Purpose: This study aimed to optimize the effective doses of mitomycin C, 5-fluorouracil, and their combination on cultivated basal cell carcinoma. Methods: Cultivated basal cell carcinoma and fibroblastic cells were treated with different concentrations of mitomycin C, 5-fluorouracil, and their combination. Cell viability, cell cycle, apoptosis, and expression levels of TP53, CDKN1A, and CDK6 were investigated. The most effective drug with its optimum dosage was administered via multiple intralesional injections to a 65-year-old woman with advanced periorbital nodulo-ulcerative BCC. Results: The concentrations of 0.00312 and 0.312 mg/mL were considered optimum for mitomycin C and 5-fluorouracil, respectively. The mean viabilities of basal cell carcinoma treated with mitomycin C alone and its combination with 5-fluorouracil were significantly less than those of the controls (p=0.002 and p=0.04, respectively). The cell cycle of all the treated basal cell carcinoma groups was arrested in the S phase. The apoptotic rates (p=0.002) of mitomycin C treated basal cell carcinoma were higher than those of the other treated cells, and their TP53 was significantly upregulated (p=0.0001). Moreover, CDKN1A was upregulated, whereas CDK6 was downregulated in basal cell carcinoma treated with either 5-fluorouracil (p=0.0001 and p=0.01, respectively) or the combination of 5-fluorouracil and mitomycin C (p=0.007 and p=0.001, respectively). Basal cell carcinoma lesions were significantly alleviated following mitomycin C injections in the reported patient. Conclusion: Our in vitro results revealed that the effective doses of mitomycin C and 5-fluorouracil on cultivated basal cell carcinoma were optimized. Mitomycin C was more effective in inducing the apoptosis of basal cell carcinoma than 5-fluorouracil and their combination. The intralesional injections of the optimum dose of mitomycin C could be proposed for the nonsurgical treatment of advanced eyelid basal cell carcinoma. RESUMO Objetivo: Otimizar a dose efetiva de mitomicina C, 5fluorouracil e da combinação de ambos em culturas de células de carcinoma basocelular (CBC). Métodos: Culturas de células de células de carcinoma basocelular e de fibroblastos foram tratadas com diferentes concentrações de mitomicina C, 5fluorouracil e combinação de ambos. Além disto, foram investigados a viabilidade celular, o ciclo celular, a apoptose e a expressão dos genes TP53, CDKN1A e CDK6. O medicamento mais eficaz, em sua dosagem otimizada, foi administrado em últiplas injeções intralesionais em uma mulher de 65 anos com carcinoma basocelular nódulo-ulcerativo periorbital avançado. Resultados: A concentração de 0,00312 mg/mL de mitomicina C e a de 0,312 mg/mL de 5fluorouracil foram consideradas as ideias. A viabilidade média das células de carcinoma basocelular tratadas com mitomicina C isoladamente e em combinação foi significativamente menor que nas células de controle (respectivamente, p=0,002 e p=0,04). Todos os grupos de carcinoma basocelular tratados demonstraram interrupção do ciclo celular na fase S. As células de carcinoma basocelular tratadas com mitomicina C mostraram maiores taxas de apoptose (p=0,002) e significativa regulação positiva do gene TP53 (p=0,0001). Além disso, o gene CDKN1A foi positivamente regulado e o gene CDK6 foi negativamente regulado em células de carcinoma basocelular tratadas com 5fluorouracil (respectivamente, p=0,0001 e p=0,01) ou com a combinação de medicamentos (respectivamente, p=0,007 e p=0,001). Injeções posteriores de mitomicina C na paciente em questão levaram à melhora significativa da lesão do carcinoma basocelular. Conclusão: Nossos resultados in vitro otimizaram as doses efetivas de mitomicina C e 5fluorouracil na cultura de células de carcinoma basocelular e mostraram que a mitomicina C tem mais eficácia na apoptose de células de carcinoma basocelular do que o 5fluorouracil e a combinação de ambos. Injeções intralesionais de doses otimizadas de mitomicina C podem ser propostas para o tratamento não cirúrgico do células de carcinoma basocelular avançado de pálpebra.