Abstract P1-07-21: Use of serum tumor markers and high cost imaging in women with metastatic breast cancer
Authors: Accordino MK , Wright JD , Vasan S , Neugut AI , Hu JC , Hershman DL 
Published: May 2016

Abstract
Background: Despite data on the sensitivity and specificity of serum tumor marker (STM) tests, there is no evidence to suggest that early changes in therapy related to rising tumor markers have an effect on survival. In fact, the limited data suggests no benefit to early change in therapy. The National Comprehensive Cancer Network recommends monitoring cancer burden in women with metastatic breast cancer (MBC) undergoing therapy; however, they do not provide specific recommendations regarding optimal frequency of STMs or of tumor imaging. We performed a population based analysis to evaluate serum tumor marker usage in patients with hormone sensitive MBC.
Methods: The Surveillance, Epidemiology, and End Results-Medicare database was used to identify female patients with hormone receptor positive MBC diagnosed between 2002 and 2011. For each patient, the dates of STMs (CEA and/or CA 15-3/CA 27.29) were recorded; if either or both CEA and CA 15-3/CA 27.29 were ordered on the same day they were counted as one test. We categorized regular STM use as the percentage of patients who had &gt;4 tests in any year, amounting to tests less than 3 months apart; and very frequent STM use as the percentage of patients who had &gt;12 tests in a year, amounting to tests less than 4 weeks apart. Multivariable analysis was performed to further examine patient characteristics associated with frequent STM use. Odds ratios were calculated comparing positron emission tomography (PET) scan use versus computed tomography (CT) use in women with frequent STM testing.
Results: We identified 3,251 eligible patients. Of these, 2,034 (62.6%) had ≥1 STM test in a given year. On average, patients who underwent STM testing were tested 4 times per year (SD 2.9) for an average of 3 years (SD 2.0). Over half of patients with STM testing had regular testing; 1,065 (52.2%) had STM less than every 3 months, 498 (24.5%) less than every 6 weeks, and 146 (7.2%) less than every 4 weeks apart in any given year. Regular STM evaluation was associated with younger age (65-74 vs 75-84) (OR 1.51, 95% CI 1.25-1.83), later year of diagnosis (OR 1.3, 95% CI 1.04-1.69), and high socioeconomic status compared to low socioeconomic status (OR 1.37, 95% CI 1.08-1.73). Similar factors were associated with very frequent STM use (&gt;12 tests/year). Use of PET scan for tumor imaging compared to CT scan use was higher in women with regular STM evaluation (OR=1.97, 95% CI 1.65-2.35) and in women with very frequent STM evaluation (OR=3.77, 95% CI 2.51-5.66).
Conclusion: Regular use of STMs is common in women with hormone receptor positive MBC. Women who had very frequent STMs were almost 4 times more likely to have expensive tumor imaging. Given the rising costs of cancer care, and the increasing survival time in women with metastatic breast cancer, efforts should be made to determine the optimal timing and modality for evaluating response to treatment.
Citation Format: Accordino MK, Wright JD, Vasan S, Neugut AI, Hu JC, Hershman DL. Use of serum tumor markers and high cost imaging in women with metastatic breast cancer. [abstract]. In: Proceedings of the Thirty-Eighth Annual CTRC-AACR San Antonio Breast Cancer Symposium: 2015 Dec 8-12; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2016;76(4 Suppl):Abstract nr P1-07-21.