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1. Surveillance following breast cancer – is it cost-effective? Ternent L, Vale L , MacLennan G, Gilbert F, and the Mammographic Surveillance Health Technology Assessment Group. University of Aberdeen, Scotland, United Kingdom BACKGROUND ECONOMIC MODEL Breast cancer affects 1 in 9 women in the UK. At present, the five-year survival rate in the UK is 82%. It is estimated that there are more than 550,000 women who are alive and have been treated for breast cancer in the UK, which represents 2% of the total female population.1 The specific objectives of our research were to (i) identify feasible management strategies for surveillance and follow-up of women after treatment for breast cancer in a UK context. We estimated, using the best available evidence, whether early detection by surveillance of ipsilateral breast tumour recurrence (IBTR) and metachronouscontralateral breast cancer (MCBC) was cost-effective. • A surveillance programme not only needs to be effective but also cost-effective. Using Markov modelling methods, the cost-effectiveness of various surveillance programmes were compared. The model describes the pathway of care of individuals from the point where they received treatment for breast cancer and would receive some form of ongoing surveillance. This includes their longer term costs and consequences, including those that might arise from any subsequent cancers. We used the model to estimate costs and outcomes of a cohort of women for different surveillance strategies. Figure 1 shows an illustrative representation of the model structure. The objective of the analysis was to identify the strategy that leads to the most effective and cost-effective surveillance strategy. Within the model 4 basic surveillance strategies were compared: • 1. No surveillance • 2. Mammography alone • 3. Mammography + clinical exam • A hypothetical technology with a superior diagnostic performance + clinical exam • To provide estimates of relative cost-effectiveness, the model requires estimates for a range of different types of parameters. These estimates were from analyses of existing data sets, a series of systematic reviews, and focused searches for specific pieces of data. The broad types of data required to populate the economic model relate to: • • The uptake of surveillance and follow-up • • The prevalence, incidence and risk of progression of the disease • • The performance of different strategies (e.g. clinical examinations, mammograms, etc) in terms of the accuracy of the diagnostic tests • • Resource use and unit costs • • Health state utilities METHODS The methods used to address the study question were divided into three stages: • A survey of UK breast surgeons and radiologists to identify current practice and potential alternatives • Two systematic reviews to determine the clinical effectiveness and cost- effectiveness of differing surveillance mammography regimens carried out after treatment for primary breast cancer on patient health outcomes and the diagnostic accuracy of surveillance mammography in the detection of IBTR and MCBC. • Statistical and economic modelling using the results of systematic reviews and analysis of individual patient data from the West Midlands Cancer Intelligence Unit Breast Cancer Registry to determine the effectiveness and cost-utility of differing surveillance regimens. Figure 1 Simplified Markov Model RESULTS Untreated cancer Low risk profile* Untreated cancer Med risk profile Untreated cancer High risk profile No cancer Table 1 shows the results of the base case analyses for the average women treated for primary breast cancer with breast conserving surgery, where women received different types of surveillance at different intervals ranging from 12 to 36 months. These data can be used to inform judgements about what would be the single best strategy for the NHS to adopt for all women who had previously been treated with breast conserving surgery. The costs and outcomes for the ‘No surveillance’ option are the same regardless of the surveillance interval. For the other surveillance strategies, both costs and QALYs fall as the surveillance interval increases. However, for each surveillance strategy the reduction in QALYs is more than compensated for by a reduction in cost. This is illustrated by the reduction in the incremental cost per QALY reported for each strategy as the surveillance interval increases. The surveillance strategy most likely to be cost-effective was mammographic surveillance alone provided every 12 to 24 months. This result held for women who had previously received either breast conserving surgery or mastectomy. Results were sensitive to primary tumour characteristics (size, grade, nodal involvement) used to define the likelihoods of developing an IBTR or MCBC. For women at higher risk of developing IBTR or MCBC Intensive follow-up of women may be however worthwhile. Treated cancer Low risk profile Treated cancer Med risk profile Untreated cancer High risk profile Death Table 1 Results of the base case analysis for women treated for their primary cancer with breast conserving surgery CONCLUSIONS Conclusions remain tentative due to paucity of underlying evidence base but suggest Surveillance is likely to improve survival with a strategy of mammography alone every 12 to 24 months appearing cost-effective. Further primary data is required to confirm these findings. REFERENCE 1Breast cancer - survival statistics [webpage on the Internet]. Cancer Research UK; 2009 [http://info.cancerresearchuk.org/cancerstats/types/breast/survival/index.htm. CONTACT DETAILS Laura TernentResearch Fellow Health Services Research Unit and Health Economics Research UnitUniversity of Aberdeen, 3rd Floor Health Sciences Building, ForesterhillAberdeen, AB25 2ZD Tel: +44 (0)1224 551909 Fax: 01224 554580 Email:l.ternent@abdn.ac.uk ACKNOWLEDGEMENTS HSRU/HERU is funded by the Chief Scientist Office of the Scottish Government Health Directorates. The authors accept full responsibility for this presentation λ = willingness to pay for a quality-adjusted life year (QALY) Website: http://www.abdn.ac.uk/hsru