Abstract P3-06-02: The use of imaging and tumor markers in the staging of patients age <65 years with early-stage breast cancer

Abstract

Abstract Purpose Guidelines from the American Society of Clinical Oncology (ASCO) and the National Comprehensive Cancer Network (NCCN) recommend against the use of positron emission tomography (PET), computed tomography (CT), radionuclide bone scans (RBS) and tumor markers (TM) in the staging of early-stage breast cancer with a low risk for distant metastasis. No previous studies have described the use of these tests or identified factors associated with this practice in patients age <65 years. Methods We used the national employer-based claims database MarketScan to identify patients with a first diagnosis of breast cancer, age 20 to 64 years, who had undergone a mastectomy or a lumpectomy, and a sentinel lymph node biopsy between the years of 2005 and 2010. We excluded patients who had undergone an axillary lymph node dissection, as this may indicate advanced nodal disease for which staging tests may be recommended. We ascertained claims for PET, CT, RBS and TM during the period of 3 months before and 1 month after the date of surgery. We used a multivariable logistic regression model to identify factors associated with the use of these tests. The variables included in the model were: age at diagnosis, geographic region, year of diagnosis, type of surgery (lumpectomy vs. mastectomy), endocrine therapy (yes vs. no), radiation therapy (yes vs. no), and chemotherapy (trastuzumab-based, non-trastuzumab-based, vs. no). Results We identified 42,606 patients (median age 53 years) of whom 12% had at least one claim for a PET, 6.5% for a CT, and 2.5% for TM. In combination, 17% of the patients had at least one claim for a test. Among patients diagnosed in 2005, 14% had claims for tests, whereas between 2006 and 2010, this proportion ranged between 16% and 18% (test for trend p-value: 0.08). Among patients who had chemotherapy, 22% of those who received trastuzumab-based regimens and 21% of those who received non-trastuzumab-based regimens had claims for tests, compared to 14% of patients who did not receive chemotherapy. In the regression analysis, we observed geographic differences, where patients from the Northeast had increased odds of testing, compared to patients from the North Central region (odds ratio [OR] 1.46, 95% confidence interval [CI] 1.34 - 1.59). Patients who underwent a lumpectomy had decreased odds of testing, compared to those who had a mastectomy (OR 0.62, 95% CI 0.57 - 0.66). Patients who received radiation therapy (OR 1.30; 95% CI 1.20 - 1.40) and chemotherapy (non-trastuzumab-based: OR 1.67, 95% CI 1.58 - 1.77; trastuzumab-based: OR 1.69, 95% CI 1.55 - 1.84) had increased odds of testing. Conclusion Despite current ASCO and NCCN guidelines, the use of imaging tests and TM in the staging of early-stage breast cancer remains common, and there is no clear trend of a change of this non-recommended practice over time. Subsets of patients with early-stage breast cancer had an increased probability of undergoing tests not recommended for staging purposes. The use of imaging tests and TM may be increased in those patients who are perceived to be at a higher risk for metastasis during diagnosis, as there was a significant association of this practice with mastectomy (over lumpectomy), radiation therapy and chemotherapy. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr P3-06-02.