I don’t think there is any set way to do this - I don’t recall seeing it in any of the various Cancer TAs.
For myself, as a Cycle will normally start with a visit I would encapsulate the Cycle into VISIT and VISITNUM
If there is only a single visit per cycle - I would probably use something like
VISIT = Cycle x
VISITNUM = x
However, if the protocol calls for multiple visits per cycle, e.g. days 1, 15, 28 in each Cycle I would probably use something like
VISIT VISITNUM
Cycle x, Day 1 x01
Cycle x, Day 15 x15
Cycle x, Day 28 x28
That way Cycle number is embedded into VISITNUM in a consistent way, and can be later extracted into an ADaM variable if required.