Cancer

age‑standardisation: A method of removing the influence of age when comparing populations with different age‑structures. This is usually necessary because the rates of many diseases vary strongly (usually increasing) with age. The age structures of the different populations are converted to the same ‘standard’ structure and then the disease rates that would have occurred with that structure are calculated and compared.

age‑standardised rate: A rate that results from removing the influence of age by converting the age‑structures of the different populations to the same ‘standard’ structure. This provides a more valid way of comparing rates from populations with different age‑structures.

age-specific rate: the rate for a specific age-group. The numerator and denominator relate to the same age group.

asymptomatic: No apparent signs (symptoms) of disease.

benign: Term that describes non-cancerous tumours that may grow larger but do not spread to other parts of the body.

biopsy: The removal of tissue for microscopic examination by a pathologist. There are different types of biopsy, based on the method used to remove tissue: incisional biopsy removes a small sample of tissue, excisional biopsy removes an entire section of tissue and needle biopsy removes a sample of tissue or fluid with a needle.

cancer (malignant neoplasm): A large range of diseases in which some of the body’s cells become defective, begin to multiply out of control, can invade and damage the area around them, and can also spread to other parts of the body to cause further damage.

carcinoma: A cancer that begins in the lining layer (epithelial cells) of organs such as the lungs.

chemotherapy: The use of drugs (chemicals) to prevent or treat disease, with the term being applied for treatment of cancer rather than for other uses.

cohort method: a method for calculating survival. It follows a group (cohort) of patients all diagnosed in a specified era, e.g. 2005–2009, and calculates the proportion of the original cohort that is still alive after a specified period of time after diagnosis, e.g. 5 years. Compare to the period method.

colonoscopy: A procedure to examine the bowel using a special scope (colonoscope) usually carried out in a hospital or day clinic.

conditional survival (conditional relative survival): The probability of an individual being alive for a given amount of time (such as one or five years), provided that they have already survived a specific amount of time after diagnosis.

crude rate: the number of events in a given period divided by the size of the population at risk in a specified time period.

diagnosis: The process of identifying cancer based on its signs and symptoms. A definitive diagnosis of cancer can only be made by a pathologist (see pathology).

detection: The process of identifying an abnormality of tissue or cells that may be cancerous.

ductal carcinoma in situ (DCIS): A non-invasive tumour of the mammary gland (breast) arising from cells lining the ducts.

DNA repair genes: DNA repair genes, such as the mismatch repair (MMR) gene family, function normally to correct errors in cellular replication. When mutated these genes are unable to correct mutations in tumour suppressor genes or proto-oncogenes that may in turn lead to tumour formation. Mutations in the MMR genes (MSH2, MLH1 and MSH6) are known to cause familial (inherited) colorectal, breast and ovarian cancers.

genetic testing: The process of testing for the presence of particular genetic mutations. This form of testing is available to individuals at increased risk for inherited (familial) cancers, based on a strong family history of those cancers. The breast (and ovarian) cancer genes BRCA1 and BRCA2 are examples of genes with well-characterised mutations that can be ‘screened’ for in high-risk individuals. The presence of those mutated genes indicates an increased risk of developing breast or ovarian cancers. Similar to other screening tests, individuals receiving a positive test result may be referred for further investigation, or choose to undergo regular tests for pre-cancerous cells.

iFOBT (immunochemical faecal occult blood test): A test used to detect tiny traces of blood in a person’s faeces that may be a sign of bowel cancer. The iFOBT is a central part of Australia’s National Bowel Cancer Screening Program.

grade: The microscopic description and classification of tumour cell abnormality – that is, how different the tumour cells appear from normal, healthy cells – and an indicator of how quickly a tumour might grow and spread. This information can be used in determining treatment plans.

histology: The microscopic characteristics of cellular structure and composition of tissue.

incidence: Incidence indicates the number of new cancers diagnosed during a specified time period (usually one year).

invasive: See malignant.

in situ: A tumour that has not invaded surrounding tissue but in some people or conditions could undergo further change and become invasive. Some authorities call this non-invasive cancer while others say that it is not cancer.

lymphoma: Cancer that involves lymphatic system cells (lymph nodes, spleen).

leukaemia: Cancer that begins in the blood-forming tissue, such as the bone marrow, and causes large numbers of abnormal blood cells to be produced and enter the blood. Leukaemia does not usually form a solid tumour.

malignant: A tumour with the capacity to spread to surrounding tissue or to other sites in the body. See also Invasive.

