This depends on what we define as “aggressive forms.” If we’re talking about aggressive subtypes of basal or squamous cell carcinoma (for example, morpheaform/infiltrative basal cell, or poorly differentiated squamous cell), IG-SRT can still be very effective, but these cases must be approached carefully. Studies have included various subtypes of BCC and SCC and found high cure rates across the board with IG-SRT. However, traditionally Mohs surgery has been favored for aggressive subtypes to ensure complete margin clearance. Now that IG-SRT offers imaging and high cure rates, it is considered a valid alternative even for these tougher tumors. Clinical research has not shown a significant drop in effectiveness of IG-SRT for, say, morpheaform BCC – the cure rates remain around 98-99% as well. For SCC with perineural invasion or very high-risk features, many times dermatologists will involve a radiation oncologist anyway, even after surgery, because such cases benefit from radiation. IG-SRT could theoretically be used in that context, but often those are managed with a combination (surgery to debulk and then radiation for the margins).
If by “aggressive” we mean tumors that have a higher propensity to metastasize (like a high-risk SCC on the ear or lip), IG-SRT still deals with the local tumor effectively, but it doesn’t address metastasis risk in lymph nodes. For high-risk SCC, sometimes a lymph node evaluation is done surgically – radiation alone wouldn’t cover that. So in that scenario, a combination of surgery and radiation might be indicated.
In summary, IG-SRT is effective at the local treatment of aggressive histologic variants of BCC/SCC (with cure rates still in the high 90s). The only caveat is that some “aggressive” tumors require additional considerations (e.g., checking lymph nodes, or having very close follow-up). The published data, including a large study of 1,632 patients (over 2,900 lesions), showed IG-SRT achieving a 99.3% cure rate, and those lesions included many invasive and high-risk types. This suggests that even aggressive forms respond well to image-guided radiation. So yes, IG-SRT can handle aggressive forms, but each case should be reviewed by the dermatologist to ensure nothing about the cancer’s behavior calls for an alternate or supplemental approach. If IG-SRT is chosen for an aggressive lesion, we follow the patient closely and ensure they’re comfortable with the non-surgical route. In practice, many aggressive basal cells (like morpheaform on the nose) have been cured with IG-SRT with beautiful results. For aggressive SCC, we might be a bit more selective, but it can be done with success as well.
