Author: Hibba Quhill (United Kingdom)
Co-authors: Hibba Quhill, Sachin Salvi, Ian Rennie, John Yianni, Matthias Radatz, Paul Rundle
Purpose
Stereotactic radiosurgery (SRS) is an effective treatment for uveal melanoma used widely in Europe, offering excellent local tumour control rates and eye preservation. Its efficacy relies upon accurate localisation of the radiation-dose to the tumour, which is challenging in a mobile eye. Various methods of globe immobilisation have been used; practice at the National Centre in the United Kingdom is local anaesthetic (LA) block with or without suturing of two extraocular muscles. Suturing is employed to limit posterior globe movement during inevitable anaesthetic reabsorption. Some studies have shown that the addition of muscle suturing to LA improves absolute globe immobilisation, as measured by comparing pre- and post-procedure radioimaging. However, controversy and debate exist regarding the clinical relevance of this observation, as no studies have published data comparing immobilisation technique with clinical outcomes. Ocular oncologists differ in their choice of immobilisation technique, even within our national centre. This work was designed to answer this debate.
Setting/Venue
The National Centre for Stereotactic Radiosurgery and the Sheffield Ocular Oncology Service, Royal Hallamshire Hospital, Sheffield, United Kingdom.
Methods
We performed a retrospective review of all cases that underwent gamma knife stereotactic radiosurgery for uveal melanoma over a 10-year period (May 2008 to May 2018) at our national centre, with at least 24 months follow up. Data collected for each patient included demographic information, operating ophthalmic surgeon, the globe immobilisation technique used, and follow up duration. The outcomes assessed were primary treatment failure of SRS, local recurrence of melanoma, secondary enucleation and all-cause death rate. At the single National Centre, the three operating oncologists differed in their choice of immobilisation technique: surgeon X always employed retrobulbar LA plus muscle suturing; surgeon Y, prior to 2013, always used peribulbar LA plus muscle suturing, but changed his practice to peribulbar LA alone in all cases; surgeon Z only used peribulbar LA without sutures. The decision as to suture or not depended entirely on operating surgeon preference, the allocation of which was based on organisational convenience not patient-specific factors. Patients who received LA plus muscle suturing were grouped together (Group A) and compared to those who were given LA alone (Group B).
Results
290 eyes in 290 patients were treated during the inclusion period; 118 patients in group A (sutured) and 172 patients in group B (not sutured). The length of follow-up was significantly longer in group A than group B (92 months cf. 53 months, p<0.001). This was a result of the surgeons operating as per their preferences: surgeons who sutured were the longest-serving, and surgeon Y, who performed 233 of the 290 cases, stopped suturing in 2013. This skewed the follow-up duration between the groups. There were no cases of primary treatment failure in either group. With a minimum of 24 months follow-up, only 3 patients experienced tumour recurrence (1 in group A and 2 in group B). There was no significant difference between the two groups with regards to recurrence, enucleation and all-cause death rate, though there was a trend towards a higher secondary enucleation rate in group B. Secondary enucleation was only performed for complications of radiotherapy (e.g. painful blind eye due to rubeosis) and not local recurrence, which was treated by other means.
Conlusions
In this retrospective observational cohort study, no significant difference in clinical outcome was identified between those patients sutured (group A) and those not sutured (group B) during globe immobilisation. This suggests that although extraocular muscle suturing may enhance globe immobilisation in absolute terms, this does not translate to altered clinical outcomes. Limitations of this study include the patients not being randomised between groups: the decision to suture, or not, was made according to the operating ophthalmic surgeon’s preference. This led to a significant difference in follow-up duration between the two groups, which must be considered when interpreting the results. It is possible that further recurrences, enucleations or deaths could be identified with longer follow-up, meaning that significant differences in clinical outcomes could occur. Indeed, there is a trend towards a higher secondary enucleation rate in group B, which also has the shorter follow-up. That being said, secondary enucleations are not related to eye movement leading to inaccurate targeting of the tumour, and therefore are unlikely to be due to globe immobilisation technique. Further study is needed examining clinical outcomes with longer follow-up to more clearly answer the debate.
Financial Disclosure
The authors have no financial relations to disclose and no conflicts of interest.
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