Looking ahead: cancer projections for 2020

Cancer has touched the lives of most Australians in some way. Its impact is felt among individuals, families and the health-care system—and the number of Australians affected is forecast to rise.

Cancer is estimated to be the leading cause of burden of disease in the nation, and the number of new cases is predicted to rise by 40% between 2007 and 2020. This means the number of Australians diagnosed with cancer each year is expected to reach 150,000 by 2020.

'But the news isn't as bad as it sounds,' the Head of the Institute's Cancer and Screening Unit, Christine Sturrock, says.

'The increase in cancer cases is largely a result of an increasing population. So, for many types of cancer, while it looks like the number of cancer cases is climbing, the rate, that is, the number of cases diagnosed per 100,000 people, will actually stay the same.'

The increase in cancer incidence is also linked to Australia's ageing population.

'Cancer is more prevalent in older age groups, so the ageing of Australia's population will also have an impact on cancer rates and prevalence,' Ms Sturrock said.

Cancer projections are important for health service planning and resource allocation in the future.

'Investment decisions in cancer treatment facilities, workforce planning and evaluation of cancer policy rely not only on knowing how many cases of cancer were diagnosed in a given year, but on how many can be expected to be diagnosed in the future,' she said.

The latest report, Cancer incidence projections, Australia 2011 to 2020, presents detailed projections of the number of new cases expected to occur each year to 2020. These projections are based on past trends in national cancer incidence data between 1982 and 2007.

The projections are presented for males and females at the national level for all cancers combined, as well as the most commonly diagnosed cancers.

Cancer rates likely to fall for men

For men and boys, the total number of cases is predicted to rise; however, the cancer incidence rate (new cases per 100,000 people each year) is actually predicted to fall.

'Among males, cancer incidence is highly influenced by prostate cancer, which accounts for about 30% of all cases and is the second most common cause of cancer-related death in males after lung cancer,' Ms Sturrock said.

Incidence rates of prostate cancer in Australia have fluctuated since 1982. Early detection and changes in diagnostic procedures have contributed to the sharp increases in the incidence rate in recent decades.

'However, if we assume that prostate cancer incidence will stabilise in the future, then this is expected to lead to an overall fall in cancer incidence rates in males from 595 to 568 cases per 100,000 between 2007 and 2020,' Ms Sturrock said.

Prostate cancer is expected to remain the most common cancer diagnosed among males in 2020, followed by bowel cancer and melanoma of the skin.

Rates of lung, stomach and pancreatic cancer for males are also projected to fall.

'Unfortunately the news isn't so good for other cancers among men,' Ms Sturrock said.

'Rates are expected to rise for cases of melanoma as well as liver, thyroid and testicular cancer.'

Rising rates predicted for women

Among women and girls, the overall cancer incidence rate is projected to rise from about 394 to 408 cases per 100,000 between 2007 and 2020.

'For women, increases are expected in rates of melanoma, lung, liver and thyroid cancer, while rates of stomach cancer are expected to fall,' Ms Sturrock said.

Breast cancer is the most commonly diagnosed cancer in females and is projected to continue to be the most common cancer diagnosed in females in 2020, followed by bowel cancer, melanoma and lung cancer.

'Over time, there have been a number of changes in the incidence trends of breast cancer among women,' Ms Sturrock said.

'For example, there was a sharp increase in the rate of breast cancer diagnosed between 1990 and 1995, which was most likely due to the introduction of mammographic screening programs between 1989 and 1994.

'Between 1995 and 2002, incidence rates slowed and in recent years we have noticed a very slight decrease in rates.

'Unfortunately, it isn't possible to tell if this decrease will continue, and we estimate that age-standardised rates of breast cancer will remain constant at about 113–114 cases diagnosed per 100,000 females each year between 2011 and 2020.'.

Screening expected to slow rates of bowel cancer

In Australia, bowel cancer is the second most commonly diagnosed cancer in males.

Bowel cancer also accounts for 10% of all deaths from invasive cancers, making it the second most common cause of cancer-related death after lung cancer.

Based on trends to 2007, incidence rates are projected to fall in men, and remain stable in women. However, the introduction of the National Bowel Cancer Screening Program from 2006 is expected to reduce the incidence of bowel cancer in the long term as pre-cancerous conditions are detected and treated.

Rising rates of melanoma

Exposure to ultraviolet radiation, from both the sun and solariums, is the major cause of melanoma in Australia.

Skin cancer prevention programs have operated in all Australian states and territories since the early 1980s, resulting in a significant slowing in the upward trend of melanoma. But melanoma of the skin is still the third most commonly diagnosed cancer in males.

The incidence of melanoma rose by 151% in males and 46% in females between 1982 and 2007. To what extent this rise is due to an increase in the underlying disease, or due to improved detection methods, is unknown.

'We expect that melanoma in men will continue to increase to about 74 cases diagnosed per 100,000 males in 2020, with the largest increase expected to occur in men aged 65 and over,' Ms Sturrock said.

'Melanoma in women is also expected to increase, with around 45 new cases diagnosed per 100,000 females in 2020.'

Lung cancer drops with decreased smoking

Lung cancer is the fifth most commonly diagnosed invasive cancer in Australia, and causes more deaths than any other cancer in both males and females because of its high incidence rate and low survival rate.

Tobacco smoking is the largest single risk factor for lung cancer in Australia, and is responsible for about 90% of lung cancers in males and 65% in females. Trends in smoking have changed over time and vary for males and females. Rates of smoking in males have dropped from an estimated 58% in 1964 to 18% in 2007. For females, the overall smoking rate peaked in the mid-1970s at about 33%, but more than halved to 15% in 2007.

'The incidence rate of lung cancer among men decreased significantly between 1982 and 2007,' Ms Sturrock said.

'Following this trend, we expect that lung cancer in males will continue to fall from about 58 cases diagnosed per 100,000 males in 2007 to about 49 cases per 100,000 males in 2020.'

Unlike the decreasing trends for men, trends in the rate of lung cancer for women have been increasing since 1982, consistent with the later peak in the smoking rate of women. Increases have slowed since 1990 but lung cancer in females will continue to rise slowly from about 31 per 100,000 females in 2007 to about 36 cases per 100,000 females in 2020.

If the number of Australians who smoke continues to fall, which is expected, the incidence of lung cancer will be further reduced in the future.