Summary— In 45 patients each with a well established and constant pattern of widespread tumour neogenesis following cystodiathermy, early multiple dose adjuvant thiotepa was used in an effort to control the tumours.

The response was good in 32 patients as judged by the reduction in the number of new tumours and by the downgrading and downstaging of new lesions when compared with pre-thiotepa histology. Continuing maintenance therapy was required in the majority but, with the passage of time, the dosage could be progressively reduced, suggesting a cumulative effect of treatment.

Of 13 non-responders, 7 showed evidence of higher than average malignant potential against which thiotepa appears ineffective.

The timing of administration is probably a key factor in success and one which accounts for much of the variation in reported results.