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General information about cancer

What is cancer?

Cancer describes a diverse group of several hundred diseases in which some of the body’s cells become abnormal and begin to multiply out of control as a result of changes (mutations) in the genetic information of the cell. These abnormal cells can form an invasive (i.e. malignant) tumour which can invade and damage the area around them and spread to other parts of the body through the bloodstream or the lymphatic system. If the spread of these tumours is not controlled, they usually result in death. Not all tumours are invasive; some are benign tumours that do not spread to other parts of the body and are rarely life-threatening. 

What is the difference between a malignant and a benign tumour?

Tumours can be benign (not a cancer) or malignant (a cancer). Benign tumours do not invade other tissues or spread to other parts of the body, although they can expand to interfere with other organs. The main features of a malignant tumour (cancer) are its ability to grow in an uncontrolled way and to invade and spread to other parts of the body.

The original site in which a cancerous tumour is formed is referred to as the primary site. The spread of cancerous cells from the primary site to another (i.e. secondary) site is referred to as metastasis.

Why are there different types of cancer?

Cancers are distinguished from each other by the place in the body in which the disease begins. For example, cancer that begins in the lung is called lung cancer and cancer that begins in the breast is breast cancer, regardless of whether or not it has metastasised to other sites.

In addition, cancers are classified by the type of cell involved, which is referred to as the histological type of the cancer. The main categories are:

Carcinoma: Malignancy (i.e. cancer) of the internal or external lining of the body. For example, squamous or epidermoid carcinoma of skin, lip, tongue, cervix.

Sarcoma: Malignancy originating in the connective tissue. For example, bone, cartilage, skeletal muscle, fibrous tissue, neurogenic tissue.

Myeloma: Malignancy of plasma cell series (cells which produce some of the proteins found in the blood). These cells are generally found in the bone marrow.

Lymphoma: Cancer of cells of the lymph nodes or of similar cells which may occur elsewhere.

Leukaemia: Malignancy of the blood-forming elements of the bone marrow. Unlike most other forms of cancer, cancers of the blood, such as leukaemia, do not form a solid tumour but instead invade other areas of the body through the bloodstream.

Mixed types: Cancer composed of different tissue types. The type components may be within one category or from different categories.

Where can I get more information about cancer?

There are a number of different Australian and international organisations that can provide information about cancer including the latest research, risk factors for cancer, cancer treatment and cancer support groups. For more information, see our cancer and screening links.

Cancer data

What legislation deals with cancer data?

The registration of all cancers (except squamous cell carcinoma and basal cell carcinoma of the skin) is required by law, usually under the Public Health Acts, in each state and territory and can be accessed through the state and territory cancer registries.  

What is a cancer registry?

A cancer registry can be defined as an organised system for the collection, storage, analysis and interpretation of data on persons with cancer. Each state and territory in Australia maintains a cancer registry. A subset of data from the state and territory registries is provided to the National Cancer Statistics Clearing House to be compiled into the Australian Cancer Database to enable national patterns and trends in cancer incidence to be monitored.

What is the National Cancer Statistics Clearing House (NCSCH)?

The National Cancer Statistics Clearing House (NCSCH) was established in 1986 as the national repository of cancer incidence and mortality statistics. Its general purpose is to monitor and report on Australia's cancer levels and trends and to help in planning and research that aim to reduce those levels.

The NCSCH is a collaborative partnership of the Australasian Association of Cancer Registries (AACR) and the AIHW and is housed within the Cancer and Screening Unit of the AIHW. The objectives and working structure of the NCSCH are defined in the NCSCH 2010 protocol (315KB PDF).  

What is the Australian Cancer Database (ACD)?

The Australian Cancer Database (ACD) is a national collection of unit record cancer incidence data maintained by the National Cancer Statistics Clearing House at the AIHW. Cancer incidence data are currently available from 1982 onwards to 2007.

What are the most recent data in the Australian Cancer Database (ACD)?

Data in the Australian Cancer Database (ACD) are usually 2-3 years old. This is because data relating to diagnosed cancers for individuals are collated by state and territory cancer registries through information provided by hospitals, pathology laboratories, radiotherapy centres, physicians and Registrars of Births, Deaths and Marriages in their respective jurisdictions. These data are then supplied for national collation through the National Cancer Statistics Clearing House (NCSCH).

How is the Australian Cancer Database (ACD) compiled?

The compilation of state and territory data into the Australian Cancer Database (ACD) is undertaken annually. It involves a variety of checks to identify potential errors. As it is possible for a cancer diagnosis to be recorded by more than one cancer registry duplicate registrations must be found and removed before the production of national statistics can commence.

The ACD is updated and refreshed in its entirety every year. The registration of cancer cases is a dynamic process and older records can be modified if new information is received. In order for these changes to be incorporated into the ACD, a new complete file for all years of cancer data, as well as the most recent year, is supplied by state and territory cancer registries annually. As such, the checks and de-duplication undertaken at the AIHW are applied to the entire ACD every year, rather than just the newest year of data.

Who owns the data in the Australian Cancer Database (ACD)?

The National Cancer Statistics Clearing House (NCSCH) assembles state and territory cancer registry information into a national database. The AIHW acts as custodian of these data for the purposes of producing national cancer statistics. At all times, the state and territory cancer registries retain ownership of their respective jurisdiction's data. The analysis and publication of state and territory data and the facilitation of research at the jurisdictional level remains the prerogative of the state and territory cancer registries.

What cancer incidence data are available?

