Two retrospective cohort studies reported at a pre-conference briefing at the American Society of Clinical Oncology (ASCO) Breast Cancer Conference suggest that young women with early-stage breast cancer do not have to substitute mastectomy for breast-conserving treatment simply because of age. In the first study, Julliette M. Buckley, MD, PhD, of Massachusetts General Hospital in Boston, and colleagues analyzed the medical records of 628 female patients aged ≤40 years with stage III or younger breast cancer admitted to the hospital from 1996 to 2008. The median age of the patients was 37 years, 71% received breast-conserving treatment, and the median follow-up period was 72 months. Analysis showed no statistical difference in local recurrence rates between patients treated with breast-conserving therapy and those treated with mastectomy during the follow-up period. The local and distant recurrence rates were 5.6% and 12% at 5 years and 13% and 19% at 10 years, respectively; the disease-free and overall survival rates were 82.5% and 93% at 5 years and 87% and 68.5% at 10 years, respectively. This suggests that mastectomy is a safe option for young female patients. The investigators concluded that the current focus on genetic risk for breast cancer, advances in screening technology, and improvements in systemic and radiation therapy have all contributed to improved overall survival in younger patients. In the second study, Usama Mahmood, MD, PhD, of the University of Texas M.D. Anderson Cancer Center in Houston, and colleagues analyzed data from the U.S. Epidemiology and Surveillance of End Results (SEER) database on 14,764 patients with early-stage breast cancer diagnosed from 1990 to 2007. Patients were 20 to 29 years old, 45% received breast-conserving treatment, and the median follow-up was 5.7 years. Multivariate analyses corrected for potential confounding factors (including year of diagnosis, age, race, medical history, tumor grade, single or multiple lesions, tumor size, number of positive lymph nodes, number of lymph nodes examined, estrogen receptor, and progesterone receptor status) showed that patients treated with breast-conserving therapy versus mastectomy had a higher overall survival (HR, 0.93; P=0.16) or breast cancer-specific survival ( HR, 0.93; P=0.26) were not significantly different. The results were similar to those of a previous study of 4,644 condition-matched patients. This previous study showed similar 10-year overall survival (83.5% vs. 83.6%, P=0.99) and breast cancer-specific survival (85.5% vs. 85.5%, P=0.88) for patients treated with breast-conserving therapy versus mastectomy. The study suggests that treatment options should be fully discussed with patients and that mastectomy should not be chosen based on the assumption of improved survival. Andrew D. Seidman, MD, PhD, an oncologist at Memorial Sloan Katherine Cancer Center in New York, commented that the findings generally suggest that current breast cancer treatments have improved the previously poor prognosis of young breast cancer patients and reflect changes in breast cancer treatment, such as the use of MRI technology to better select patients suitable for breast-conserving treatment and genetic testing and genetic testing to better identify patients carrying deleterious mutations. The conventional wisdom that younger patients should be treated with mastectomy is now being revisited, given that there are indeed biological differences between younger and older patients. It is reassuring to young women that age alone does not seem to be a reason why mastectomy must be performed; factors other than age such as multicentricity of the lesion, BRCA mutations, family history, and especially the fear of recurrence and second cancers in female patients should also be considered. In addition, data from studies on identifying biological subtypes of breast cancer, such as the 21-gene expression profile (Oncotype DX) recurrence score, which helps assess the risk of local recurrence in Luminal A breast cancer, can also be used. He emphasized that treatment should be individualized for young breast cancer patients. Both the investigator and session moderator reported no conflicts of interest.