Discussion
squamous cell neoplasms, squamous neoplasms of the ocular surface, corneal erosion, corneal opacity, toxicity, hyperemia, neoplasms, epiphora, pain, keratitis, CIN, limbic cell deficiency
RECURRENCES, RECURRENCE, CORNEAL EROSION, ALLERGIC REACTION, INTRAEPITHELIAL NEOPLASMS, ADVERSE EVENTS, HYPEREMIA, NEOPLASMS, EPIPHORA, CORNEA, CIN, ADVERSE EFFECTS, KERATITIS, CELL DAMAGE, CARCINOMA IN SITU, EPIDERMOID CARCINOMA
The efficiency of antineoplastic drugs as primary therapy in CIN has been documented by different authors. For instance, Parrozzani R. et al. evaluated the efficacy of topical chemotherapy with 5-FU 1% (10 mg/mL, four times/day for 4 weeks) in 41 patients with CIN. Although no adverse events were reported, the rate of recurrence was 7.3% [To the best of our knowledge, studies about comparative evaluation of available topical chemotherapeutic agents for CIN are limited. In a comprehensive retrospective study, Kusumesh et al. reported the efficacy and safety of MMC versus IFNα2b for the therapy of CIN in 51 eyes of 50 patients. Subjects were treated with either topical IFNα2b (1 million IU/mL, 4 times/day) or MMC 0.04% (0.4 mg/mL, 4 times/ day). In this report, complete response was achieved in 89% of the cases with topical IFNα2b (n = 26) and 92% with MMC (n = 25). The median time to lesion resolution was 3.5 months in the IFNα2b group and 1.5 months in the MMC group, while adverse effects occurred in 12% of patients of the former and 88% of the latter [The need to reduce the risks associated with the surgical treatment of intraepithelial neoplasms has led to the increasingly widespread use of topical chemotherapeutical agents. The direct administration of a drug on the eye avoids the hematoocular barrier, maximizing the drugs’ concentration and limiting its systemic absorption [According to the present study’s results, MMC has the highest rates of adverse effects, with 77.77% of patients reporting at least one., For the IFNα2B group, rates were lower with 50% of the patients,, however, no statistically significant differences were found between both groups.MMC has been used as primary therapy in preference to surgical excision, or as adjuvant therapy in surgical removal either preoperative, intraoperative or postoperative with a 82–100% response rate [Regarding the main reported adverse effects in other studies, conjunctival hyperemia (which may be due to cellular toxicity or allergic reaction), pain, burning sensation, superficial pointy keratitis, epiphora, corneal erosion and corneal opacity have been the most reported, being limbic cell deficiency the most severe one [In the MMC group from the present study, foreign body sensation and dotted de-epithelialization were the most reported adverse effects (66%), this in contrast with other studies where de-epithelialization was reported in 17.4% of patients [On the other hand, topical chemotherapy with immunomodulating agents has gained great attention. Topical IFNα2b has shown to be effective as a single-agent or as an adjunct therapy agent after surgery and since it has not been associated with limbic stem cell damage, it could be an excellent alternative treatment [When comparing adverse effects individually between those presented with MMC and IFNα2b, there was only a significant difference in the foreign body sensation and dotted de-epithelization, which was expected since most of the reported adverse effects are different according to each drug.The possibility of administering the MMC continuously or by cycles gives a difference in the time of resolution of the injury. Some studies report a complete resolution within 28 days of continuous administration [Regarding the response time, there was a statistically significant difference between both groups, with a longer time in patients treated with IFNα2B. In this group, the average response time was 4.7 months; similarly, other studies report a response from 1 month to 9 months of treatment with an average of 3.25 to 3.5 months [It is important to emphasize that the use of topical chemotherapy can be a curative treatment in the management of intraepithelial neoplasms but not for other spectra of ocular surface squamous cell neoplasms, such as carcinoma in situ and invasive epidermoid carcinoma, in which the response to topical treatment is limited [It should be considered that when there is no response to topical chemotherapy, the lesion being faced could already be considered malignant, in which case resection of the same would be indicated [Another option that has been proposed in patients with resistance to topic chemotherapy is to switch to another antineoplastic agent before considering a surgical procedure [In both groups, the decision of management with topical chemotherapy was based on the clinical characteristics of the lesion; however, in all cases, an impression cytology was performed to confirm the diagnosis. The impression cytology was positive in 83% of the patients, similar to what has been previously reported in other studies [Impression cytology is a diagnostic method with high predictability, but in the case of malignant keratinizing neoplasms the possibility of false negatives must be considered due to the scarcity of cells in the sample, so care must be taken in the interpretation in these cases [In 2013, surveys carried out by cornea specialists regarding the standard of choice for the treatment of squamous neoplasms of the ocular surface demonstrated an increase in the use of topical chemotherapeutic agents [For future studies, consideration should be given to conducting a study with a larger number of patients and having a longer-term follow-up in order to assess the possibility of adverse effects that do not occur in this follow-up time and also to determine the presence of later recurrences.