Need help tuning this procedure

Oracle Version:8.1.7

The following is an example of the information that is captured via the monitoring software that is being used and the DBA’s diligence in tracking down the root cause of the problem:

    

SQL Statements with                      

100,000+ Disk reads

USERNAME          READS      EXECS RDS_EXEC_RATIO   CMD_TYPE    

---------- ------------ ---------- -------------- ----------    

STATEMENT                                                         

------------------------------ ------------------------------ -----

BATCHER      13,205,568          1     13,205,568         47    

BEGIN exeter.ESI_ADVERTISING_DGGO1; END;                        

NOTE: 13 million reads

In the cursor loop a check is made if a row exists on CMN_CORRESPONDENCE; if not a row is inserted. The query does a full table scan on the 5,499,400 row table in each iteration of the loop. There is currently no indexes on the where-clause columns. The job that runs this procedure ran for 1 hour 25 minutes this last Sunday.