How personalised treatment makes such a difference for breast cancer survival

August 16th, 2017

The term ‘personalised treatment’ is based on the idea that by understanding the genetic makeup of a person’s disease, treatments can be more accurately tailored to them. This approach is also referred to as ‘precision medicine’.

Not all breast cancer tumours are the same, in fact, there are quite a few subtypes of breast cancer and they are broadly broken into four groups based on their molecular signature (or lack thereof).

Cancer is fundamentally a disease of abnormalities in the genetic material that make up cells and these abnormalities are likely to be different in each person. Each tumour cell has certain hormones and protein receptors which, depending on many are present, play an important role in the growth of the tumour.

Modern targeted therapies are designed to block or switch off these receptors or proteins, thereby halting tumour growth. As every tumour is different, each patient may respond differently to a given treatment.

As a result of breakthrough discoveries, we have seen the treatments for breast cancer evolve from a one-size-fits-all approach to a highly sophisticated personalised approach that aims to target the characteristics of each tumour and get the best outcome for each individual.

A new way to classify cancer

Cancers used to be largely classified by their area of origin within the body, such as the breast, lungs and blood. As we learn more about the genetic makeup of cancers this new information can be used to categorise cancers more specifically, according to how they grow, survive and spread.

In the case of breast cancer, we now know that there isn’t just one type of cancer that originates in the breast – there are many subtypes that are defined by their genetic makeup.

Because cancers are now classified according to their genetic characteristics, the same genetic characteristics may be identified in cancers from other parts of the body. This opens the door for researchers to determine if this personalised treatment approach could work across cancers of different origin.

Personalised treatment at its best

One of the most aggressive forms of breast cancer is HER2-positive cancer (human epidermal growth factor receptor 2). This subtype accounts for about 20 per cent of breast cancers and, until a few decades ago, these women typically had a poorer outlook.

A major breakthrough came when researchers discovered that these tumours have extra copies of the HER2 receptor gene that promote cancer cell growth.

A drug called Herceptin was developed to specifically target the HER2 protein and has had a dramatic success in improving survival for these women, so much so that it has become standard treatment – a personalised treatment based on the genetic makeup of the tumour.

It has recently been discovered that excessive HER2 is also present in about 8 per cent of gastric cancers and 3 per cent of pancreatic cancers.1 This means a therapy successful in one location has the potential to work in another, because the tumour types are similar.

Clinical trials are currently assessing whether HER2-targeted drugs can then also be effective against these pancreatic tumour types.

Not all breast cancers have targeted treatments

There are still around 10 per cent of breast cancers for which no targeted treatment yet exists. These are broadly referred to as triple negative breast cancers and are a group with varied genetic characteristics. As yet, no reliable receptors or proteins have been identified in these cancer cells so effective treatments are not able to be developed.

These tumours are typically more aggressive and have a higher presence among younger women diagnosed with breast cancer.

Many researchers have identified this subtype as a critical area of focus to reduce the number of deaths from breast cancer each year. If every woman with breast cancer, regardless of the subtype, had a specific and personalised treatment plan, survival would improve dramatically.

Research has the answers

The National Breast Cancer Foundation funds research into making treatments for breast cancer more effective.

Dr Dinny Graham and her team were recently funded to investigate better treatments for women with triple negative breast cancer by identifying a hormone receptor that can be targeted with an effective therapy.

The two best known breast cancer hormone receptors are members of a large family of nuclear receptors. Dr Graham aims to find another nuclear receptor that can act as a unique biomarker for triple negative breast cancers.

Once they have identified the new receptor, the research team aims to develop a personalised test that can more accurately predict the outcome of treatment options and lead to new more effective treatments that target specific features of triple negative breast cancer.

This research represents future developments in personalised medicine which will reduce the mortality rate from triple negative breast cancer.

References

  1. https://theconversation.com/how-cancer-doctors-use-personalised-medicine-to-target-variations-unique-to-each-tumour-47349