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

mammogram: A radiographic depiction of the breast.

metastasis: See secondary cancer.

mortality: Mortality refers to the number of deaths that occur at a specific time (usually one year) for which the underlying cause of death is cancer.

mutation: A harmful change in ‘normal’ DNA (the molecular building blocks of all cells). Some mutations are inherited and can be passed from parent to child. Others are acquired during a lifetime, the result of other factors such as age, tobacco use, infection with viruses, or exposure to ultraviolet radiation (sunlight). Mutations in genes that regulate cell division may lead to cancer. There are four main gene types that increase the risk of cancer when mutated: tumour suppressor genes, proto-oncogenes, DNA repair genes and programmed death genes. These are described further below.

myeloma: Cancer that involves the plasma cells (found in bone marrow).

neoplasm: An abnormal (‘neo’ = new) growth of tissue. Can be benign (not a cancer) or malignant (a cancer) (see also invasive). Also known as a tumour.

oncology: A branch of medicine that specialises in the diagnosis and treatment of cancer. Sub-specialties include: medical oncology (the use of medication to treat cancer), radiation oncology (the use of radiation therapy to treat cancer), and surgical oncology (the use of surgery to treat cancer).

pathology: The study of disease process. A specialist in this field is called a pathologist. Sub-specialised diagnostic activities with relevance for cancer are histopathology/histology (microscopic examination and description of tissue) and haematopathology (the microscopic examination and description of blood and lymph).

pap smear (pap test): Papanicolaou smear, a procedure to detect cancer and pre-cancerous conditions of the female genital tract.

period method: a method for calculating survival. It specifies a period of time, e.g. 2010–2014, and calculates survival based on all patients who live part or all of their post-diagnosis life during that period. Compare to the cohort method.

prevalence: The total number of people alive at a specific date who have ever been diagnosed with cancer during a time period (such as previous five years).

primary cancer: A tumour that is at the site where it first formed (see also Secondary cancer).

population-based cancer screening: Involves the systematic use of a test or series of tests to identify individuals at risk of cancer. The screening test is not intended to be diagnostic – 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 disease, either by detecting cancer at an earlier stage when treatment options are often more effective, or by detecting and treating abnormalities that if left may become cancerous.

proto-oncogenes: Proto-oncogenes, such as the viral oncogene BRAF, have varying functions to stimulate cell growth and when mutated become cancer-inducing oncogenes that promote ongoing uncontrolled cellular replication and tumour formation. Mutations in the BRAF gene are found in approximately 50% of malignant melanomas.

programmed death genes: Programmed death genes, such as the B-cell lymphoma 2 (BCL2) gene, function normally to regulate cell death and maintain tissue integrity. When mutated these genes either prevent or are unable to induce cell death, leading to the replication of faulty cells and tumour formation. Mutations in the BCL2 gene are found in non-Hodgkin lymphomas and chronic lymphocytic leukaemias.

radiotherapy: The use of high-energy radiation from x-rays, gamma rays, neutrons, protons, and other sources to kill cancer cells and shrink tumours. The radiation source may be applied externally, or internally.

relative survival: The probability of an individual being alive for a given amount of time after diagnosis (such as one or five years) compared with the corresponding general population.

recurrence: Cancer that has returned (recurred) after a period of remission. The cancer may recur at the primary site, or elsewhere in the body, as a secondary tumour.

Registry Derived (RD) cancer stage: refers to the extent or spread of cancer at the time of diagnosis – the higher the number (between I and IV), the further the cancer has spread.

remission: A decrease in or disappearance of the signs and symptoms of cancer. Remission may be partial (a reduction in some or many symptoms) or complete (all symptoms have disappeared). Remission is not the same as a cure. Even in complete remission cancer cells may still be in the body.

sarcoma: Cancer that begins in bone, cartilage, fat, muscle, blood vessels, or other connective or supportive tissue.

screening: Testing or examination of asymptomatic individuals for a specific cancer. The screening process may be indiscriminate, opportunistic (during a routine health check) or systematic (see, population-based cancer screening).

secondary site cancer: A tumour that originated from a cancer elsewhere in the body. Also referred to as a metastasis.

stage: The extent of a cancer in the body. Staging is usually based on the size of the tumour, whether lymph nodes contain cancer, and whether the cancer has spread from the original site to other parts of the body.

surgery: A form of treatment that involves an operation, and may involve the removal of tissue, change in the organisation of the anatomy or placement of prostheses.

survival: see relative survival and conditional survival (conditional relative survival).

symptom: Any indication of a disorder that is apparent to the person affected.

targeted (molecular-based) treatments: Improved understanding of the molecular characteristics of tumours, and the genetic causes, have led to targeted, precision or personalised treatments for some cancers. An example is the use of Herceptin to treat HER-2 type breast cancers (those that have a mutation of the HER-2 gene).

tumour: An abnormal growth of tissue. Can be benign (not a cancer) or malignant (a cancer).

tumour suppressor genes: Tumour suppressor genes, such as the tumour protein p53 (TP53) gene, function normally to regulate cell replication and when mutated are unable to prevent uncontrolled replication and tumour formation. Mutations in the TP53 gene are found in more than 50% of tumours.

virulence: The ability of cancer to cause damage to its host. A virulent cancer is fast-growing and invasive. These cancers are also referred to as ‘aggressive’. A non-virulent or less-virulent cancer is slower-growing and less likely to be invasive or metastasise. A slow-growing cancer may be referred to as ‘indolent’.