Nathalia Botero BIOL-1615-010-F15 The Effect of Young Age in Hormone Receptor Positive Breast Cancer Breast cancer is a malignant tumor that starts in the cells of the breast. A malignant tumor is a group of cancer cells that can grow into (invade) surrounding tissues or spread (metastasize) to distant areas of the body. Over the last few decades there has been an escalation of new cases of breast cancer even in young women. It is the leading cancer related death in women. Studies have shown that young breast cancer patients have more advanced disease and worse survival compared to older patients. Reports have found that breast cancer in young women is associated with advanced stage of disease and unfavorable tumor characteristics frequently attributed to the higher frequency of more aggressive subtypes of cancer. The objective was to determine disease characteristics and survival in the subset of young women with hormone receptor positive (HR+) and HER2 negative (HER2-) cancer. This was a study done by David Geffen School of Medicine in Los Angeles, California, Revlon/UCLA breast cancer center in Los Angeles and The University of California. Where they performed a retrospective review of women with HR+/HER2breast cancer who were treated at their breast cancer center between 2002 and 2010 . Patients were separated into two groups based on their age. First group women 40 years and younger and second group women 40 years and older. Nathalia Botero BIOL-1615-010-F15 All patients underwent surgical management. Pathological variables included receptor status, Her2/neu status, Ki-67, histological grade, modified Bloom and Richardson score and differentiation and lymphovascular invasion. P values for comparing continuous or ordinal variable across groups were computed using the Kruska-Wallis test. Categorical variables were compared using Fisher’s test. Survival probabilities were estimated using the Kaplan-Meier method. Survival curves were compared using the Log rank test. Statistical analysis were conducted using SAS version. Of 669 HR+/HER2- breast cancer cases, 54 (8.1%) patients were 40 years or younger. Younger patients had more Luminal B subtype, high grade, poor differentiation, and increased lymphovascular invasion. Younger women were treated more often with mastectomy and adjuvant chemotherapy. Although the unadjusted recurrence - free survival at median 55 month follow up was lower in younger women, adjusting for stage, there was no significant difference (90.7% Versus 89.3%, p=0.74) between groups. Young patients with HR+/HER2- type had more advanced disease with less favorable histopathologic features. Women 40 years and younger were more likely to have high grade, poorly differentiated tumors and lymphovascular invasion. More younger women also had higher stage of disease which made them more likely to undergo more aggressive breast cancer surgery. This study came with the conclusion that younger patients with HR+/HER2breast cancer have a more developed disease and their treatment is more aggressive than older patients. There were many adverse characteristics of the tumors associated Nathalia Botero BIOL-1615-010-F15 with the younger patients including a higher grade of Luminal B subtype which indicate that young women may have a different tumor biology. But after adjusting for these factors, stage of disease and treatment there was not difference in recurrence free survival between younger and older. Limitations for this study was the small amount of samples available and also the short amount of time of 55 months. The study does not represent the general population as a whole. There might be a variation in patient overtime, specially in multicenter studies. This report is minimal since everything happened at the same oncology team where all the patients were treated in recent years. A larger sample size with more data may bring other clinical results with the differences between young women and older women with HR+/HER2- breast cancer. However, after adjusting for these factors, stage of disease, and treatment, there was no difference in recurrence free survival between younger and older patients.