Date of initiation of the first course therapy for the tumor being reported, using the SEER definition of first course. See also Date 1st Crs RX CoC [1270]. See Chapter V, Unresolved Issues, for further discussion of the difference between SEER and CoC items. See Chapter X for date format. Use Date Initial RX SEER Flag [1261] if there is no appropriate or known date for this item.
Formerly Date of Initial RX--SEER.