Data provided to the National Cancer Statistics Clearing House (NCSCH) comprise reports of initial diagnoses, deaths from malignant tumours and deaths of people with cancer due to other causes occurring in Australian residents. The Australian Cancer Database (ACD) contains unit records on all cases of primary invasive cancer diagnosed in Australia from 1982 with the following exceptions and caveats:

  • Basal cell carcinomas (BCC) and squamous cell carcinomas (SCC) of the skin are not included because they are not notifiable diseases.
  • The collection of non-melanoma skin cancers, besides BCC and SCC, is complete from 2001 only.
  • The collection of myelodysplastic syndromes and some myeloproliferative cancers is complete from 2003 only.

Does the Australian Cancer Database (ACD) contain any data on other kinds of neoplasms?

No. The ACD does not hold any data on:

  • non-malignant neoplasms (that is, benign, borderline or in situ neoplasms)
  • recurrences of previously diagnosed cancers
  • secondary (metastatic) cancers.

Does the Australian Cancer Database (ACD) hold data on cancer stage and treatment?

No.

What variables are available for analysis?

The most commonly requested variables are:

  • age at diagnosis
  • sex
  • year of diagnosis
  • type of cancer.

The type of cancer can be specified by a common name (for example, breast cancer), ICD-O-3 topography and histology codes or ICD-10 codes.

Various other data items can be extracted or calculated, but are much less commonly requested (for example, mean age at diagnosis).

Why are there differences in a reported cancer statistic?

There are a few reasons why a cancer statistic may vary, even when reported from the same source. The most common reasons are listed below.

  • The definition of a cancer may vary. For example, the ICD-10 definition of all cancers in the General Record of Incidence of Mortality (GRIM) workbooks comprises ICD-10 codes C00–D48 whereas the corresponding definition in the Australian Cancer Incidence and Mortality (ACIM) workbooks comprises the smaller set of codes C00–C97, D45–D46, D47.1 and D47.3.
  • The presence of inter-state duplicates means that the data from individual cancer registries will differ slightly from data reported by the AIHW. A de-duplication is undertaken by the AIHW to remove records of cancer cases recorded in more than one registry. Information about duplicate registrations is fed back to the respective registries but not will adjust their databases at the same time as each other or as the AIHW.
  • The underlying unit of a cancer statistic may vary. Generally, cancer incidence is reported according to the number of cases. For example, a person diagnosed with both a lung cancer and breast cancer will be counted twice. However, other types of cancer statistics, for example, prevalence, are reported according to the number of people diagnosed with cancer and still alive.
  • Cancer mortality data may be reported by year of death or year of death registration. Generally, AIHW cancer mortality data are reported by the year of death except for the most recent year, where data are reported by the year of death registration. Other sources of mortality statistics (for example, the GRIM workbooks or ABS data) might always report cancer mortality by year of death registration.
  • The Australian Cancer Database (ACD) is refreshed in its entirety every year. The registration of cancer cases is a dynamic process and older records can be modified if new information is received. In order for these changes to be incorporated into the ACD, a new complete file for all years of cancer data, as well as the most recent year, is supplied by state and territory cancer registries annually. As a result, the number of cancer cases reported by the AIHW for any particular year may change slightly over time.
  • There may be changes in the coding and processing of cancer data over time. For example, in the past the agreed approach was to exclude all non-melanoma skin cancer (NMSC) cases from the incidence data produced by the AIHW. However, as of 2009, a new approach was adopted whereby all data that pertain to reportable forms of NMSC were included in the data.

Accessing cancer data

How can I get access to cancer data?

The National Cancer Statistics Clearing House (NCSCH) is able to make available a broad range of statistical data at the national level. The clearing house generates a number of reports using national cancer statistics. Online data for a number of specific cancer sites are also available through the Australian Cancer Incidence and Mortality (ACIM) books. These Excel workbooks provide summary data on the incidence and mortality of all the major cancers as well as all cancers combined.

Users may also request a customised data request of unpublished national data held by the NCSCH. These requests are usually subject to a fee based on cost recovery.

Requests for access to unit record data or data linkage for approved research projects require the approval of the AIHW Ethics Committee and data custodians and ethics committees of all state and territory cancer registries. Securing approval can take from several months to a year and should be factored into project planning.

How do I get cancer data for a particular state or territory?

State and territory cancer registries report in various formats on cancers in their respective jurisdictions. Data for particular jurisdictions are available through the various cancer registry statistics pages.

The National Cancer Statistics Clearing House (NCSCH) generally cannot provide data from individual states and territories, or smaller geographic units, without the approval of the state and territory registries. Requests for national statistical analyses that wish to include breakdowns by state and territory, or other regional categories, are referred to the Australasian Association of Cancer Registries Executive Committee for approval.

Where can I get clinical cancer data?

There is currently no national collection of clinical cancer data; however, a number of specific clinical data collections and data set specifications exist. See our cancer and screening links page for more details.

Screening for cancer

What is cancer screening?

Population-based cancer screening involves the systematic use of a test to identify individuals at risk of cancer. The screening test is not intended to be diagnostic—rather it aims to identify individuals who should be referred for further investigation using diagnostic tests.

The aim of population-based cancer screening is to reduce the burden of this disease, either by detecting cancer at an earlier stage where treatment options are often more effective, or by detecting and treating abnormalities that if left may become cancerous.

Where can I get information about cancer screening?

In Australia, there are organised national population screening programs for breast, cervical and bowel cancers. Monitoring reports for each of the programs are produced annually by the AIHW. Further information on each of the programs is available through the Department of Health and Ageing.