PIONEER: a randomised Phase II trial in early stage, operable ER+ breast cancer patients - new publication in 'Nature Reviews Cancer'

News source: 
Anticancer Fund

A new paper in the journal Nature Reviews Cancer, ‘Deciphering the divergent roles of progestogens in breast cancer’, Carroll et al, outlines the complex role of progestogens in ER+ breast cancer. The field has been complicated by widespread controversy over the role of the Progesterone Receptor in breast cancer, and the wide range of different compounds called progestogens, both natural and synthetic, that can activate it. A persistent fear has been that some agents may be linked to cancer-onset or can increase cancer cell proliferation. The new paper reviews the evidence for this pro-cancer effect for different classes of progestogen, and shows that some agents, particularly megestrol acetate, have clinically significant anti-cancer effects. Furthermore, the paper makes clear that many women currently do not adhere to anti-estrogen therapy due to associated side effects, particularly hot flushes, thereby decreasing their chance of survival.

Megestrol acetate has been shown to reduce hot flushes in 85% of women, potentially improving treatment compliance with their existing anti-estrogen therapy and hence improving survival independent of its other anti-cancer actions. The anti-cancer properties of megestrol acetate and the effects in reducing hot flushes are key mechanisms behind the PIONEER trial, funded by the Anticancer Fund. PIONEER is a randomized controlled trial in the UK which will investigate the combination of megestrol acetate with letrozole, a type of anti-estrogen treatment called an aromatase inhibitor, in post-menopausal women with breast cancer. The trial will assess whether two weeks of megestrol acetate treatment, alongside the standard letrozole treatment, can reduce the growth rate of cancer cells. If successful, PIONEER will be followed by a much larger randomized trial which will use megestrol acetate as a long-term addition to standard anti-estrogen therapies.


Source: (abstract only)