Friday, July 17, 2009

Endometrial Cancer: Vaginal Brachytherapy vs Whole Pelvis

In this weeks JCO, the first results of the PORTEC 2 trial are published.

In this randomized trial, 427 patients >= 60 years of age with IC grade 1 or 2, IB grade 3, or any age and IIA disease (excluding grade 3 with >50% myometrial invasion, were randomized between vaginal brachytherapy (7Gy q week x 3, or 30Gy LDR) and WPRT (46Gy, 2Gy/day). Note the inclusion criteria; this excludes the IC grade 3 risk group which at the time of the trial design were at too high of a risk not to treat with WPRT.

This is a QOL report, and not surprisingly, VBT comes out on top, particularly with GI toxicities, which let to better social functioning as well.

This is gratifying, as it proves that less is more as far as the adverse events are concerned. Of course, more importantly what is the efficacy data.

This was presented at ASCO 2008. At 3-years vaginal relapse occurred 0.9% in the VBT arm and 2.0% after EBRT (p=0.97), 3-year pelvic relapse was 3.6% and 0.7% (p=0.03), respectively. 3 year distant relapse was 6.4% in the VBT group and 6.0% in the EBRT group (NS). No difference in 3-year OS (90.4% vs. 90.8% p=0.55) and RFS (89.5% vs. 89.1% p=0.38).

So now it's time to step back to the primary study endpoint, which was vaginal relapse, and unfortunately the stats section is a little vague here, probably because this is a QOL report not the clinical results. What it clear is that this was not designed as a non-inferiority trial for pelvic relapse, which to be honest, is what it probably should have been. If you are trying to say that vaginal brachytherapy is safe and as effective as WPRT, then the endpoint should be either pelvic relapse, distant relapse or overall survival. The pelvic relapses were actually significantly worse with VBT, thought the absolute difference was small (~3%). What is important about this is that these patients are essentially unsalvageable, which may eventually show in the OS numbers (though I wouldn't hold my breath due to the power of the study and competing causes of death in this patient population).

That stated, clearly VBT is an option for these patients, and this study, with relatively minor flaws in comparison to others supports the approach.

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