The age range of patients of OSSN in this study ranges from 15 to 84 years with the mean age of 44.5 which is in accordance with other studies.[1] However, the HIV positive individual and patients with systemic illness like Xeroderma Pigmentosum are seen to present at a younger age.[11] The bilateral cases in this study were of Xeroderma Pigmentosum and both presented at a relatively young ages of 19 and 22 years. None of our patients were positive for HIV.
Slight male preponderance was seen with M:F ratio 1.3:1, which is similar to other studies.[1, 21, 22] It has been observed that male gender is a likely risk factor for higher preponderance as they are more commonly employed in professions involving outdoor work thereby leading to increased exposure to UV-B rays which is a known risk factor for development of OSSN.[1, 21, 22, 23, 24] The majority of lesions in our study occurred in nasal and temporal areas which are exposed to the highest amount of UV-B radiation, which is similar to other studies [6, 23, 24]. Most of our patients were also from hilly regions which has more UV-B exposure as compared to terai/flat region, which supports UV-B exposure as a risk factor OSSN. Mountain region with the most UV-B exposure among the three regions in Nepal is less populated which resulted in less patient from that area. Due to these factors we presume our findings support the fact that UV- B rays are strongly associated with the development of OSSN. However, the data on exposure was unavailable in our data set so this association is just speculative.
Most of the cases (94.6%, 35 patients) showed unilateral involvement whereas there were 2 cases with bilateral involvement. Both the bilateral cases in this study were known cases of XP and it has been well documented that patients with Xeroderma Pigmentosa are prone to develop OSSN and progress rapidly owing to the defective DNA repair. [6, 9, 19]
Topical therapies for OSSN has rapidly grown in popularity in recent years, yet surgical excision remains the most important treatment option in the management of OSSN, as it provides a pathological diagnosis, differentiates it from masquerading lesions, decreases the tumor load and can diagnose invasion, which would necessitate a different treatment approach. Majority of the patients in our study underwent wide excision with cryotherapy (with autologous graft or with AMG). Some had excision of the OSSN due to unavailability of the cryotherapy at the given moment. All the patients with evidence of tumor cells in any margins were put on adjuvant chemotherapy as it has shown to decrease the recurrence. 2 patients underwent exenteration due to extension of the tumor to the tenon and sclera.
Various factors for tumor recurrence include systemic illness like HIV and XP, presence of persistent ocular surface irritating factors, involvement of the tarsus and positive surgical margins, of which the latter two were found to be the strongest predictors for clinical recurrence.[23] Recurrence rates following excision of OSSN alone range from 5–69%[25–28] and after excision combined with cryotherapy range from 7.7–11.5%.[29–30] The lower rates of recurrence are seen in cases where the margins of the excised specimen were free of tumor cells and adjuvant chemotherapy has been used and the higher rates when dysplastic tissue was left at the surgical margins and in more advanced lesions.[25, 26, 27, 28, 31]Therefore, it is very important to ensure clear surgical margins. Our study had 12.8% recurrence rate which is similar to other studies. [31, 32] Though our data on recurrence is low, we observed that 3 out of 5 recurrence were managed initially with excision biopsy only and 2 were managed with excision biopsy with cryotherapy with AMG. Similarly, 4 out of 6 recurrences had histological grading CIN III to SCC and 5 out of 6 cases with recurrence had positive surgical margins for tumor cells. So, the higher grades of OSSN in our patients and lack of cryotherapy could be the factors for the higher rate of recurrence in this study but the major factor can be attributed to the involvement of margins. The mean duration to recurrence in our study was 9 months following the completion of the treatment which was similar to other studies that state most recurrence took place within 2 years after primary excision. [33, 34] Consistent with a study done in UK,[32] age and sex of the patient didn’t show any significant role in the recurrence.