Survival Analysis of 2003-2005 Data from the Population-based Cancer Registry in Macao


Aim: Macao Cancer Registry was established in 2003. It is population-based and has been collecting cancerreports from all possible settings where pathological and management services are available. To get a betteridea over the prognosis and survival of all and major cancer sites, a survival analysis was here performed toestimate the relative survival rates of cancers diagnosed and registered during 2003 to 2005 with a follow-up ofvital status till 31 Dec, 2008.
Methods: 3,244 cancer cases diagnosed and registered during 2003-2005 in MacaoCancer Registry were considered for analysis. Cases of in-situ carcinoma, extreme age and poor data quality weredeliberately excluded, leaving 2,623 newly diagnosed cancers eligible. Vital status of registered cases through 31December 2008 was confirmed by matching with death certificates and review from the Hospital InformationSystem (HIS) of the only public hospital. Observed survival rates were calculated using a Life Table method,and relative survival rates were examined using an algorithm written in SAS by Paul Dickman with minoradaptations. Apart from general relative survival rates, specific rates by sex and age strata were also estimated.
Results: 3-year and 5-year relative survival rates of all cancers were 61% and 56% respectively for both sexes;(54% and 47%, respectively, for males and 68% and 64%for females). The 3-year relative survival rates formajor cancer sites ranged from 21% to 90%, with lung cancer showing the lowest and female breast cancer thehighest. 5-year relative survival rates for major cancer sites ranged from 18% to 85%, with liver cancer showingthe lowest and again female breast cancer the highest. Female cancer patients had higher relative survival thanmales across the 5-year follow up period, with a sex difference of nearly 15%.
Conclusion: Comparison of survivalrates from this first trial in Macao, deriving survival statistics from population-based cancer registration, withother Asian countries/cities, like Taiwan, Singapore and Japan, showed Macao and Taiwan to have the closestestimates for 3-year relative survival. Random variation was found to exist in the stratification of sex and age incertain cancer sites due to scarce case numbers in the subgroups. It is important to note that the 3-year survivalrates are relatively more consistent and reliable than 4-year or 5-year ones. Promotion of reporting cancerstage by physicians as well as improvement in data quality of cancer registration are essential to allow furtherinformative statistics derived from the cancer registry with reference to cancer prevention.