Of patients with a higher histopathological grade in the resected OSSN lesion, LSCD prevalence was higher; this reflects the fact that higher grade OSSN lesions can grow larger and behave more aggressively, thus helping to explain why prevalence is higher in these patients.  Photo: Christine Sindt, OD. Click image to enlarge.

The class of ocular cancers known as ocular surface squamous neoplasia (OSSN) are most commonly found in the limbal region. Consequently, limbal stem cell deficiency (LSCD) is a very real possibility after treatment for the malignancy during follow-up visits.

To investigate the relationship between these factors, Turkish researchers conducted a retrospective study in which clinical and histological data was collected from OSSN patients who were surgically treated. Included was a total of 98 patients (58 male, 40 female) with a mean age of 61 (range 23-86). Investigators found evidence of OSSN involving less than three clock hours in 49.0% of eyes, three to six clock hours in 32.7%, six to nine clock hours in 12.2% and more than nine clock hours in 6.1%. A moderate 36.7% of all patients experienced LSCD after surgery, with severity being mild in 17 eyes, moderate in 11 and severe in eight.

When analyzing their data, the researchers found that LSCD prevalence increased in groups with six or more clock hours of OSSN involvement; however, the affected limbal side (superior, inferior, nasal or temporal) did not display association with LSCD prevalence. LSCD was more likely to develop in both those with a higher tumor stage and those with corneal involvement. Prevalence of LSCD was raised with increasing histopathological grade and the number of clock hours affected by OSSN was found to be an independent risk factor upon multivariate analysis.

Delving further into their results, the authors of the study note that there was a higher proportion of men affected, which reflects current literature. However, men also had higher rates of LSCD development, with reports showing that higher OSSN grades are seen in men. This may be because of a greater proportion of men who have outdoor jobs, thus experiencing more UV-B radiation than women, as UV-B exposure has been found playing a role in both OSSN and LSCD development.

Because of the higher LSCD prevalence observed as limbal area grew larger, as well as high clock hours of limbal involvement significantly affecting LSCD prevalence, the authors argue that “it can be concluded that limbal involvement of more than three clock hours is an independent risk factor of LSCD in surgically treated patients with OSSN.”

Perhaps more importantly, the authors add that “understanding the variables that contributed to emergence of LSCD following OSSN surgery is crucial since it helps the risk-based modification of treatment.”

While OSSN is still treated surgically, there is now topical interferon alpha treatment, demonstrating cure rates in one group of 98% at five years and 96% at 10 years without limbal damage. What’s more this topical option has demonstrated efficacy in partial limbal stem cell deficiency cases. Even greater is that treatment failures have been effectively addressed via medical interventions with low risk of adverse effects on healthy tissue. Along with the fact that high probability of recurrence is present when initial lesion is not completely excised, the investigators believe “when these reports are considered in conjunction with the findings of this study, a strong argument emerges in favor of switching to medical treatment of OSSN.”