The approach to clinical trials needs to be different in rare cancers where large randomised trials are impractical, says Professor Ian Olver in an editorial published today in the Medical Journal of Australia.

He wrote that ovarian cancer was a good example of how approaches to rare cancer treatment needed to evolve.

The heterogeneity of ovarian cancer suggests that a population screening test based on a panel of biomarkers will be difficult to achieve, he said.

Proof of principle that a targeted therapy is effective could be achieved with a small efficacy trial or case series.

Refinements could be made by interrogating large international digital databases of patient records when the drug is adopted into practice, he said.

Other approaches could involve using Bayesian analysis to determine whether the numbers of patients available to be entered in a trial would deliver useful clinical guidance.

“Reassessing research into cancers or cancer subtypes classified as histologically rare may involve finding molecular and genetic similarities across a range of cancers, which suggest that a targeted therapy in one may be successfully trialled in another”.

“This requires national and international collaboration and linking datasets from biobanks and registries” he concluded.