Copyright © Lippincott Williams & Wilkins. Unauthorized reproduction of this article is prohibited. Older Patients With Early-stage Breast Cancer Adjuvant Radiation Therapy and Predictive Factors for Cancer-related Death Himanshu Nagar, MD,* Weisi Yan, MD, PhD,* Paul Christos, DrPH, MS,w K.S. Clifford Chao, MD,* Dattatreyudu Nori, MD,* and Akkamma Ravi, MD* Purpose: Studies have shown that older women are undertreated for breast cancer. Few data are available on cancer-related death in elderly women aged 70 years and older with pathologic stage T1a-b N0 breast cancer and the impact of prognostic factors on cancer-related death. Methods: The Surveillance, Epidemiology, and End Results (SEER) database was queried for women aged 70 years or above diagnosed with pT1a or pT1b, N0 breast cancer who underwent breast con- servation surgery from 1999 to 2003. The Kaplan-Meier survival analysis was performed to evaluate breast cause-specific survival (CSS) and overall survival (OS), and the log-rank test was employed to compare CSS/OS between different groups of interest. Multivariable analysis (MVA), using Cox proportional hazards regression analysis, was performed to evaluate the independent effect of age, race, stage, grade, ER status, and radiation treatment on CSS. Adjusted hazard ratios were calculated from the MVA and reflect the increased risk of breast cancer death. Competing-risks survival regression was also performed to adjust the univariate and multivariable CSS hazard ratios for the competing event of death due to causes other than breast cancer. Results: Patients aged 85 and above had a greater risk of breast cancer death compared with patients aged 70 to 74 years (referent category) (adjusted hazard ratio [HRs] = 1.98). Race had no effect on CSS. Patients with stage T1bN0 breast cancer had a greater risk of breast cancer death compared with stage T1aN0 patients (adjusted HR = 1.35; P = 0.09). ER negative patients had a greater risk of breast cancer death compared with ER positive patients (adjusted HR = 1.59; P < 0.017). Patients with higher grade tumors had a greater risk of breast cancer death compared with patients with grade 1 tumors (referent category) (adjusted HRs = 1.69 and 2.96 for grade 2 and 3, respectively). Patients who underwent radiation therapy had a lower risk of breast cancer death compared with patients who did not (adjusted HR = 0.55; P < 0.0001). Conclusions: Older patients with higher grade, pT1b, ER-negative breast cancer had increased risk of breast cancer-related death. Adju- vant radiation therapy may provide a CSS benefit in this elderly patient population. Key Words: radiation, elderly, survival, breast (Am J Clin Oncol 2014;00:000–000) T he elderly population in the United States continues to increase. As suggested by US consensus data, the number of people who were 65 years and older in the United States reached 40.3 million on April 1, 2010, up from 31.2 million in 1990 to 35.0 million in 2000. 1 According to the Surveillance Epidemiology and End Results (SEER) database, from 2005 to 2009 approximately 41% of patients with breast cancer were diagnosed above the age of 65 years, of which 21% were above the age of 75 years. Breast cancer related deaths during this time period was 57.4% for patients above the age of 65 years, of which 37.5% were above the age of 75 years. Furthermore, annually 40,000 women aged 70 years or above in the United States will be diagnosed with tumors no greater than 2 cm in size. 2 Despite an increase in the incidence of breast cancer in elderly population, the optimal management of breast cancer in the elderly population is unclear. 2 Clinical treatment decisions are based individually on tumor characteristics and treatment side effects against patients’ health status, comorbidities, and life expectancy. 3 There is low enrollment of patients aged 65 years and older in randomized clinical trials. 4–6 Concern that treatment guidelines based on studies in younger patients may not be applicable to elderly patients may lead to elderly patients being undertreated. 7,8 Two randomized trials have called into the question the need for adjuvant radiation after breast conservation surgery (BCS) in the elderly pop- ulation. 9,10 On the basis of the results from these studies, the NCCN guidelines has incorporated lumpectomy alone as a treatment option in patients aged 70 years and older diagnosed with T1 tumors that are node negative and estrogen receptor (ER) positive and are able to take the adjuvant hormone therapy for 5 years. There is lack of literature regarding the various decision- making factors that are considered to omit adjuvant radiation in low-risk, older breast cancer patients. The overall treatment recommendations should take into consideration the patient’s life expectancy and comorbidities. The purpose of this study was to determine the role of radiation therapy (RT) on breast cancer cause-specific survival (CSS) for elderly female patients, age 70 years and above with early-stage breast cancer by analyzing the SEER database. To better tailor therapy for individual patient, a secondary goal of this study is to identify prognostic factors including age, race, grade, hormone receptor status (ER), and use of adjuvant RT on breast cancer-related death. METHODS The SEER database was queried for women aged 70 years and above of age diagnosed with pT1a or pT1b, N0 M0 breast cancer that underwent BCS from 1999 to 2003. Patients From the *Department of Radiation Oncology, New York Presbyterian- Hospital/Weill Cornell Medical College; and wDivision of Biostatistics and Epidemiology, Department of Public Health, Weill Cornell Med- ical College, New York, NY. Dr Paul Christos was partially supported by the following grant: Clinical Translational Science Center (CTSC) (2UL1TR000457-06). The authors declare no conflicts of interest. Reprints: Himanshu Nagar, MD, New York Presbyterian-Hospital/Weill Cornell Medical College, Stich Radiation Oncology, 525 East 68th Street, New York 10065, NY. E-mail: hin9004@nyp.org. Copyright r 2014 by Lippincott Williams & Wilkins ISSN: 0277-3732/14/000-000 DOI: 10.1097/COC.0000000000000144 ORIGINAL ARTICLE American Journal of Clinical Oncology  Volume 00, Number 00, ’’ 2014 www.amjclinicaloncology.com | 1