Cancer of unknown primary site in Australia

Cancer of unknown primary site was the 11th most commonly diagnosed cancer in Australia in 2013. It is estimated that it will become the 14th most commonly diagnosed cancer in 2017.

New cases of cancer of unknown primary site  

In 2013, there were 2,704 new cases of cancer of unknown primary site diagnosed in Australia (1,416 males and 1,288 females). In 2017, it is estimated that 2,555 new cases of cancer of unknown primary site will be diagnosed in Australia (1,346 males and 1,209 females).

In 2013, the age-standardised incidence rate was 10 cases per 100,000 persons (12 for males and 8.6 for females). In 2017, it is estimated that the age-standardised incidence rate will be 8.5 cases per 100,000 persons (10 for males and 7.3 for females). From age group 40–44, the incidence rate of cancer of unknown primary site is expected to generally increase with age.

In 2017, it is estimated that the risk of an individual being diagnosed with cancer of unknown primary site by their 85th birthday will be 1 in 94 (1 in 78 males and 1 in 114 females).

The number of new cases of cancer of unknown primary site diagnosed increased from 2,140 (1,117 males and 1,023 females) in 1982 to 2,704 in 2013. Over the same period, the age-standardised incidence rate decreased from 18 cases per 100,000 persons (21 for males and 15 for females) in 1982 to 10 cases per 100,000 persons in 2013.

Deaths from cancer of unknown primary site

In 2014, cancer of unknown primary site was the 6th leading cause of cancer death in Australia. It is estimated that it will remain the 6th most common cause of death from cancer in 2017.

In 2014, there were 2,495 deaths from cancer of unknown primary site in Australia (1,284 males and 1,211 females). In 2017, it is estimated that this will increase to 2,830 deaths (1,369 males and 1,461 females).

In 2014, the age-standardised mortality rate was 9.0 deaths per 100,000 persons (10 for males and 7.8 for females). In 2017, it is estimated that the age-standardised mortality rate will be 9.3 deaths per 100,000 persons (10 for males and 8.7 for females). From age group 40–44, the mortality rate of cancer of unknown primary site is expected to generally increase with age.

In 2017, it is estimated that the risk of an individual dying from cancer of unknown primary site by their 85th birthday will be 1 in 80 (1 in 75 males and 1 in 84 females).

The number of deaths from cancer of unknown primary site increased from 574 (291 males and 283 females) in 1968 to 2,495 in 2014. Over the same period, the age-standardised mortality rate increased from 6.8 deaths per 100,000 persons (7.7 for males and 6.1 for females) in 1982 to 9.0 deaths per 100,000 persons in 2014.

Estimated age-specific incidence and mortality rates for cancer of unknown primary site, by sex, 2017

This line chart presents the estimated age-specific incidence (solid line) and mortality (dashed line) rates of cancer name for males (blue), females (purple) and persons (green) in 2017. The age-specific incidence and mortality rates are shown on the primary (left) y-axis, with 5-year age groups from ages 0–4 to 85+ shown on the x-axis.

Source: AIHW [11].

Age-standardised incidence rates for cancer of unknown primary site 1982–2013 and age-standardised mortality rates for cancer of unknown primary site 1968–2014, by sex

This line chart presents the estimated age-standardised incidence (solid line) and mortality (dashed line) rates (per 100,000) of cancer name for males (blue), females (purple) and persons (green) over the period 1982–2013 for incidence and 1968–2014 for mortality. The age standardised incidence and mortality rates, expressed per 100,000 persons, are shown on the primary (left) y-axis. Years from 1968 to 2014 are presented on the x-axis.

Source: AIHW [11].

Survival from cancer of unknown primary site 

In 2009–2013, individuals diagnosed with cancer of unknown primary site had a 13% chance of surviving for 5 years compared to their counterparts in the general Australian population.
 

Between 1984–1988 and 2009–2013, 5-year relative survival from cancer of unknown primary site improved from 6.2% to 13%.

5-year relative survival from cancer of unknown primary site, by sex, 1984–1988 to 2009–2013

This line chart presents 5-year relative survival at diagnosis for cancer of unknown primary site by males, females and persons over the period 1984–1988 to 2009–2013. The percentage of survival is presented on the y-axis.

Source: AIHW [11].

Survivorship population for cancer of unkown primary site 

The survivorship population is measured using prevalence data. Prevalence refers to the number of people alive who have previously been diagnosed with cancer of unknown primary site.

The prevalence for 1, 5 and 31 years given below are the number of people living with cancer of unknown primary site at the end of 2012 who had been diagnosed in the preceding 1, 5 and 31 years respectively.

At the end of 2012, there were 1,084 people living who had been diagnosed with cancer of unknown primary site that year, 2,917 people who had been diagnosed with cancer of unknown primary site in the previous 5 years (from 2008 to 2012) and 6,745 people who had been diagnosed with cancer of unknown primary site in the previous 31 years (from 1982 to 2012).

References

11. Australian Institute of Health and Welfare 2017. Australian Cancer Incidence and Mortality (ACIM) books.