Table 2.

Methods Used to Estimate Breast Cancer Specific Survival

Method	Description	Comments
Relative survival	Observed all-cause survival in cancer patient cohort divided by survival for a comparable age, race, sex, and year cohort from an appropriate geographical region.	Does not use or require COD information. External reference population must be suitably representative of cancer cohort.
Death certificate based survival	Survival computed using death with cause reported as breast cancer (or unknown) as the event. Other-cause deaths treated as censored.	Depends on accuracy of reported COD. How missing COD are treated will influence estimate (here we treat as breast cancer death)
Recurrence algorithm based survival	Survival computed assigning deaths preceded by breast cancer events (recurrence, new primary) as breast cancer death. Deaths without breast cancer events after initial diagnosis treated as censored.	Requires clinical event history – whether cancer recurred after initial diagnosis. Information about time and type of recurrence will be additionally informative.