Carotid Stenting, Endarterectomy Both Reasonable After Cervical Irradiation

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Patients who have had prior cervical radiation therapy for cancer or other diseases and require revascularization for carotid stenoses appear to do equally well with carotid endarterectomy (CEA) or carotid artery stenting (CAS), according to a study published online December 29, 2011, ahead of print in Stroke. Radiation therapy has been thought to accelerate the development of severe stenosis, leading to an increased risk of stroke.

Gert Jan de Borst, MD, PhD, of University Medical Center Utrecht (Utrecht, The Netherlands), and colleagues conducted a meta-analysis of 27 studies comprising 533 patients who underwent radiation therapy and subsequent revascularization (361 CAS and 172 CEA). The most common indications for previous cervical radiation therapy were head and neck squamous cell malignancies (ie, primary carcinomas or lymph node metastases of unknown origin).

Expanding the Evidence

At 30 days, the pooled analysis risk estimate for cerebrovascular events was similar between the CAS group (13 studies with 326 patients, 354 procedures) and the CEA group (14 studies with 172 patients, 190 procedures). Follow-up for late outcomes beyond 30 days showed lower rates of cerebrovascular adverse events and restenosis with CEA (table 1).

Table 1. Outcomes

The risk for cranial nerve injury was 9.2% for CEA patients and nonexistent for CAS patients. Reported mortality rates ranged from 0% to 33% for the CAS group and 0% to 44.4% for the CEA group.

According to the study authors, the current review supports the idea that both revascularization options are safe in conjunction with prior cervical radiation, leading to no early deaths and low risk for cerebrovascular events. “On the other hand, [just as] in recent prospective randomized studies in symptomatic patients at normal risk, late clinical events happened more frequently after endovascular repair as compared with CEA,” they write.

But the researchers admit that, like any meta-analysis, the current study has limitations. Among them are:

• Confounding by indication
• Patient selection resulting in differences in outcome favoring CEA, probably because less appropriate surgical candidates (eg, due to previous neck surgery) were excluded
• Small individual sample sizes and lack of reporting specific details
• Inability to distinguish between symptomatic or asymptomatic status as the initial indication for revascularization
• Publication bias

Weighing Risks Difficult at Best

According to Dr. de Borst and colleagues, several studies have suggested that patients with prior cervical radiation are a high-risk group for CEA. But this is controversial, they add, because “the definition was based on theoretical arguments and still no risk stratification for patients undergoing [cervical radiation therapy] exists today.”

Of primary concern regarding CEA in these patients is the risk of cranial nerve injury, which was shown in the meta-analysis to be lower with CAS. Still, they conclude, this risk should probably not contraindicate CEA in irradiated patients.

However, the researchers point out that since they did not know the exact preoperative tissue condition of the treated cervical region, and because they could not reliably analyze details on combined cervical radiation therapy and cervical surgery, this opinion could change. For example, if a patient had wound complications from prior surgery and/or radiation, CAS might be a better alternative to avoid further open surgery in that area.

Ultimately, Dr. de Borst and colleagues conclude: “Due to limited patient data for [cervical radiation therapy]-induced carotid stenosis, we were not able to select the best technique on the basis of particular patient characteristics.”

Study Details

Exact site of irradiation (left vs. right carotid territory) and therapeutic dose were not reported for all patients. The mean interval between cervical irradiation and carotid revascularization ranged from 6.3 to 16.6 years for the CAS group and from 1.7 to 17.0 years for the CEA group. More than half of patients in the CEA group underwent previous neck surgery in combination with cervical irradiation. For the CAS group, this was not clarified.

 

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Source:
Fokkema M, den Hartog AG, Bots ML, et al. Stenting versus surgery in patients with carotid stenosis after previous cervical radiation therapy: Systematic review and meta-analysis. Stroke. 2011;Epub ahead of print.

 

 

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