The researchers added: "Sustained marijuana use may increase the risk for testicular cancer."
They estimated that long-term users of cannabis were 36 per cent more likely to be diagnosed with the potentially-fatal condition.
This was compared to similar males who did not use the drug.
It has been suggested by some groups campaigning for cannabis to be legalised in the UK that it can help fight cancer.
As well as smoking cannabis, other known risk factors include having undescended testicles or a family history of the disease.
According to the NHS: "Typical symptoms are a painless swelling or lump in one of the testicles, or any change in shape or texture of the testicles.
"The swelling or lump can be about the size of a pea, but may be larger.
"Most lumps or swellings in the scrotum are not in the testicle and are not a sign of cancer, but they should never be ignored."
Other symptoms include an increase in the firmness of a testicle, a difference in appearance between one testicle and the other, a dull ache or sharp pain in your testicles or scrotum which may come and go, and a feeling of heaviness in your scrotum.
It is a relatively rare condition, and affects just one per cent of all cancers that occur in men.
While it is rather uncommon overall, it is the most common type of cancer diagnosed in men between men aged 15 to 49.
Indeed, half of those who are diagnosed each year with the cancer are below the age of 35.
It is also more likely to occur in white men than those from other ethnic groups, however scientists are not yet sure why.
There has also been a doubling in cases in the UK since 1970s - reasons for which also remain unclear.
According to the NHS: "Testicular cancer is one of the most treatable types of cancer, and the outlook is one of the best for cancers.
"In England and Wales, almost all men (99 per cent) survive for a year or more after being diagnosed with testicular cancer, and 98 per cent survive for five years or more after diagnosis."
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