Men who put on 2st (12.7kg) before turning 30 are 27% more likely to die from prostate cancer in old age than those who maintain their teenage weight, early research suggests.
A decades-long study into more than 250,000 Swedish men indicated there was a strong link between men gaining weight across their healthiest years and developing prostate cancer.
The analysis suggests those who gained at least half a kilogram a year (1.1lbs) from 17 to 60 had a 10% greater risk of aggressive prostate cancer and a 29% greater risk of fatal prostate cancer.
But gaining weight more steeply puts you at a similar risk. A man putting on 13kg (28lbs) between the ages of 17 and 29 is associated with a 13% increased risk of aggressive prostate cancer and a 27% increased risk of fatal prostate cancer.
The findings, which are yet to be peer reviewed, were part of the Obesity and Disease Development Sweden study from 1963-2014. Researchers analysed the data of Swedish men who had had their weight measured at least three times between the ages of 17 and 60.
Dr Marisa da Silva, of the department of translational medicine at Lund University, said: “Knowing more about the factors that cause prostate cancer is key to preventing it.
“We do not know if it is the weight gain itself or the long duration of being heavier that is the main driver of the association that we see. Nevertheless, one must gain weight to become heavier, so preventing a steep increase in weight in young men is imperative for the prevention of prostate cancer.”
Of the 258,477 Swedish men who had taken part of the study, 23,348 participants were diagnosed with prostate cancer, with an average age at diagnosis of 70 years, with 4,790 men dying from the disease.
With more than 1.4m cases diagnosed every year, prostate cancer is the most common cancer occurring in men. In the UK, one in six men are diagnosed with the disease in their lifetime.
Almost 12,000 men a year die from the disease in the UK, and African-Caribbean men in the UK are almost twice as likely to die from the disease compared with their white counterparts.
Although many prostate cancers are slow-growing and may not cause a man harm during his lifetime, with eight in 10 men diagnosed in England living for at least 10 years after diagnosis, others can be more aggressive and harder to treat.
Previous research has suggested a strong link between excess body fat increases and the risk of aggressive and fatal prostate cancer.
Da Silva said: “Previous research has implicated elevated concentrations of insulin-like growth factor-1 (IGF-1), a hormone that is involved in cell growth and development, with an increased risk of prostate cancer.
“Levels of this hormone are raised in people with obesity and a steep increase in weight may fuel this elevation and the development of the cancer.”
Simon Grieveson, assistant director of research at Prostate Cancer UK, said: “Several studies have indicated a possible correlation between being overweight and aggressive prostate cancer, and this study builds on those by suggesting that weight gain earlier in life is associated with an increased risk of dying from the disease.
“While these results are intriguing, more research is needed to fully understand the biological link between obesity and prostate cancer – and, most importantly, how we can use this information to improve outcomes for men. Prostate Cancer UK is funding research to do just that.
“Maintaining a healthy weight can protect against many cancers, but it is important to remember that prostate cancer can affect men of all weights, shapes, and sizes. Men over 50, Black men, and men with a family history are at highest risk of the disease and should speak to their doctor if they have concerns.”