How long after surgery for a keloid can you wait to treat with post-operative radiation before the treatment becomes ineffective?

The literature has indeed shown "the sooner, the better."

Initial studies looking at this question reported that the most effective time to give adjuvant radiation was within the first 1-2 weeks after excision. However, this treatment window was soon shortened to treatment delivery to be within 72 hours (3 days) (PMID: 25673932).

More recently, an increasing number of studies have recommended for an even shorter time interval between surgery and the start of RT treatment, with post-operative RT ideally to be delivered within 24-48 hours (PMIDs: 19362243, 15250893, 16254707, 7085377).

The ideal time interval to start of post-operative RT has been even further shortened to <7 hours based on a recent systemic review (PMID: 26301129), in which tr...

In PP, I try to treat the same day as surgery, if possible