To be absolutely fair, on the statistics front, one in sixty four people (in the UK, according to a quick check) get diagnosed with pancreatic cancer in their lifetime.
157 'cancer hospitals' in China (another quick check, after failing to find the number of 'cancer labs'), assume each has (only!) 37 students under a single given researcher and they all spend just three years of their life there (though obviously that should ideally be age-adjusted as well)... Running the maths, on such very loosely estimated figures as I am assuming, the pure chances that several sites have (at least) one such exact diagnosis is fairly good. All it takes is a chance clustering and *alarm bells!!!* (And I bet/hope there are far more than 5809 such students in china, however so distributed.)
Not to say that the target individual isn't a bad man (or bad at his job), but it could well be a matter of looking for anything 'suspicious'. (If it isn't pancreatic cancer, it's prostrate - 1 in 8 of half the number of students is significantly into the double-digit sites having at least one student succumb. Choose your illness, or indeed choose from any illness and pick on the outliers that will inevitably be there to be discovered because of pure, unfortunate, bad luck. And there's a whole plethora of legal pitfalls anyone could be nudged into, including 'corruption' from minor financial irregularities - inadvertent, accidental, perceived or similarly contrived...)
The cynic in me thinks that this is an unduly inflated problem which just needs more rational thinking about. The pessimist in me thinks that it's deliberately inflated (by p-hacking) to find a cause to prosecute that is totally unrelated to the real intent to pick on this individual. (Or any individual, whoever would be the unlucky one to be made 'an example of'. That means you don't need the 'problem' to occur to anyone in particular, just anybody at all....)
But nothing I say will help (or hinder) the cause of justice. Or, most importantly, those suffering from the cancers.
(Also, the Fukushima 'scare' in China is notably overblown. The water released (with tritium, which is already being released by Chinese nuclear power stations (and everybody else's) as standard) is far lower in radioactivity than the worldwide agreed Drinking Water standards. Into a Pacific current that will further dilute it (as it also decays with a half-life of 12 years) long before it compromises Chinese 'waters'. And probably causes much less problems than regular industry/thermal power-stations in the region. But it's a stick to beat their neighbour with/rile up their own population, another thing I can't imagine my being able to help by explaining these things.)