A vitamin A derivative that could slash the risk of breast cancer recurrence in younger women, could find a role in patients who do not respond to anti-oestrogen therapy, a new study has suggested.

Investigators at the European Institute of Oncology in Milan found that fenretinide halved the risk of breast cancer returning in women aged 40 or younger, according to a report in the Annals of Oncology.

The team studied 1,739 women for a median of 14.6 years. Premenopausal participants who received fenretinide were 38% less likely to see their cancer return after surgery, compared to patients in the control group.

Among patients aged 40 or younger, the risk-reduction figure rose to 50%. In post-menopausal women there was a slight increased risk of recurrence, although this was not statistically significant.

“The current analysis confirms and further extends the notion that the protective effect of fenretinide occurs exclusively in premenopausal women aged 55 years or younger," said Professor Umberto Veronesi, who led the study.

Breast cancer is much less likely to occur in younger women. The researchers note, however, that when the disease does strike this age group it tends to be very aggressive; hence the need for better drugs.

In addition, fenretinide appeared to prevent the return of oestrogen receptor-negative cancer - the type against which tamoxifen has no effect. Researchers also think that fenretinide might avoid some of the side-effect pitfalls of the new aromatase inhibitors, which are supplanting tamoxifen in a number of breast cancer indications and include AstraZeneca’s Arimidex (anastrozole), Novartis’ Femara (letrozole) and Pfizer’s Aromasin (exemestane).

Prof Veronesi said that there were limitations in the trial design. Around 40% of participants in the original trial were treated at several different centres, and their follow-up became sporadic after the seventh year.

However, given the impact the drug appeared to have in younger patients, experts called for immediate follow-up work.

“This tantalising observation...is of great interest," said Dr Kathy Pritchard, chairwoman of the breast cancer site group at Toronto Sunnybrook Regional Cancer Center, in accompanying editorial.

Prof Veronesi and his colleagues have already begun a trial of fenretinide with low-dose tamoxifen in premenopausal women at high risk. Meanwhile, the US National Cancer Institute has trials of the drug ongoing in a number of cancers, including neuroblastoma, ovarian and prostate cancer and haematological malignancies.