Abstract A73: Multiple primary malignancies in early-stage breast cancer patients

Introduction: Early diagnosis and effective local and systemic therapy has reduced the risk of relapse and death from breast cancer; thus, patients are living longer but experience an increased risk for the development of multiple primary malignancies (MPM). Risk factors for MPM may be genetic, related to environmental or behavioral factors, or to breast cancer treatments such as radiotherapy, chemotherapy or hormone therapy. Controversy exists over the role of obesity and breast cancer outcomes and there is little information on long-term survivors. LSUHSC-Shreveport provides care for a predominantly indigent with high rates of obesity. This allows us to study the role of obesity in MPM before and after breast cancer diagnosis. In this study, we sought to determine the prevalence and risk factors for MPM in women with early stage breast cancer with emphasis in the role of obesity. Methods: We performed a retrospective analysis of all patients treated for invasive breast cancer from 1980 through 2006 at LSUHSC Shreveport. Patients with stage IV at diagnosis were excluded. Multiple primary malignancies (MPM) were defined as a different diagnosis of primary malignancy in patients with a history of breast cancer. MPM were divided in two categories depending on the interval between malignancy and breast cancer diagnosis. Tumors diagnosed before and within 3 months after breast cancer diagnosis were termed prior/synchronous tumors (PST). Tumors diagnosed ≥ 3 months after breast cancer diagnosis were termed secondary tumors (ST). We reviewed the demographics, smoking status, BMI at diagnosis of breast cancer, tumor characteristics, breast cancer treatments, site and date of MPM and last follow up. Descriptive statistics were performed to characterize the group of patients who developed MPM. Log rank test was used to estimate differences in overall survival between patients with MPM and without it. Results: Of the 1246 patients analyzed, 48% were obese and 29% were overweight. MPM was found in 164 patients (13%): 46 patients had PST and 118 had ST. The median time for development of PST was 6.9 years prior to breast cancer diagnosis with the most common cancers being endometrial cancer (26%), lymphoma (17%) and melanoma (6%). The median time for the development of ST was 7.6 years after breast cancer diagnosis with the most common cancers being breast cancer (54%), endometrial cancer (13%) and colon cancer (5%) The risk for development of ST increased with length of follow up: 2.3% at 5 years and 10% at 10 years. Patients with ST were more likely to be obese (59%, p=0.03) and to have received radiotherapy (60%, p=0.01) than patients without ST. No differences were observed with race, age at diagnosis, tumor characteristics or breast cancer treatments in patients with MPM. The median overall survival was 5.7 years with no difference in overall survival in patients with MPM (p=0.57). Conclusions: Our study has some limitations typical of retrospective studies and the generalization of the results may be limited. MPM does not affect the overall survival of breast cancer patients and both primary cancers should receive appropriate management with curative intent. We found that obesity at diagnosis of breast cancer is associated with a higher risk of ST. Further studies are needed to define the association of obesity and ST in women with early stage breast cancer. Citation Information: Cancer Epidemiol Biomarkers Prev 2010;19(10 Suppl):A73.