Sub Demo()
Dim tRng As Range
With Selection
  With .Find
    .ClearFormatting
    .Replacement.ClearFormatting
    .Text = "TOC"
    .Replacement.Text = ""
    .Forward = True
    .Wrap = wdFindContinue
    .Format = False
    .MatchCase = False
    .MatchWholeWord = False
    .MatchWildcards = False
    .MatchSoundsLike = False
    .MatchAllWordForms = False
  End With
  While .Find.Execute
    With .Range
      If .Information(wdWithInTable) = True Then
        Set tRng = .Tables(1).Cell(.Cells(1).RowIndex + 1, .Cells(1).ColumnIndex).Range
        tRng.End = tRng.End - 1
        ActiveDocument.Indexes.MarkEntry Range:=tRng, EntryAutoText:=.Text, _
          CrossReference:="", CrossReferenceAutoText:="", BookmarkName:="", Bold:=False, Italic:=False
      End If
    End With
  Wend
End With
End Sub