Whole Genomic Sequencing (WGS) - Frequent questions answered. - Brainstrust, brain tumour charity

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Posted 10th October 2024

In Brain News, Research News

What is Whole Genomic Sequencing?

Whole-genome sequencing (WGS) is the analysis of the entire genomic DNA sequence of a cell at a single time, providing the most comprehensive characterisation of the genome.

Why is it important?

WGS has revolutionised bioscience and has proven to be essential and invaluable to the identification of gene functions and their involvement in disease. It explores a much larger sequence in comparison to targeted approaches and therefore generates much more information about communities.

Here we have some frequently asked questions that we hear about WGS. The FAQs signpost further reading for you about Whole Genomic Sequencing ‘WGS – a very hot topic’. You can read this here.

You can read the Darzi report on the state of the NHS, including cancer care, here.

And the Tessa Jowell Brain Cancer Mission’s report into genomic testing and brain tumours here

Whole Genome Sequencing FAQs for brain tumour patients and their caregivers

Introduction

The Brain Tumour Data Dashboard lets you explore up -to-date, population level data about the brain tumours diagnosed in England between 2013 and 2015. Using the drop down menus on the left you can select different groups of patients to view in the charts below. In these charts the number of patients for every 100 diagnoses is displayed as images of people. Patients have been grouped by date of diagnosis, type of tumour, age, gender, and region in England.

For each group of patients you can explore the different routes to diagnosis, the proportion of those who received chemotherapy or radiotherapy, as well as the survival of the patients within each group. For more information about what these metrics mean please see the glossary.

How to use

Select the year of diagnosis using the drop down menu.
Select your patient group of interest from the four drop down menus in the following order:
1. Tumour group
2. Age at diagnosis
3. Region of England
4. Gender of patient
To view a second chart to compare different groups of patients, click the ‘compare’ button.The second chart will appear below the first chart.

*Note that the tool is best used on a laptop or tablet rather than a mobile phone*

Unavailable data

Some of the data in these charts is not available.There are two main reasons for this:

How the data has been grouped

If you cannot select a patient group from the drop down menus, the data is unavailable because of how the data has been organised.

Public Health England has grouped the data like a branching tree. The bottom of the tree contains all the patients with brain tumours, and then each branch divides the data by a certain characteristics, like age, or location of tumour. But the data is divided in an order, starting with location of the tumour (endocrine or brain), then by age, region, and gender. Age is at the start because it makes a bigger difference to survival rates and treatment rates than gender or region. Sometimes, after the data has been split by type of tumour and age, there is not enough data to be split again. This is because to protect patient confidentiality groups cannot contain less than 100 patients. Because some groups cannot be split further, you cannot create ‘totals’ for everyone by region or gender. For example, you cannot see results for all ages by region, or all brain tumours by gender. If these totals were calculated and released, it might be possible to identify patients, which is why Public Health England cannot release this data.

Statistical reasons and data availability

If you can select a patient group from the chart menus, but the chart does not display, the data is unavailable for one of several reasons:

Data is not yet available for the selected year from Public Health England.
Data is not available because the data quality is too poor to release this statistic.
Data is not available as the statistic is not appropriate for this group.
Data is not available because the standard error of the estimate was greater than 20% and so the estimate has been supressed.

Incidence

The number or rate (per head of population) of new cases of a disease diagnosed in a given population during a specified time period (usually a calendar year). The crude rate is the total number of cases divided by the mid-year population, usually expressed per 100,000 population.

Malignant

Malignant tumours which grow by invasion into surrounding tissues and have the ability to metastasise to distant sites

Mortality

The number or rate (per head of population) of deaths in a given population during a specified time period (usually a calendar year). The crude rate is the total number of deaths divided by the mid-year population, usually expressed per 100,000 population.

Non-malignant

Not cancerous. Non-malignant tumours may grow larger but do not spread to other parts of the body.

Survival

The length of time from the date of diagnosis for a disease, such as cancer, that patients diagnosed with the disease are still alive. In a clinical trial, measuring the survival is one way to see how well a new treatment works. Also called ‘overall survival’ or ‘OS’.

Routes to Diagnosis

Under the ‘Routes to Diagnosis’ tab in the Brain Tumour Data Dashboard, you can explore the ways patients have been diagnosed with brain tumours. There are many ways, or routes, for cancers to be diagnosed in the NHS. A ‘route to diagnosis’ is the series of events between a patient and the healthcare system that leads to a diagnosis of cancer. The routes include:

Two Week Wait

Patients are urgently referred by their GP for suspected cancer via the Two Week Wait system and are seen by a specialist within 2 weeks where they are diagnosed.

GP referral

Diagnosis via a GP referral includes routine and urgent referrals where the patient was not referred under the Two Week Wait system.

Emergency Presentation

Cancers can be diagnosed via emergency situations such as via A&E, emergency GP referral, emergency transfer or emergency admission.

Outpatient

Outpatient cancer diagnoses include diagnoses via an elective route which started with an outpatient appointment that is either a self-referral or consultant to consultant referral. (It does not include those under the Two Week Wait referral system).

Inpatient elective

Diagnosis via an inpatient elective route is where diagnosis occurs after the patient has been admitted into secondary care from a waiting list, or where the admission is booked or planned.

Death Certificate Only

Diagnoses made by Death Certificate Only are made where there is no more information about the cancer diagnosis other than the cancer related death notifications. The date of diagnosis is the same as that of the date of death.

Unknown

For some patients with a cancer diagnosis, there is no relevant data available to understand the route to diagnosis.

More information

If any of the statistical terms in this section of the brainstrust website are hard to understand, we recommend looking them up here:

Cancer Research UK’s Cancer Statistics Explained

http://www.cancerresearchuk.org/health-professional/cancer-statistics/cancer-stats-explained/statistics-terminology-explained#heading-Seven

If you are looking for help understanding terms relating specifically to brain tumours, and treatment, then the brainstrust glossary is available here:

https://www.brainstrust.org.uk/advice-glossary.php