Regression of endometriosis following shorter treatment with, or lower dose of danazol: Comparison of pre‐ and post‐treatment laparoscopic findings in the Scandinavian multi‐center study

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Abstract
One hundred and sixteen patients with laparosco‐pically confirmed primary or recurrent endometriosis were treated with danazol, either 600 mg daily for 4 months (group A, n = 76) or 600 mg daily for the first 2 months, followed by 400 mg daily for an additional 4 months (group B, n = 40). The only surgery performed before treatment was biopsies, resection of endometriomas 23 cm and/or adhe‐siolysis. The extent of endometriosis before and after treatment was established laparoscopically and recorded by means of a modified AFS record as mean additive diameter of implants (mean ADI) in millimeters. This provided a uniform and reproducible quantitative registration for each type and location of endometriotic implant.Both treatment schemes resulted in a highly significant (p<0.001) reduction of endometriosis, by 79 and 89% in groups A and B, respectively. However, the reduction in mean ADI was significantly greater (p< 0.025) in group B which had been treated for a longer period. Morevoer, the proportion of patients with extensive pre‐treatment lesions (mean ADI 240 mm) was significantly greater in this group.Active residual endometriosis was found in 21 and 17.5% in groups A and B, respectively. These patients had significantly more extensive endometriosis before treatment. The regression of endometriotic implants was independent of type and/or location, i.e. superficial or scarred; peritoneal, ovarian, or tuba]. There was no apparent correlation between the quantitative reduction of endometriosis and amenorrhea versus occasional spotting and/or irregular menstruations.Despite the marked reduction of endometriotic tissue following both treatment schemes, only 4 months of treatment with 600 mg daily appears to be too short a period to ensure elimination of endometriosis, leaving a number of small residues at the end of treatment. Six month's treatment according to schedule B produced a significantly greater reduction in endometriotic tissue, but lowering of the dose to 400 mg daily after 2 months was associated with a significant increase of irregular vaginal bleeding.Although the choice of danazol dose and duration of treatment in endometriosis depends on the objective and approach in the individual case, the authors do not feel confident in recommending less than 600 mg daily for 6 months, if a high probability of complete resolution of all endometriotic implants, other than endometriomas, is desired.