Theresa A Lawrie, Mo'iad Alazzam, John Tidy, Barry W Hancock, Raymond Osborne

This is the second update of a Cochrane review that was first published in 2009, Issue 1, . Gestational trophoblastic neoplasia (GTN) is a rare but curable disease arising in the fetal chorion during pregnancy. Most women with low-risk GTN will be cured by evacuation of the uterus with or without single-agent chemotherapy. However, chemotherapy regimens vary between treatment centres worldwide and the comparable benefits and risks of these different regimens are unclear. To determine the efficacy and safety of first-line chemotherapy in the treatment of low-risk GTN. We electronically searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and Embase in September 2008, February 2012, and January 2016. In addition, we searched online trial registers for protocols and ongoing trials. For the original review, we included randomised controlled trials (RCTs), quasi-RCTs and non-RCTs that compared first-line chemotherapy for the treatment of low-risk GTN. For this updated versions of the review, we included only RCTs. Two review authors independently assessed studies for inclusion and extracted data to a pre-designed data extraction form. Meta-analysis was performed using the random-effects model. We included seven RCTs (667 women) in this updated review. Most studies were at a low or moderate risk of bias and all compared methotrexate with actinomycin D. Three studies compared weekly intramuscular (IM) methotrexate with bi-weekly pulsed intravenous (IV) actinomycin D (393 women), one study compared five-day IM methotrexate with bi-weekly pulsed IV actinomycin D (75 women), one study compared eight-day IM methotrexate-folinic acid (MTX-FA) with five-day IV actinomycin D (49 women), and one study compared eight-day IM MTX-FA with bi-weekly pulsed IV actinomycin D. One study contributed no data. Moderate-certainty evidence indicates that actinomycin D is probably more likely to lead to primary cure than methotrexate (risk ratio (RR) 0.65, 95% confidence interval (CI) 0.57 to 0.75; six trials, 577 participants; I(2) = 26%), and first-line methotrexate treatment is probably more likely to fail than actinomycin D treatment (RR 3.55, 95% CI 1.81 to 6.95; six trials, 577 participants; I(2) = 61%; moderate-certainty evidence) Low-certainty evidence suggests that there may be little or no difference between methotrexate and actinomycin D treatment with respect to nausea (four studies, 466 women; RR 0.61, 95% CI 0.29 to 1.26) or any of the other individual side-effects reported, although data for all of these outcomes were insufficient and too inconsistent to be conclusive. Low-certainty evidence suggests that there may be little or no difference in the risk of severe adverse events (SAEs) between the groups overall (five studies, 515 women; RR 0.35, 95% CI 0.08 to 1.66; I² = 60%); however, the direction of effect favours methotrexate and more evidence is needed. Furthermore, evidence from subgroup analyses suggests that actinomycin D may be associated with a greater risk of SAEs than methotrexate (low-certainty evidence). We found no evidence on the effect of these treatments on future fertility. Actinomycin D is probably more likely to achieve a primary cure in women with low-risk GTN, and less likely to result in treatment failure, than a methotrexate regimen. There may be little or no difference between the pulsed actinomycin D regimen and the methotrexate regimen with regard to side-effects. However, actinomycin D may be associated with a greater risk of severe adverse events (SAEs) than a methotrexate regimen. Higher-certainty evidence is still needed on treating low-risk GTN and the four ongoing trials are likely to make a significant contribution to this field. Given the variety of treatment regimens, findings from these trials could facilitate a network meta-analysis in the next version of this review to help women and clinicians determine the best treatment options for low-risk GTN.