The chance of the same skin cancer coming back in the treated area is extremely low – on the order of 1% or less. IG-SRT’s cure rate is about 99% for basal and squamous cell skin cancers, meaning only around 1 in 100 might recur locally. To put it another way, if 100 people undergo IG-SRT for similar lesions, about 99 of them will have long-term cure at that site.
These statistics come from multi-year follow-ups in studies. For example, one study showed a 5-year local control (no recurrence in 5 years) of 99.5%. Recurrences, when they do happen, usually occur within the first 2-3 years after treatment. It would be quite unusual for a cancer to recur after, say, a decade without any sign in between.
It’s worth clarifying that “recurrence” refers to the same cancer coming back in the exact same spot. We do expect that some patients will get new skin cancers in other spots due to sun damage – that’s not a failure of the treatment, but rather the nature of having a predisposition. So sometimes people might confuse a new lesion nearby as a “recurrence,” but true recurrence is re-growth of the original tumor that was treated.
IG-SRT’s recurrence rates have been shown to be equivalent to, or even slightly better than, those of surgery in some studies. For instance, Mohs might have a 2-5% recurrence at 5 years for some high-risk lesions, whereas IG-SRT reported ~1% in similar populations. Of course, that can vary by tumor characteristics.
So, practically speaking, if you complete IG-SRT, you can be about 99% confident that particular cancer is gone for good. We still monitor because 1% isn’t zero – and if you end up being that rare case, we want to catch it early and manage it (likely with surgery at that point). But fortunately, the odds are strongly in favor of cure.
Do remember that the chance of a completely new skin cancer in a different location is much higher than the chance of recurrence at the treated site. That’s why, as discussed, we emphasize ongoing skin checks: not so much because we expect the treated one to come back, but because you’re at risk for additional cancers elsewhere.
In summary, the likelihood of the treated skin cancer returning is extremely low, on the order of 1% (assuming it was basal or squamous cell and you completed the full prescribed course). IG-SRT offers durable, long-term control of the treated lesion in the vast majority of patients.
