More tests after diagnosis

Posted by Sara Liyanage on 30 September 2017

The whirlwind of a breast cancer diagnosis may lead to more tests. Some tests that you may have to undergo, or that you may hear about, are listed below. This is not a complete list. Not everyone will need these tests. Your breast surgeon or oncologist will tell you if you need these tests. Please always ask your medical team about any questions or concerns you have regarding test – the information here is just a starting point for you to then go and find out more from your medical team.

Some of the common tests that you might undergo are the following:

1. Sentinel node biopsy: This is carried out by a needle test or by surgery to test the lymph nodes for cancer cells and thus whether the cancer has spread from your breast to your lymph nodes.

2. Oncotype DX test: Some breast cancers do not require chemotherapy. Your oncologist may carry out this test to see whether you would benefit from chemotherapy.

3. Genetic testing – more testing, more targeted treatment

With thanks to Luca Jahreiss, PhD of Ancora.ai for providing the following explanations of genetic testing for breast cancer:

There is no one-size-fits-all approach to treating breast cancer, so it is key for your doctor(s) to have a detailed diagnosis of your specific cancer to choose the most appropriate treatment. As your cancer may continue to evolve, it will also have to be reevaluated every so often as well.

Genetic testing is a key aspect of a comprehensive breast cancer diagnosis, as there are now a number of breast cancer treatments available that target cancer cells with specific genetic mutations/alterations. Should you be eligible for a targeted treatment, this could mean not having to undergo chemotherapy or at least less of it, thereby experiencing less side-effects.

Genetic tests might only look for a very specific mutation or across a whole panel of genes that have previously been implicated in cancer (there are number of different ones available, e.g. Oncotype Dx, Guardant 360, FoundationOne CDx).  What all those tests have in common is that you will have to provide some DNA (via a saliva or blood sample) and then wait for a few weeks to get the results.  

Here are the most common genetic tests for breast cancer:


  • These genes encode proteins that are involved in DNA repair and therefore help maintain genetic stability. Mutations in these genes increase the likelihood of developing breast cancer earlier, the likelihood of developing a second breast cancer and of a poorer prognosis. Typically, this test is performed in women from families with a history of breast cancer.


  • 70-80% of breast cancers have high levels of receptors for the naturally occurring hormones oestrogen (ER) and progesterone (PR) on their tumour cells. This means that the tumour is dependent on these hormones for growth and can be treated by blocking these receptors or reducing hormone levels. To get to know more about this so-called hormone therapy, see the dedicated blog article


  • 15-20% of breast cancers have a higher number of HER2 receptors on tumour cells, which are involved in cell growth and multiplication. These HER2-positive cancers tend to be more aggressive than HER2-negative ones. There are targeted treatments available that block HER2 receptors in these cancers. To get to know more about the treatment of HER-positive cancers, read about Sara’s personal experience in the dedicated blog article.

Triple-negative (TNBC)

  • 10-15% of breast cancers are triple-negative, i.e. they have neither high levels of hormone receptors nor of HER2 receptors. This means that there aren’t any clear targeted treatments available, meaning that they are usually treated with chemotherapy. Therefore this is one of the cases where broader genetic testing and/or clinical trials as an option (see dedicated section) might be worth considering (see next point below). 

The mutations above are the ones most commonly associated with breast cancer for which a targeted therapy existed. However, there are several other mutations that now have a targeted treatment on the market or in development (for what in development means and how you take advantage of that, please see the section on clinical trials). Therefore, you might also want to consider a broader genetic test across a panel of genes, especially if your cancer is triple-negative or if you don’t or have stopped responding to other treatments. 

Helpful resources and information

The absolute best place to find out more about the sorts of tests that you may undergo after a diagnosis of breast cancer is to get a copy of the book “The Complete Guide to Breast Cancer” by Professor Trisha Greenhalgh and Dr Liz O’Riordan (breast cancer professionals who have also had breast cancer). Their book is full of helpful information about going through breast cancer and understanding the medical side of things.

SNB: Choose the “surgery to the lymph nodes” link from the menu in this link on the Breast Cancer Now website.

BRCA test: The Royal Marsden website has a “Beginner’s Guide to BRCA1 and BRCA2” (visit their site and search for this)

Oncotype DX Test: Information on the Breast Cancer Now website

The information and content provided on this page is intended for informational and educational purposes only and is not intended to substitute for professional medical advice.

Reviewed October 2021


Claire diagnosed in 2016
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