[Methotrexate in gynecologic oncology]

Methotrexate produced the first remission in leukemia and the first cure of a solid tumor, choriocarcinoma. Methotrexate tightly binds to dihydrofolate reductase (DHFR), blocking the reduction of dihydrofolate to tetrahydrofolic acid, the active form of folic acid. Methotrexate also directly inhibits the folate-dependent enzymes of de novo purine and thymidylate synthesis. Resistance to methotrexate may develop as a result of elevated DHFR activity or defective transport of methotrexate into malignant cells. Increased DHFR enzyme levels may also result from amplification of the DHFR gene, which is now clinically significant in selected patients. Methotrexate is an active drug in the first-line treatment of gestational trophoblastic disease (GTD) and in metastatic squamous cell carcinoma of the cervix. Since the introduction of methotrexate chemotherapy for malignant GTD, most hospitals have reported almost 100% cure rates for patients with nonmetastatic disease using single-agent regimens. Patients with low-risk metastatic disease have been treated with methotrexate and folinic acid and over 50% complete remission rates have been reported. Patients with metastatic GTD who had one or more high-risk factors benefited from initial multiagent chemotherapy, rather than waiting for acquisition of drug-resistance to single-agent therapy to start multiagent treatment. Using multiagent combination chemotherapy such as MAC (methotrexate, actinomycin D, cyclophosphamide) or EMA-CO (etoposide, methotrexate, actinomycin D and cyclophosphamide, vincristine), most investigators have reported remission in approximately 60 to 80% of patients with high-risk metastatic GTD. Although the role of chemotherapy in carcinoma of the cervix has been limited for several reasons, trial of combination chemotherapy including methotrexate has been reported. However, it is still impossible to draw definite conclusions as to whether methotrexate combined with another clearly active drug may yield a superior response rate and survival.