Redaniel et al. BMC Cancer 2010, 10:100 http://www.biomedcentral.com/1471-2407/10/100 could elucidate the role of prognostic factors, such as stage and treatment, are rare [2,4,5,7]. The term “high resolution study” was first used by the EUROCARE group in comparing cancer survival estimates between populations in Europe, and aims to elucidate possible explanations for survival differences [7-9]. It incorpo- rates information that are usually not available in stan- dard format in population-based registries, such as disease stage and treatment. In previous studies, variations in access to diagnostic and treatment facilities were put forward as the reasons for survival differences between countries and popula- tions [2,4,7]. However, it was also found that biological characteristics, such as age at disease onset and tumor differentiation, vary between ethnic groups [5]. Few stu- dies tried to disentangle how much of cancer survival discrepancies between ethnic groups are explained by ethnicity or by health care conditions. Furthermore, there is also a dearth of published popu- lation-based colorectal cancer survival estimates from developing countries, and comparisons of these with data from developed countries are limited [2,10,11]. Such comparisons are important to determine discre- pancies in access to and utilization of cancer care ser- vices between developed and less developed nations. From the Philippines, population-based cancer survival data were reported for the first time in the 1998 Inter- national Agency for Research on Cancer (IARC) mono- graph “Cancer Survival in Developing Countries” [12], and only more recently in a summary report for this study [13]. Compared to most populations from devel- oped countries, a huge majority of Philippine residents do not have heath insurance and bear the cost of health care from out-of-pocket funds [14]. These circumstances are likely to play a significant role in access to cancer care services, and in turn, to health outcomes, and should be studied further. To elucidate the role of various factors, including eth- nicity, stage at diagnosis, and access to treatment in CRC survival, we compared Filipino-Americans with Philippine residents, who have the same ethnicity, and with Caucasians living in the US, who are exposed to similar health care systems. Methods Databases US SEER Using the United States Surveillance, Epidemiology and End Results (SEER) 13 database [15], CRC patients iden- tified to be of Filipino or of Non-Hispanic White ethni- city were selected. Patients aged 15 and older, diagnosed from January 1, 1993 to December 31, 2002, and fol- lowed with respect to vital status until December 31, 2002 were included in the study. In situ cases and those Page 2 of 9 who were identified by death certificates only (DCO) or autopsy only, which consist <1% of cases, were excluded, leaving 2,671 Filipino-American and 133,551 Caucasian patients to be included in the analysis. Philippine Resident Population Information on CRC cases who were residents of the National Capital Region (NCR) were abstracted from the databases of the Philippine Cancer Society-Manila Cancer Registry (PCS-MCR) and the Department of Health-Rizal Cancer Registry (DOH-RCR). The PCS- MCR covers the four major cities of the NCR (Manila, Quezon City, Pasay and Caloocan), while the DOH-RCR covers the 12 municipalities of the former Rizal province that were incorporated into the NCR and the present Rizal Province. The NCR holds the seat of the Philip- pine government and is the largest urban metropolis, and the political, social, educational and economic center. Data collection procedures include exhaustive identifi- cation and collection of information on patients from all hospitals in the NCR and the Rizal Province, which lim- its underreporting to a minimum. Various patient records were reviewed, including medical, pathology, radiotherapy, radiology, ultrasound, nuclear medicine and CT scan reports, and records from hospital tumor registries, if available. Death certificate notifications (DCN) indicating cancer as the cause of death are also routinely acquired by the registries from all the Local Civil Registry Offices in the constituent cities. The Philippine registries are regarded as among the high-quality cancer registries from developing countries and have consistently been included in Cancer Incidence in Five Continents [16-20]. They follow the cancer regis- tration definitions and data collection guidelines set by the International Agency for Research on Cancer (IARC) and the International Association of Cancer Registries (IACR). The same inclusion and exclusion criteria as for the SEER databases were used in the subject selection. For the Philippine data though, due to limited resources, only subsamples of 200 cases diagnosed in each calendar year from 1993 to 2002 were randomly selected from the 7,769 eligible CRC patients in the database. These were followed with respect to vital status until Decem- ber 31, 2002 and included in the analysis. From DCNs mentioning cancer as the cause of death, survival status was assessed. Active follow-up by personal visits to the patients or their families in the last known place of resi- dence was used to confirm status for those not identi- fied as dead. From the 2000 randomly sampled patients, 160 (8%) were excluded from the analysis due to invalid data while an additional 205 (10.2%) were removed due to the absence of any follow-up information. Anonymized