Plaque Neovascularization and Prior Neck Radiotherapy
What is the effect of radiotherapy (RT) on intraplaque neovascularization (IPN) in human carotid arteries?
In this cross-sectional study, patients who had undergone unilateral RT for head and neck cancer ≥2 years previously underwent B-mode and contrast-enhanced ultrasonography (CEUS) of both RT-side and non-RT side carotid arteries. Presence of IPN during CEUS was judged semi-quantitatively as grade 0 (absent), grade 1 (present but limited to plaque base), or grade 2 (extensive and noted within plaque body).
Of 49 patients studied, 38 (78%) had plaques. The number of plaques was significantly greater in the RT versus the non-RT arteries. Overall, 48/64 (75%) of all RT-side plaques had IPN vs. 9/23 (39%) of the non-RT side plaques (p = 0.002). Amongst patients with plaques, IPN was present in 81% patients with RT-side plaques vs. 41% patients with non-RT side plaques (p = 0.004). Grade 0 IPN was significantly more common in patients with non-RT side plaques (25% vs. 61%, p = 0.002), whereas grade 2 plaques were more common on the RT side (31% vs. 9%, p = 0.03). The only clinical variable that predicted presence or absence of IPN was RT laterality.
The authors concluded that a significant association exists between RT and presence and extent of IPN.
This study reports that IPN is significantly increased in plaques within arteries exposed to RT compared to arteries that did not receive RT. Furthermore, these findings were independent of all clinical variables and the only variable associated with presence of IPN was RT laterality. These results appear to suggest that the atherosclerotic plaques of radiation vasculopathy may demonstrate increased vulnerability and this may help to explain the greater risk of cerebrovascular events in this patient population. Based on available data, it would seem reasonable to regularly monitor carotid arteries, especially in patients with pre-RT atherosclerotic plaques.
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