Chronic pain is a growing problem in healthcare, as patients live longer.

Cancer care is a good example. As a pharmacologist and research scientist, I rarely meet cancer patients in a professional capacity. However, I recently met some suffering from sarcoma, a rare form of bone cancer most common in children and teens.

During our conversation, I was made aware that some of them prefer to manage their pain by smoking marijuana or using cannabis preparations such as cream and oil, rather than taking prescription opioids. The anecdotal evidence for the medicinal benefit of?these preparations?is strong, but there is no scientific evidence for it?from human or animal studies.

That is not through lack of will among researchers. A number of UK laboratories, mine included, have been trying to attract funding from governmental and charitable bodies to research the medicinal use of cannabis in cancer care. But we have had little success.

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There are, I suggest, several reasons for this impasse. One is the disconnect between what scientists know and what the general public believe, resulting from the media emphasis on stories about the psychiatric problems seen in cannabis users.

For the most part, supporters and opponents of medicinal cannabis use agree that such problems will inevitably increase as more and more patients with chronic diseases such as cancer consume cannabis. But that only sharpens the moral responsibility on governments to adopt a funding strategy that will facilitate the development of safer alternatives to smoking marijuana. Only public funding will convince pharmaceutical and biomedical companies to put their full weight behind the development of new cannabis-based and cannabis-imitating drugs, and remove patients from the clutches of illegal drug gangs, or websites offering faulty advice and contaminated preparations.

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The other major problem facing labs such as mine is politics. More and more jurisdictions ¨C including Canada, the Netherlands, Israel and 23 of 50 US states, according to the World Health Organisation ¨C are legalising cannabis use for medicinal purposes. Yet even in these places, cannabis research retains a whiff of disreputability. In countries such as the UK, where marijuana is still illegal, no one wants to be seen condoning the use of a substance bracketed in the same category of harm as heroin.

UK scientists often suggest to me that politicians are reluctant to advocate for the testing of innovative preparations of cannabis out of fear that it could reveal robust evidence for the medicinal benefits of a banned drug, creating pressure for its full legalisation. Such a measure, indeed, was for last week by former Conservative prisons minister Crispin Blunt ¨C but his is likely to prove another voice in the wind unless scientists lend their vocal support, too.

It is the job of those scientists who advise the government on scientific and health-related matters to help politicians overcome their prejudices. The tragedy is that ever since Imperial College London¡¯s David Nutt was sacked in 2009 as chair of the government¡¯s Advisory Council on the Misuse of Drugs, after saying that alcohol and tobacco were more harmful than many illegal drugs, including cannabis, government advisers have failed to advocate for high-risk, high-return investments in cannabis research.

This frustrates many scientists, myself included. Perhaps it is time for the UK government to look at the rules for selection of individuals to these powerful roles, to ensure that their views represent those of the wider research community that they represent.

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But scientists in general need to be more willing to voice their opinions freely, and to present their latest findings even when they don¡¯t amount to irrefutable evidence. The same goes for US researchers into climate change, who are currently in the crosshairs of the Trump administration. Squeamishness about such advocacy is out of date. Modern scientists ¨C especially the more established and media-friendly among them ¨C are obliged to communicate any knowledge, views and research data that might influence public and political opinion.

If scientists self-censor, evidence deficits will be created that will leave journalists and policymakers with no option but to go to less authoritative sources for advice. This can only degrade public dialogue further ¨C and, in the case of medicinal cannabis, leave millions of people in more pain than they potentially need to be.

Aymen Idris is senior lecturer in pharmacology at the University of Sheffield.