What is triple-negative breast cancer?
You may have heard that cancer is not a single condition – and this is very true for breast cancer, too.
There are many types of breast cancer. “Triple-negative” breast cancer is one of them, and is estimated to make up 10-20% of all breast cancer diagnoses.
Its name is based on specific proteins and hormones that describe the pathology of the tumour. These substances affect what kinds of therapies can be applied effectively. Could they also indicate the diet that we should follow to help our body and the treatment? Many researchers have been trying to answer this exact question.
Before we get to that, however, let’s explore the nature of triple-negative breast cancer.
Oestrogen, progesterone, and HER2
These are the three substances behind “triple-negative”.
Oestrogen & progesterone are hormones. Some of our cells have “receptors” (proteins) that these hormones attach to, and fuel them.
- Some breast cancer cells may not have these receptors (or have very few of them).
- These tumours are called “oestrogen-receptor negative” & “progesterone-receptor negative”, respectively.
- You may also read/hear the terms as “ER-” & “PR-“.
- Given their lack of receptors, these tumours would not respond to hormone therapy.
HER2 is a protein in our body.
- Sometimes, a gene may result in excessive production of this protein. This may make cancer cells grow and spread faster. In this situation, called HER2-positive, treatments try to stop this function.
- In the case of HER2-negative breast cancer cells, however, this means that this protein is not produced in large amounts. (You may also find this situation named as “underexpression of HER2”.)
- In turn, this means that treatments targeting this function will not affect HER2-negative tumours.
- It is important to note that you do not necessarily inherit this gene mutation from your parents, and you do not pass it on to your children.
Is the best diet for triple-negative breast cancer related to hormones and proteins?
As mentioned, these hormone receptors, as well as HER2, are proteins. However, please note that this does not imply any association with our protein intake.
However, because of their chemical characteristics, they seem to make a difference in the biology of the tumour. It also seems that eating, or avoiding, specific foods or ingredients could affect how this particular breast cancer type evolves. Similar research is investigating potential links with vitamins and supplements as well.
Research on foods affecting triple-negative breast cancer
There are no specific scientific guidelines for this type of breast cancer in terms of nutrition. On the other hand, extensive research has been conducted in order to identify potential recommendations. Here we will present some of this research, but please note that it is inconclusive and does not imply recommendation.
- UCLA researchers studied 2,400 women and found that maintaining a low-fat diet led to better survival outcomes in some subtypes, including triple-negative.
- In particular, scientists divided the women in two groups, and those in one group followed a specific diet. The diet did not aim at a weight loss, but had as its goals to receive less than 20% of daily calories from fat. For the group that followed this diet, the outcome was beneficial on many levels: firstly, they lost an average of 6 pounds in 5 years. But more importantly, some of the women following this diet also had better medical outcomes. In particular, women with oestrogen-receptor and progesterone-receptor negative breast cancer had 54% improvement in overall survival.
- While the role of the HER2 protein was not examined, researchers expect many of these women to also have HER2-negative cells (which would mean their breast cancer is triple-negative).
- You can read the report from the 2014 San Antonio Breast Cancer conference for more information.
Omega-3 fatty acids
- At the 2013 American Association for Cancer Research conference, researchers presented findings that omega-3 fatty acids slow down triple-negative breast cancer. Foods rich in omega-3 fatty acids include sardines, tuna, trout, salmon, as well as flax and hemp, etc. In particular, when omega-3 reaches our cells, it is divided into components that affect cells in many ways.
- Research showed that when omega-3 reaches triple negative breast cancer cells, it reduces their activity: it slows down their growth or even stops it altogether. This may mean that omega-3 can help the overall treatment of these tumours.
- You can read a news release about the findings to find out more, if interested.
- In 2015, research showed that reducing/eliminating dietary intake of “methionine” can help targeted antibody treatment for triple-negative breast cancer patients.
- Methionine is an essential nutrient in meat, fish, some legumes and nuts; fruits and vegetables have limited amounts.
- Researchers discovered that when triple-negative breast cancer cells do not get enough of this substance, they become more sensitive to a specific antibody. This means that if this antibody attaches to their surface, it can kill them. It was also important that the non-cancer cells did not have this reaction – and this surprised scientists.
- There is no approved treatment today that uses this specific antibody. However, if future clinical trials show it can work, it may help against this hard-to-treat cancer. As Vincent Cryns (the study’s senior author) commented, their research “shows that diet can help expose a targetable defect in cancer cells”.
- The research, which was conducted on mice, took place in the University of Wisconsin-Madison, and its School of Medicine and Public Health in particular. If interested, feel free to read an article about this research.
Please note that some of the above were based on pre-clinical research (i.e. not on clinical trials or other research involving humans).
As always, please consult your medical team when considering specific changes to your diet against your type of breast cancer.
What do these mean for me?
This is important research, but there is no single approach that would help anyone diagnosed with breast cancer. Actually, everyone is different, and the details of our diagnosis play an important role in shaping the best diet to get through cancer.
Furthermore, different treatments work in different ways, making it very difficult for any one single approach to work for everyone.