Does cycling increase your risk of prostate cancer?

Well, this is just a public health emergency waiting to happen. Image: Getty.

Any plan to give up scarce urban road space to cyclists will inspire many different opponents, peddling many different stories. This one at least wins points for originality. In its first response to the plan for two huge cross-London cycle routes, the Cyclists in the City blog noted:

"The Motorcycle Action Group has already announced its opposition to cycle tracks and – bizarrely – justifies that by saying they will give cyclists higher rates of prostate cancer. (There are too many levels on which that is simply plain weird.)"

The tweet in question has now been deleted (can't think why). Oddly enough, though, this isn't quite as leftfield as it sounds. Over the summer, the (peer-reviewed) Journal of Men's Health published a study which suggests that any policy which significantly increases cycling rates might do just that.

Researchers at University College London surveyed 5,000 male cyclists online, then ranked them by how much they cycled. They then limited the sample to the 2,027 cyclists over the age of 50 (prime prostate territory), before analysing the correlation with the cancer. 

Of the 498 men who biked for more than 8.5 hours a week, 17 (3.5 per cent) had prostate cancer. Of the 511 who biked for less than 3.75 hours, just three (0.5 per cent) did. Once they'd asdjusted the numbers for various other factors, the researchers calculated that the odds of someone who cycles heavily having prostate cancer were six times greater than those of someone who cycles just a little.

Obvious conclusion: stop cycling, wear padded safety pants, never go outside again.

The offending plan: an artist's impression of the north-south cycle route at St. George's Circus, south London. Image: TfL.

Okay, that might be a bit extreme, for a whole swathe of reasons. One is that nine hours is quite a big chunk of the week to spend on a bike: if there is an increased risk, it’s affecting only the hardest of hardcore cyclists. Another is that the group who filled the survey in was self-selecting.

The big one, though, is that all the survey showed is an "association": correlation is not causation, and there's nothing to suggest that time in the saddle has caused the prostate cancer. It is possible, albeit unlikely, that it's the other way round, and somewhere out there there's one bicycle-mad oncologist suggesting it’s the best way of staying active during treatment. 

Another point to note is that 42 is a very small sample, so these results may be down to pure chance. The survey also found no link between cycling and infertility or erectile dysfunction – which is lovely and all (functional genitals, yay!), but also contradicts previous research findings. That rather calls the results into question. 

Even if being a regular cyclist does marginally increase your risk of prostate cancer, it could still be worth doing: cycling, after all, can lead to weight loss and increased fitness, with all the reductions in heart disease, diabetes and so on that that implies. And – let's be realistic – prostate cancer probably less of a threat than being crushed by an HGV. Unlike prostate problems, the lorry risk can't be addressed by changing your saddle.

So, does cycling increase risk of prostate cancer? If you're a woman, then we feel confident in saying that, no, it does not. If you're a man – plausibly, but possibly not, and it's really not worth worrying about.

Now – motorcycling in London. There's a health risk if ever there was one. I’d avoid that if I were you.


What's actually in the UK government’s bailout package for Transport for London?

Wood Green Underground station, north London. Image: Getty.

On 14 May, hours before London’s transport authority ran out of money, the British government agreed to a financial rescue package. Many details of that bailout – its size, the fact it was roughly two-thirds cash and one-third loan, many conditions attached – have been known about for weeks. 

But the information was filtered through spokespeople, because the exact terms of the deal had not been published. This was clearly a source of frustration for London’s mayor Sadiq Khan, who stood to take the political heat for some of the ensuing cuts (to free travel for the old or young, say), but had no way of backing up his contention that the British government made him do it.

That changed Tuesday when Transport for London published this month's board papers, which include a copy of the letter in which transport secretary Grant Shapps sets out the exact terms of the bailout deal. You can read the whole thing here, if you’re so minded, but here are the three big things revealed in the new disclosure.

Firstly, there’s some flexibility in the size of the deal. The bailout was reported to be worth £1.6 billion, significantly less than the £1.9 billion that TfL wanted. In his letter, Shapps spells it out: “To the extent that the actual funding shortfall is greater or lesser than £1.6bn then the amount of Extraordinary Grant and TfL borrowing will increase pro rata, up to a maximum of £1.9bn in aggregate or reduce pro rata accordingly”. 

To put that in English, London’s transport network will not be grinding to a halt because the government didn’t believe TfL about how much money it would need. Up to a point, the money will be available without further negotiations.

The second big takeaway from these board papers is that negotiations will be going on anyway. This bail out is meant to keep TfL rolling until 17 October; but because the agency gets around three-quarters of its revenues from fares, and because the pandemic means fares are likely to be depressed for the foreseeable future, it’s not clear what is meant to happen after that. Social distancing, the board papers note, means that the network will only be able to handle 13 to 20% of normal passenger numbers, even when every service is running.

Shapps’ letter doesn’t answer this question, but it does at least give a sense of when an answer may be forthcoming. It promises “an immediate and broad ranging government-led review of TfL’s future financial position and future financial structure”, which will publish detailed recommendations by the end of August. That will take in fares, operating efficiencies, capital expenditure, “the current fiscal devolution arrangements” – basically, everything. 

The third thing we leaned from that letter is that, to the first approximation, every change to London’s transport policy that is now being rushed through was an explicit condition of this deal. Segregated cycle lanes, pavement extensions and road closures? All in there. So are the suspension of free travel for people under 18, or free peak-hours travel for those over 60. So are increases in the level of the congestion charge.

Many of these changes may be unpopular, but we now know they are not being embraced by London’s mayor entirely on their own merit: They’re being pushed by the Department of Transport as a condition of receiving the bailout. No wonder Khan was miffed that the latter hadn’t been published.

Jonn Elledge was founding editor of CityMetric. He is on Twitter as @jonnelledge and on Facebook as JonnElledgeWrites.