Pediatr Blood Cancer The Association Between Socioeconomic Status and Survival Among Children With Hodgkin and Non-Hodgkin Lymphomas in a Universal Health Care System Denise Darmawikarta, MPH, 1,2 Jason D. Pole, PhD, 1,2 * Sumit Gupta, MD, 3 Paul C. Nathan, MSc, MD, 3 and Mark Greenberg, MB, ChB 2,3 INTRODUCTION Disparities in survival among adult cancer patients by socioeco- nomic status (SES) are widespread regardless of how SES is measured (median household income, deprivation scores, individu- al-level data of schooling, income, and occupation) [1]. SES is thought to impact cancer survival via multiple mechanisms, includ- ing delayed diagnosis, differential health-seeking behavior, access to care, and presence of co-morbidities. The association between SES and cancer survival has not been investigated as extensively in the pediatric population. Most literature regarding SES and survival among pediatric oncology patients has been focused on children with acute lymphoblastic leukemia and is contradictory [2], with some studies reporting no difference in survival [3,4], while others report a >50% difference in the risk of death by SES strata [5–7]. Some studies based in the United States (US) over the last 20–25 years have looked at race/ethnicity as a proxy for SES. These studies have demonstrated that where equal access to comprehen- sive treatment is provided, for example, in individual centers that provide care without cost to patients, no disparity in overall sur- vival exists. However, in the overall population of the United States a survival disparity between white and black patients still exists for most childhood cancer diagnoses [8,9]. Lymphoma is the third most commonly diagnosed cancer in Canadian children [10]. Between 2003 and 2007, 1,100 Canadian children and adolescents aged 0–19 years were diagnosed with either Hodgkin lymphoma (HL) or non-Hodgkin lymphoma (NHL) [11]. Despite its prevalence, only two studies have exam- ined the impact of SES on survival among adolescents and young adults with HL [12] and NHL [13]. In the first study in a US population, the authors demonstrated disparities in survival by SES and ethnicity, which they suggested were influenced by inequities in medical treatment and clinical care [12]. In the second study, US adolescents and adults who were of higher neighborhood SES at diagnosis had better lymphoma-specific and overall survival [13]. This relationship persisted after adjust- ment for other demographic and treatment variables, but was attenuated after stratification by race/ethnicity. Canada’s universal health care system ensures that most health care (except for procedures not deemed medically necessary and outpatient medications) is covered by provincial insurance plans for all residents. Consequently, residents make no direct payment for medical services, including in-hospital procedures such as chemotherapy, radiotherapy, surgery, and hematopoietic stem cell transplantation. Despite universal health coverage, SES gra- dients in cancer-specific survival have been demonstrated among Canadian adults [14,15]. Whether similar gradients exist among children with cancer is unknown. Our objective was to determine the relationship between SES and survival among children with HL and NHL in the province of Ontario, and to determine which mechanisms play a role in the relationship between SES and survival, if any. We hypothesized that SES could influence sur- vival at three different phases in the cancer trajectory: (1) prior to diagnosis, (2) over the course of treatment, and (3) in long-term survivorship. METHODS Study Population The cohort was identified from the Pediatric Oncology Group of Ontario Networked Information System (POGONIS) database, an active pediatric cancer registry administered by the Pediatric Oncology Group of Ontario (POGO). POGONIS collects prospec- tive data on all cases of childhood cancer diagnosed at any one of Background. The association between socioeconomic status (SES) and cancer survival has been studied extensively in adults. However, little is known about this relationship in the pediatric population, specifically in jurisdictions with universal health care insurance programs. Our aim was to determine whether lower SES is associated with poorer survival in pediatric Hodgkin (HL) and non-Hodgkin lymphoma (NHL) patients in Ontario. Procedure. All incident cases of HL and NHL in children between 0 and 14 years old diagnosed in Ontario between January 1st, 1985 and December 31st, 2006 were identified through the Pediatric Oncol- ogy Group of Ontario Networked Information System. Neighbor- hood income quintile and material deprivation quintile at diagnosis were used as proxies for SES. Cox proportional hazards regressions were used to assess the association between SES and the risk of event-free or overall survival. Results. A total of 692 patients were included in the analysis: 302 HL and 390 NHL. SES was not asso- ciated with survival (overall or event-free) among HL and NHL patients (P > 0.05 for all four comparisons, i.e., HL/NHL, EFS/OS) after adjustment for age, sex, period of diagnosis, and disease stage. There were no differences in the distribution of disease stage across SES strata at the time of diagnosis. Similarly, the distribution of deaths among long-term survivors (survived 5 years from diagno- sis) did not differ across SES strata (P > 0.05). Conclusions. SES was not associated with risk of death among pediatric HL and NHL patients in Ontario. This was consistent through the cancer trajectory, including diagnosis, treatment, and survivorship. Pediatr Blood Cancer ß 2012 Wiley Periodicals, Inc. Key words: epidemiology; lymphoma; pediatric oncology 1 Dalla Lana School of Public Health, University of Toronto, Ontario, Canada; 2 Pediatric Oncology Group of Ontario, Toronto, Ontario, Canada; 3 Division of Hematology/Oncology, The Hospital for Sick Children, Toronto, Ontario, Canada Conflict of interest: Nothing to declare. *Correspondence to: Jason D. Pole, PhD, Pediatric Oncology Group of Ontario, 1040-480 University Ave, Toronto, ON, Canada M5G 1V2. E-mail: jpole@pogo.ca Received 15 August 2012; Accepted 3 October 2012 ß 2012 Wiley Periodicals, Inc. DOI 10.1002/pbc.24386 Published online in Wiley Online Library (wileyonlinelibrary.com).