A study looking at the diagnosis and treatment of breast cancer in younger women with and without an inherited genetic change (POSH)

Between 2000 and 2008, this study recruited more than 3,000 women who had been diagnosed with breast cancer within the previous year. They were all aged 40 or less at diagnosis. The research team looked at the medical notes of the women taking part, to see how they were doing after treatment.

They looked at a number of characteristics of breast cancer, to see if any of them affected how well treatment worked. They have published several articles in medical journals, looking at some of these characteristics.

Below is a summary of the work they have done so far. We plan to update this page if they publish more results in the future.

In this summary we have results about:

• Oestrogen receptors
• Body weight
• Family history
• Assessment of PREDICT, an online tool
• Inherited genetic changes
• Other research

Oestrogen receptors
In 2013, the researchers published some results showing the effect of oestrogen receptor (ER) status. They analysed this for 2,956 of the women who took part. They looked at how many of the women lived for at least 5 years after diagnosis and found it was:

• 85% of women whose cancer had oestrogen receptors (ER positive breast cancer)
• 76% of women whose cancer didn’t have oestrogen receptors (ER negative breast cancer)

But when they looked at the number of women who lived for at least 8 years, they found this was about the same for both groups at about 68%.

Body weight
In 2014 the research team looked at the effect of body weight. They measured the body mass index (BMI) of 2,843 women, to work out whether the women were a healthy weight or not, and:

• 1,526 women (54%) were a healthy weight or underweight with a BMI of less than 25
• 784 women (27%) were overweight with a BMI of 25-29
• 533 women (19%) were obese with a BMI of 30 or more

The results showed that women who were classed as obese were:

• more likely to have a larger cancer
• more likely to have cancer that could grow and spread more quickly (grade 3 cancer)
• more likely to have cancer that had spread to a lymph node under the arm
• less likely to live as long after diagnosis

They concluded that women who were obese at diagnosis didn’t do as well as those who were a healthy weight.

Family history
In 2015 they published results looking at the effect of family history on how well women did. They analysed results for 2,850 women and found that:

• 66% had no family history of breast cancer
• 34% had at least one first or second degree relative with breast or ovarian cancer

They found that having a family history did slightly increase the risk of being diagnosed with a cancer that was likely to grow more quickly (grade 3 cancer).

But it didn’t affect:

• the size of the cancer
• the likelihood that the cancer had spread to the lymph nodes or to another part of the body at diagnosis
• how long the women lived for
• whether the cancer came back after treatment or spread to another part of the body

They concluded that having a family history did not affect how well younger women with breast cancer did after treatment.

Assessment of PREDICT, an online tool
PREDICT is an online tool that helps doctors and patients decide which treatment is best after surgery for breast cancer. It uses medical information to predict how much benefit people will get from different treatments.

In 2015 the research team used the information from women taking part in POSH to find out how accurate the PREDICT tool is. They compared the prediction to what actually happened.

They found that it:

• was good at predicting who would live for at least 8 and 10 years after diagnosis
• was less accurate at predicting who would live for at least 5 years
• over estimated how well people with oestrogen receptor (ER) positive cancers would do
• under estimated how well people with ER negative cancers would do

The researchers concluded that the PREDICT tool was useful for longer term predictions. It has since been updated to be more accurate for younger women with breast cancer, and a new version is now available for doctors to use.

Inherited genetic changes
In 2017, the researchers published some results looking at the effect of having an inherited change (mutation) in either the BRCA1 or BRCA2 gene.

Out of 2,733 women they found that:

• 201 women (8%) had cancer with a BRCA1 gene mutation
• 136 women (4%) had cancer with a BRCA2 gene mutation
• 2,396 women (88%) didn’t have a BRCA1 or BRCA2 gene mutation

The research team looked at how long women lived after diagnosis, and whether the cancer spread to another part of the body. They found it was about the same for those who had a genetic change and those who didn’t.

Younger women with breast cancer and a BRCA gene mutation sometimes decide to have surgery to remove both breasts (a double mastectomy), to help prevent the cancer coming back. This operation can be difficult for women to cope with, especially if they are young.

The research team suggest that it may not be necessary to have this surgery straight away. A small number of women in this study had a double mastectomy soon after diagnosis, but they didn’t do any better than those who decided not to. It could be an option for them to have surgery at a later date, depending on their situation.

They then analysed the results of the 558 women who had triple negative breast cancer. This means their cancer didn’t have receptors for the hormones oestrogen or progesterone, or the protein HER2. 

They looked at how many women with triple negative breast cancer were living at 2 years, 5 years and 10 years after diagnosis. They found that it was a bit higher for women with a BRCA gene mutation, compared to those with no mutation.

The difference between the two groups was biggest at 5 years, but smaller by 10 years. This suggests that women with triple negative cancer and a BRCA gene mutation may do a bit better in first few years after diagnosis. But it is difficult to say for sure.

Other research
As part of this study, the research team collected samples of blood and cancer cells so that they could be used for future research. They are all kept anonymously, no one taking part can be identified from their samples.

The genes in these samples have been analysed a number of times already, sometimes with samples collected as part of other studies. Research teams have been comparing samples to find specific genes that may affect why:

• some people develop breast cancer and others don’t
• chemotherapy after surgery works better for some people than others
• hormone therapy works better for some people than others
• some people with breast cancer live longer than others

They have also done some work looking at how the body uses and gets rid of tamoxifen, a hormone therapy. Researchers think that how the body deals with tamoxifen can affect how well it works. More work needs to be done, but they suggest that different people could benefit from different doses of tamoxifen in future.

Analysis of cancer cells and genes is complicated and takes a long time. But it will help us understand more about breast cancer, and help shape the diagnosis and treatment of people with breast cancer in the future.

We have based this summary on information from the research team. The information they sent us has been reviewed by independent specialists (peer reviewed ) and published in a medical journal. The figures we quote above were provided by the trial team who did the research. We have not analysed the data ourselves.