Tumour testing

Genes contain information for the cells of the body to function in the form of a “code” that the cell “reads”. Each gene has a specific function. Some genes are involved in making sure the cell grows and divides normally. Research has shown that cancers are caused by gene changes (“errors in the code”), causing abnormal cell growth within the cancer cells. Less commonly, these gene changes are found to be inherited and cause individuals to be predisposed to developing cancer. In some cases, drug treatments exist which are aimed at specific gene changes. Complex genomic profiling can be used to identify variations in your cancer to determine whether there are drug treatments that would target your cancer.

Research has shown that this type of testing can change the diagnosis and management of patients with advanced cancer.

A tumour test can determine if a cancer is linked to either:

• a hereditary gene mutation (germline) or
• a non-hereditary gene mutation (somatic), that may occur randomly inside the tumour.

A tumour test may impact a person’s treatment options such as being able to access more personalised treatment. You can ask your doctor or oncologist about taking a tumour test.

Why is tumour testing important?

Tumour testing can provide information that informs the choices of treatment that can be used at the time of diagnosis and if the cancer comes back.

If you have been newly diagnosed with cancer, it is important to know whether you have a hereditary or non-hereditary gene mutation inside your tumour. This information will identify whether you may be eligible for treatment with certain precision medicines or targeted treatments for your specific tumour type.

If you have a hereditary gene mutation in your BRCA1 or BRCA2 genes, or other genes such as RAD51C, RAD51D, BRIP1, PALB2, MLH1, MSH2, MSH6, PMS2, your blood (biological) relatives may also have them. A blood test will confirm if they have the same gene mutation. This is important because people who have gene mutations need to manage and reduce their risk of cancer.

What does a tumour test involve?

There are currently two methods of testing for gene mutations that cause cancer:

1. Germline testing – Undertaken on blood samples to detect inherited disease-causing gene mutations. Results can have implications for family members and a cancer patient.
2. Tumour testing – Involves extracting DNA from a small piece of the tumour and testing it for disease-causing gene mutation or somatic mutations. A newer test called ctDNA or liquid biopsy is sometimes used and involves a blood test rather than testing the actual tumour in the person.

Approximately two-thirds of mutations detected in tumours are inherited and nearly one-third are non-inherited mutations.

When is the best time to get a tumour test?

If you have been diagnosed with cancer and your specialist team has recommended treatment with chemotherapy before surgery (neoadjuvant chemotherapy), it is preferable to have a ‘core biopsy’ taken for tumour genetic testing before your treatment starts. This will not delay you starting chemotherapy.

A core biopsy involves a small piece of tumour being removed from your body under local anaesthetic while a CT scan is simultaneously performed to guide the biopsy needle.

If surgery is at the start of your treatment (primary surgery) before chemotherapy, tumour tissue can be collected during your surgery and sent for tumour testing after surgery.

Who do I ask for a tumour test?

Tumour tests are not recommended for all types of cancer. Ask your oncologist whether you are eligible to have a tumour test to confirm your tumour type and determine your treatment options.

Download our Tumour Test Checklist for a list of helpful questions to ask your doctor.

What is the difference between hereditary and non-hereditary biomarkers?

Biomarkers are an indicator of a particular biological condition. Sometimes biomarkers are hereditary.

An example of a hereditary biomarker is the BRCA1 gene or BRCA2 gene mutations.

An example of a non-hereditary biomarker is ‘somatic’ gene mutations, which are mutations and disease-causing gene variants that arise spontaneously in a tumour as it grows. These are not inherited from a parent and cannot be passed on to a child. These mutations occur only in the tumour and not elsewhere in the body.

Somatic (‘tumour only’) mutations can also occur in the BRCA1 gene and BRCA2 gene.