Dodgy data bad for your public health

There are lies, damned lies and statistics. Numerous claimants to coinage. Possibly Benjamin Disraeli.

As a trainstopper the intro to an ABC Health and Wellbeing programme last month [aug] couldn't have been more shocking:

'About one in two Australians will be diagnosed with cancer. That means if you don't get it, the person sitting next to you will.' Later promotions sandwiched 'during their lifetime' between the sentences, though it seemed superfluous.

Will – or may? How could this be? Fifty per cent of the population? That's 12 million people. Surgeries and hospitals would crash.

Cancer is an important issue that demands attention – which it received in the story of a fit young man who cared for his health yet still contracted bowel cancer - but had the ABC got the figures wrong?

Like most Australians I've lost friends and relatives to the disease and know others in treatment. But that's a small minority of my acquaintances.

Denise Musto from Audience and Consumer Affairstook a fortnight to reply that the unit was'satisfied that the story kept with the ABC's editorial standards for accuracy' adding:

'… the statistic was taken from the Cancer Australia website which states: 'In 2016, it is estimated that the risk of an individual being diagnosed with cancer by their 85th birthday will be 1 in 2.' Then it added a rider: '1 in 2 males and 1 in 3 females'.

So the ground had shifted. The birthday clause was not in the original promotion nor was the gender difference. But the data was still frightening.

Cancer Australia'sDr Nerissa Soh said the national government agency got its statistics from on-line books published by the Australian Institute of Health and Welfare.

"In the AllCancers on their Incidence page, there are numbers for the risk of being diagnosed with cancer before the age of 85," she said. "In 2012 this was 1 in 2 and this risk has been the same since 1987."

Is risk certainty? Not in my understanding of language.

Mark Short, Manager of the Australian Cancer Database at the AIHW confirmed his organisation was the source of the figures, but added:

"However, there are some important 'ifs and buts' that go along with it which perhaps the ABC programme did not explain. I'm only going to explain the main one to you because the others would be getting into too much nitty-gritty detail.

"Risk of being diagnosed with cancer by age 85 (1 in 2) does NOT (his emphasis) equate to proportion of people 85 and over who have had a diagnosis of cancer. If that were so, as you point out, half of all people 85+ would have had a diagnosis of cancer (before reaching 85), which is clearly not true.

"What the risk figure is saying is, based on the cancer incidence rate statistics we have right now and assuming that they remain the same into the future, a baby born today has about a 1 in 2 chance of being diagnosed with cancer before they turn 85.

"If that person gets cancer they have a fair chance of dying from it before they turn 85 in which case they disappear from the population (or, just to make matters more complicated, they might never be diagnosed with cancer but still die before turning 85).

"So the people who make it to age 85 are not representative of all the people born 85 years ago; they are the lucky ones, at least as far as longevity goes.

"If you imagine that everyone who dies remains in the population as a zombie (a non-hostile one!), then perhaps about 1 in 2 members of this 'alive + zombie' population will have been diagnosed with cancer before turning 85.

"I say 'perhaps' because, as mentioned in the first paragraph, there are other ifs and buts that go with the mathematical formula that calculates the risk; the risk figure should be taken as approximate rather than exact."

From all this hedging it's clear that the ABC's original statement is at best open to misinterpretation and most certainly depressingly alarmist.

The Australian Bureau of Statistics publishes clearer figures gleaned from the census: 'In 2011-12 there were 326,600 persons who had cancer, or around 1.5 per cent of the Australian population. This reflects little change from 2007-08.'

The real concern that should have drawn the ABC's attention is this: Despite all the advances in preventative measures, sophisticated treatments, social awareness programmes, massive expenditure and intensive world-wide research the risk of getting cancer has remained the same for the past 29 years. Why?

Whatever that risk it certainly doesn't mean that 'if you don't get it, the person sitting next to you will.' Unless that person is an octogenarian statistics juggler. Or a zombie.