Plasma methotrexate levels in patients receiving etoposide, methotrexate, actinomycin, cyclophosphamide, and vincristine (EMA-CO) chemotherapy for trophoblastic neoplasia.

Methotrexate serum levels were measured in eight patients receiving etoposide, methotrexate, actinomycin, cyclophosphamide, and oncovin (EMA-CO) chemotherapy for high-risk and actinomycin-resistant gestational trophoblastic neoplasia. During 41 courses of EMA there were only 3 instances where the level of methotrexate was greater than 9 x 10(-7) M/liter at 24 hr postinfusion. A level higher than this may be associated with subsequent toxicity. Use of postmethotrexate leucovorin rescue should continue, but routine measurement of methotrexate with EMA-CO is unnecessary unless there is compromise of renal or hepatic function.