Treatment of 9 conjunctival cell carcinoma in situ (CIN) with mitomycin C eye drops under cytological and DNA-image-cytometric control

Background: Conjunctival intraepithelial neoplasia (CIN) is a frequent conjunctival tumor. Following excision alone recurrences are frequent. An effective postsurgical recurrence prevention is therefore highly desirable. In this study we aimed to evaluate the effectivity of postsurgical chemotherapy of conjunctival squamous cell carcinoma in situ (CIN) with mitomycin C eyedrops. We introduced the otherwise established diagnostic tools of cytology and DNA-image-cytometry to the diagnosis and therapy-monitoring of CIN. Patients and methods: We treated 9 patients with GIN. For diagnosis the results of cytology and cytometry of presurgically obtained brush smears were compared with the histologic evaluation of the excised tissue. After surgery, we administered topical chemotherapy with mitomycin C eye drops 0.02% (MMC). Conjunctival brush smears were again evaluated by cytology and DNA-image cytometry for postsurgical therapy monitoring. Results: The clinical diagnosis of CIN was fully confirmed by cytology, DNA-image-cytometry and histology respectively in 7 patients. In one patient, the results of the applied diagnostic methods differed in results: Histologic evaluation indicated a moderate dysplasia but DNA-image-cytometry showed significant DNA-aneuploidy unequivocally indicating neoplasia like squamous cell carcinoma. In another patient the preoperatively obtained conjunctival brush smears could not properly analyzed by cytometry but clinical diagnosis was confirmed by histology. MMC-therapy was well tolerated except for a self-limited conjunctivitis. A complete remission of CIN was obtained in 8 of 9 patients (89%) who were free of CIN recurrences during a follow-up period of 27.2 months (11-48). Only one patient suffered from a recurrence 14 months after surgery and after 2 MMC-cycles. Conclusion: Adjuvant topical mitomycin C appears to be effective in the prevention of recurrences of conjunctival CIN after surgical removal. Our results indicate that at least 4 cycles of topical MMC are required to prevent local recurrences in the long term. Cytology and DNA-image cytometry are highly sensitive and specific methods for diagnosis and therapy monitoring of conjunctival squamous cell carcinoma in situ (CIN).