not in others. 10

11 Natural History of Breast Cancer Disease is present, but not detectable Sojourn time Period in which asymptomatic cancer is screen detectable Screen time Lead time CBE Symptomatic disease Growing Tumor Size & % of Advanced Disease Self Detection Time 11

12 Randomized Controlled Trials of Screening Mammography Combined 21% mortality reduction Beginning 50 years ago, the RCTs established the benefit of detecting asymptomatic breast cancer. 12

13 The Evolving Evidence for Mammography Screening Beyond the Randomized Trials Trend Studies, Incidence-Based Mortality Studies, Case Control Studies 13

14 EUROSCREEN Incidence-based Mortality Estimates for Breast Cancer Mortality Reduction in Women ages 50-69, Exposed Versus Not Exposed to Community-Based Screening J Med Screen 2012;19 Suppl1:

15 Mammography Screening in LMICs May be Possible in the Future Although implementing a mammography screening program is impractical in low-income nations today, mammography remains the only screening method that detects pre-symptomatic, non-palpable breast cancers. Pilot projects of screening mammography in middleincome countries should be pursued. 15

16 Clinical Breast Examination High quality CBE can detect tumors of smaller size in some settings. The strong association between tumor size and prognosis suggests the potential to downsize symptomatic breast cancers and reduce deaths. 16

17 The Benefit of Detecting a Small vs. Large Breast Cancer is Well Established Survival of 2,294 patients with invasive breast cancer by tumor size Survival probability Time in years since diagnosis 1-9 mm mm mm mm mm 50+ mm Source: Swedish Two- County Trial of Breast Cancer Screening

18 Proportion of Lymph Node Positive Tumors by Tumor Size, W-E Trial Tumor Size in mm % Lymph Node + Malignancy grades 1,2,3 T1a (1-5mm) 2.8% T1b (6-10 mm) 7.7% T1c (11-20 mm) 28.8% T2 (21+ mm) 60.2% 18

19 Breast Self Examination vs. Breast Awareness Is there a role for breast self exam? OR Promoting AWARENESS of breast symptoms and the importance of seeking medical care. 19

20 Little Evidence Supporting Systematic Instruction in Breast Self Examination The potential of an important contribution from teaching and doing BSE is unknown. Available evidence suggests that most women will not practice regular, competent BSE. The data on self-detection suggests awareness plays an even more important role. 20

21 The Role of Increased Awareness in Downstaging Breast Cancer The 30-year experience in improved detection of breast cancer in the Breast Unit of the Hospital de Clinicas, Federal University of Rio Grande do Sul, Brazil ( ). Menke CH, et al. The Breast Journal 2007;13(5) 21

22 BSE vs. Awareness At this time, the emphasis on awareness over BSE has proceeded without sufficient attention towards understanding: What awareness means for women on a day to day basis. How awareness is achieved. What awareness can accomplish. Research into how to downsize tumors through awareness and alertness is badly needed. 22

23 4. Ensure High Quality Screening The quality of delivering every step of the screening and treatment plan has a major impact on the costeffectiveness and feasibility of the screening program. Mammograms must be able to downsize cancer stage. CBE must be performed carefully and with high sensitivity. 23

24 5. Implement Screening with Measurement of Outcomes and Continuous Reassessment Screening programs are complex, demanding coordination of many aspects of the screening, diagnostic, and treatment continuum. Measurement of evidence of quality indicators, reassessment of the program, and continuous program improvement must be built into the program. 24

25 Breast Cancer Screening Holds Great Potential Breast cancer screening and improvements in therapy have changed the course of breast cancer in high resource nations. We have the opportunity to implement screening models in low and middle income countries that can reduce the mortality burden that will inevitably result from the rising incidence of breast cancer around the world. 25

26 The American Cancer Society stands ready to work with partners around the world within the Breast Health Global Initiative to implement effective, evidence based, high quality breast cancer screening programs for women who are destined to develop breast cancer. 26