Campaign website has scant details of what he did from 1963 to 1981

In article about health he cited claim that lack of sex was linked to cancer

Sanders wrote for alternative paper in Vermont, state he now represents

New York Times has published some of his radical 1960s and 70s journalism

Bernie Sanders, the Democrat longshot for the White House who is packing stadiums as he campaigns, once suggested a lack of sex could cause cancer.

The 73-year-old senator was a self-styled 'revolutionary' who occasionally wrote for a radical newspaper in the 1970s when he expressed the view.

He also wrote in praise of Fidel Castro's Cuba, accusing the 'American media' of inaccuracy.

The contents of his journalism were revealed by the New York Times, and were published in The Vermont Freeman.

The now defunct newspaper was published at a time that Vermont had become a haven for people who wanted to challenge the orthodoxy - among them Sanders.

The New York Times reported that he was only a sporadic contributor to the paper, which drew its writers from left-wing circles in the state.

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Campaigner: Bernie Sanders speaks on the first day of the Committee on Racial Equality Sit-In, January 1962

Revolutionary: Sanders styled himself as a revolutionary and became America's first socialist mayor in 1981 in Burlington, Vermont, where he was photographed in city hall.

One of his subject was health and he wrote a number of articles - among them one which cited approvingly research published in a journal called Psychosomatic Medicine.

It suggested that cancer was linked to psychological well-being, and that factors which could cause it included unresolved hostility towards your mother, hiding aggression behind 'a facade of pleasantness - and not enough sex.

'Sexual adjustment seemed to be very poor in those with cancer of the cervix,' Sanders wrote, quoting the journal.

Such findings do not form part of mainstream medical thinking. Research has suggested a link between regular sex and a lower risk of prostate cancer in men - but for physiological not psychological reasons.

Sanders' interest in health now is a campaign promise to guarantee health care to all Americans as a right.

The now White House hopeful also wrote about Cuba. An article published in 1969 to mark the tenth anniversary of the Cuban revolution which brought Castro to power.

'The American press and mass media have been stepping up their usual distorted and inaccurate reporting,' wrote Sanders.

Castor never allowed any press freedom and he marked the tenth anniversary of coming to power by asking people to accept a cut in ther sugar ration and postponing the New Year 1970 holiday.

Sanders has since been outspoken in his support for an end to sanctions against Castro's regime, which finally happened earlier this year.

The discovery of Sanders' views comes as his popularity appears to soar among Democrats in key primary states.

Democratic presidential candidate Bernie Sanders is gaining on Hillary Clinton, and fast. His rapid rise was no more keenly felt than when he packed the Veterans Memorial Coliseum in Madison, Wisconsin, last night, filling its 10,000 seats - a feat for any candidate, and especially a long-shot

Two months after his informal announcement outside the Senate to a handful of reporters, Sanders is earning the type of grassroots support that Clinton has been struggling to attract

This week he packed a 10,000-seater venue while Hillary Clinton - the frontrunner - struggled to fill seats.

With no major donors backing him, no pre-existing campaign infrastructure and as a self-described socialist, Sanders has defied expectations with his popular appeal.

The Times article was published shortly after a local newspaper in Vermont disclosed that two men had been seen in local archives appearing to be looking into Sanders' past and that one was wearing a t-shirt for a Clinton ally's campaign - suggesting the Clinton camp may be looking to discredit Sanders.

How seriously Clinton takes a Sanders challenge is unclear. She has never used his name in public, and remains far ahead in polls.

But Sanders this week claimed he will win the White House - which would make him America's first self-described socialist president.

'We are going to win New Hampshire. We're going to win Iowa, and I think we're going to win the Democratic nomination, and I think we're going to win the presidency,' Sanders told ABC News.

He added that even though he would be 75 on Election day 2016, his background as a long distance runner meant that he is 'blessed with endurance and health'.

'I don't think I've taken a day off because of sickness in several years,' the senator added.

The Vermont senator's rapid rise was no more keenly felt than when he packed the Veterans Memorial Coliseum in Madison, Wisconsin, earlier this week, filling its 10,000 seats - a feat for any candidate, and especially a long-shot like Sanders.

Missing years: Sanders' own political biography on his campaign website is sketchy about what he did in the late 1960s and early 1970s but it is now known he wrote occasional articles, one linking cancer to a lack of sex

'Tonight we have made a little bit of history,' the white-haired Sanders said at a podium positioned between Wisconsin and United States flags at the outset of his speech before a boisterous crowd.

'Tonight, we have more people at any meeting for a candidate of president of the United States than any other candidate.'

Sanders' crowd broke the record for 2016 candidates, an embarrassing blow to Clinton, who is struggling to fill stadiums.

Whether he addresses his past interest in revolution - one article he wrote was titled 'The Revolution Is Life Versus Death' - remains to be seen.

His own website is sketchy about those years. It notes that he saw the Rev Dr Martin Luther King speak in Washington DC in 1963, says that 'he moved to Vermont where he worked as a carpenter and documentary filmmaker' and in a timeline of the 1970s lists claims that he became Burlinton mayor in 1971 - which actually happened in 1981.