MTX with Leucovorin rescue as a single drug treatment for G. T. T. causes complications, is usually adequate but drug resistance occasionally occurs. This is a report of a study done in 80 consecutive patients (pts)treated with MTX between 1983
and
1991
at Il Sin Christian Hospital, Pusan to see if predictive factors for the development of the drug resistance could be identified. According to the 1983 WHO prognostic score 72 pts were low risk, 7 medium and high risk. Durg resistance developed in
22/72
pts(30.6%) low risk pts and in all of the medium and high risk pts.
Factors analysed as possible predictive factors for developing drug resistance were total prognostic score, the separate factors of the prognostic score, factors related to the preceeding mole, size of uterus at start of chemotherapy and factors
related
to previous fertility.
The most significant factors associated with a high risk of resistance were WHO prognostic score 5 and over, 8/8 pts(100%), HCG titer>10E4 mIU/ml, 12/15 pts(85.7%), tumor size 3 cm and over, 8/8 pts(100 %), and less commonly a preceeding non
molar
pregnancy 2/3 pts.
Among the 8 medium & high risk pts the preceeding preg. Was non molar in 2 pts and of the remaining 6 pts all had at least 1 of the 2 predictive risk factors and 5/6 had both of these factors. These results emphasise the reliability of the WHO
prognostic score in selecting pts who need multiple therapy and also that MTX alone is usually inadequate in these pts.
Among the low risk pts if either or both of these factors were present, 80% of pts (8/10)developed drug resistance compared to 22.6% (14/62) if neither factor was present.
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