A tale of two Sydneys: Social health atlas shows inequity in cancer risk between the rich and poor areas

People living in some of Sydney's most disadvantaged postcodes died of avoidable cancers at significantly higher rates than their more affluent neighbours, according to the Social Health Atlas of Australia published Saturday.

Yet Sydneysiders in wealthier suburbs were more likely diagnosed with a smattering of specific cancers, found the researchers at Torrens University Australia's Public Health Information Development Unit (PHIDU).

Breast cancer was significantly more prevalent in some of the more affluent public health areas (PHAs), with women in the most advantaged postcodes including 26 per cent more likely to be diagnosed than their counterparts in Sydney's more disadvantaged areas, according to the government health data.

NSW chief cancer officer and chief executive of the Cancer Institute NSW Professor David Currow said one of the biggest risk factors for breast cancer – longer uninterrupted oestrogen exposure – was highly associated with affluence.

Over the past century women have started to menstruate at a younger age and go through menopause later in life – largely due to better nutrition – lengthening the period of time their bodies produced oestrogen.

"We know breast cancer is extremely responsive to oestrogen. If your body is growing well and rapidly and you're eating good food you are more likely to get breast cancer," Professor Currow said. 

Starting to have children at an older age, and high alcohol consumption in post-menopausal women – both more prevalent among women in Sydney's most advantaged areas –  were also risk factors at a population level. 

The correlation between cancer and disadvantage was not always significant, but when it came to dying early of cancer, the most disadvantaged were clearly the most at risk. 

Some of the most disadvantaged areas in greater Sydney had the highest rates of premature mortality linked to cancer, while the some of the most affluent suburbs, including Double Bay and Avalon, had some of the lowest premature cancer death rates. 

Mount Druitt had a premature cancer death rate 2.8 times higher than Gordon. 

Yet the inverse was true of cancer hospital admissions.

Patients living in Sydney's most advantaged areas had significantly higher rates of cancer-related hospitalisations than the more disadvantaged suburbs further west. Double Bay had a cancer hospitalisation rate three times that of Cabramatta (3536 versus 1216 per 100,000 people).

And a significantly high rate of people in these areas were being admitted ot private hospitals, director of PHIDU Professor John Glover.

But a range of social determinants were having a marked effect on the health of people in disadvantaged areas, mostly located in the west of Sydney, including income, employment status, housing conditions, education, transport and obesity, as well as access to healthcare, he said.

There was also a strong correlation between high lung cancer rates among men and disadvantage across Sydney, with Pittwater recording the lowest rate of lung cancer, followed by Ku-Ring-Gai, Lane Cove, Manly and North Sydney.

Higher rates of smoking among lower socioeconomic groups was clearly a driving factor not just for lung cancer but all cancer deaths, Professor Glover said. 

"The social determinants that lead to inequality are very strongly implicated in many of the health data," Professor Glover said. 

On the flipside, high melanoma rates largely followed the coastline's affluent postcodes, with their enviable proximity to beaches, and prostate cancer rates generally increased with wealth. 

The more affluent areas, including Mosman, Woollahra and North Sydney had some of the highest prostate cancer rates in Sydney, while suburbs of comparable economic disadvantage (Fairfield, Auburn, Canterbury and Bankstown) had some of the lowest rates.

And the gap between highest and lowest prostate cancer rates was a staggering 38 per cent.

This reverse-health gap was not likely to be a true reflection of prostate cancer prevalence, Professor Glover said. 

Men in more affluent areas had better access to healthcare services and were more readily diagnosed the cancer, whereas men in disadvantaged areas were more likely to die of other causes with the prostate cancer undiagnosed. 

"This explains part of this correlation, if not all of it," Professor Glover said.

Sydney Morning Herald.