Caution is required for previously radiated areas. If an area of skin has already received a full course of radiation in the past, we generally try to avoid re-irradiating the exact same area with a full dose because of the increased risk of tissue damage. However, it’s not an automatic “no” – it depends on the dose that was given and how much time has passed, etc. In practice, for most patients who have not had any form of radiation, this isn’t an issue. For those few who might have, say, had radiation for a childhood skin hemangioma or another skin cancer before, we’d review those records. If the prior radiation was superficial and limited, sometimes a second course can be done safely, but often if something recurs in a previously radiated field, surgery is the preferred approach. Safety is paramount: skin that’s been radiated is more fragile and has a reduced capacity for repair, so a second radiation could cause non-healing or necrosis. That said, if the prior radiation dose was low or partial, a carefully planned second treatment could be considered by a radiation oncologist in consultation. In general, if you had IG-SRT on an area once, we wouldn’t do it on that same exact spot again if the cancer ever came back there (though as we discussed, that scenario is rare). We would likely opt for surgery in that case. So the guideline is: one definitive radiation treatment per area. If you have a new cancer in an overlapping area that was previously radiated, we examine the feasibility – sometimes we can angle the beams to treat the new lesion while sparing the most heavily previously treated tissue. It’s case-by-case and would involve a radiation oncology input. For Central Oregon Dermatology specifically, if someone had prior radiation elsewhere, we’d coordinate with a radiation oncologist to calculate any additional safe dose.
In summary, while IG-SRT is generally not repeated on the same area that’s gotten a full dose before, each situation is evaluated individually. All previous radiation records near that area would be obtained and reviewed for safety. If it’s deemed too risky, we’d recommend a surgical or other approach. Most patients starting IG-SRT are doing so on a fresh area that hasn’t seen radiation, so it’s not a common limitation. But it’s something to be aware of for long-term planning: we can’t keep using radiation on the same spot over and over.
