Rare cancers: let’s take a different approach

Renowned cancer expert Professor Ian Olver has urged a different approach when it comes to finding treatments for rare cancers.

In an editorial published today in the Medical Journal of Australia, the Director of UniSA’s Sansom Institute for Health Research says rare cancers account for 30% of cancer deaths, yet less than 20% of cancer research funding in Australia goes towards these cancers.

Prof Olver says an audit published by Cancer Australia in 2014 showed more than 80% of cancer research funding went to blood cancers and five solid cancers (breast, colorectal, prostate, melanoma and lung cancers), while rare cancers such as pancreatic, ovarian and brain cancer received a much smaller slice of the funding pie.

Rare cancers are defined as those with an incidence of less than six cases per 100,000 population per year.

“If less research is being performed to provide data, and the low incidence of rare cancers makes large randomised clinical trials impractical, there are few evidence-based guidelines regarding rarer cancers to which clinicians can refer,” Prof Olver says.

Prof Olver uses his MJA editorial to pose the question: If we are to prioritise research to improve the outcomes in less common cancers, what needs to be done?

He suggests ovarian cancer is a good example of how approaches to rare cancer treatment need to evolve.

“One feature of common cancers like breast cancer or bowel cancer, where survival has been significantly improved over recent years, is that there is a screening test for early detection,” he says.

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

However, he noted there are similarities between ovarian subtypes and other cancers, which he says will be helpful in identifying targets for new treatments. For example, high-grade serous carcinoma of the ovary shares similarities with triple-negative breast cancers. Drugs used for metastatic breast cancer are now being trialled in patients with ovarian cancer.

“Our approach to clinical trials will need to be different in rare cancers where large randomised trials are impractical,” he says.

“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.”

(Source: University of South Australia, Medical Journal of Australia)