Background: The survival rate reflecting prognosis of breast cancer patients is usually estimated based on crudesurvival methods such as observed and cause-specific. In situations where data are based on population-cancerregistries, this method may produce biased estimations. This study therefore aimed to estimate the net survival ofbreast cancer based on relative survival. Materials and Methods: Data for 622 breast cancer patients diagnosedat the Iran Cancer Institute during 1990-95 and tracked till the end of 2000 were analyzed. For estimation ofrelative survival, Ederer’s second method and SAS (9.1) and STATA (11) software were used. Results: Threeyearrelative survivals of 85%, 90%, 80% and 67% were observed for age groups 15-44, 55-59, 60-74, and 75+years-old, respectively. A relative survival of approximately one was observed for two subsequent years forage-group 45-59 years-old. A value greater than one for two subsequent years of follow-up was observed in theage-group 60-74 years-old. Conclusions: Tracking the diagnosis of breast cancer, the relative survival decreasesas we go to higher age-groups. It is also perceived that through follow-up, relative survival first decreased andthen increased a little. The statistical cure point is acceptable for age group 45-59 years-old while for age-groups15-44 and 60-74 years old is a sign of low quality data for some follow-up intervals.
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