A trial comparing different ways of giving radiotherapy for women with ductal carcinoma in situ of the breast (BIG 3-07)

The research team found that extra radiotherapy to a specific area of the breast may help stop DCIS coming back.

Trial design
This trial was for women who’d already had an area of ductal carcinoma in situ (DCIS) removed from their breast. Everyone taking part had radiotherapy.

The women were put into 1 of 4 treatment groups at random:

• group 1 had standard radiotherapy to the whole breast
• group 2 had shorter course radiotherapy to the whole breast
• group 3 had standard radiotherapy to the whole breast and then radiotherapy to the area where the cancer was (a boost)
• group 4 had shorter course radiotherapy to the whole breast and then radiotherapy to the area where the cancer was (a boost)

Diagram 1

Radiotherapy is measured in Gray (Gy). You have a total dose of radiotherapy split into smaller doses called fractions.

In this trial:

• standard radiotherapy was 50Gy in 25 fractions
• shorter course radiotherapy was 42.5Gy in 16 fractions
• the radiotherapy boost was 16Gy in 8 fractions

So the women who had the shorter course of radiotherapy had a higher amount in each fraction, but a lower dose overall. This is called hypofractionated radiotherapy.

Results
More than 1,600 women joined this trial.

The research team compared those who had standard radiotherapy with those who didn’t. And they compared those who had a radiotherapy boost with those who didn’t. 

They looked at how many people’s DCIS had come back in the breast, 5 years after radiotherapy. They found it was less than 1 out of 10 people (less than 10%) in all groups:

• 6% of those who had standard radiotherapy
• 6% of those who had shorter course radiotherapy
• 4% of those who had a radiotherapy boost
• 8% of those who didn’t have a radiotherapy boost

Bar Chart 1

They also looked at how many people were living, 5 years after treatment. They found it was nearly the same in all groups. It was either 97 or 98 out of 100 (97% or 98%) in each group.

Side effects 
Some people had side effects caused by radiotherapy:

• nearly 6 out of 10 people (57%) who had standard radiotherapy
• more than 4 out of 10 people (43%) who had shorter course radiotherapy
• nearly 6 out of 10 people (58%) who had the radiotherapy boost
• more than 4 out of 10 people (43%) who didn’t have a radiotherapy boost

Many of these were mild or didn’t last long. A small number of people in each group had more severe side effects. 

The most common side effects were sore skin, hardening of breast tissue (induration), breast pain and extreme tiredness (fatigue). All of these affected a few more people who had standard radiotherapy or the radiotherapy boost.

We have more information about the side effects of radiotherapy to the breast in our Breast cancer section. 

Quality of life
Everyone taking part was asked to fill out quality of life questionnaires before and after treatment. These included questions about how the women were feeling and any side effects they were having. They also asked about the appearance of their breast and how they felt about it.

The results showed that women in all groups were less happy about the appearance of their breast after radiotherapy. And this affected how they felt about their bodies. This was the case for more women who had the radiotherapy boost than those who didn’t. 

Women in all groups also had issues with arm and shoulder movement after radiotherapy. Again, this was the case for more women who had the radiotherapy boost.

The other factors used to measure quality of life were similar in all the groups.

Conclusion
The trial team concluded that a radiotherapy boost to a specific area of the breast could help stop DCIS coming back. This is for women who’ve had surgery to remove the area of DCIS, followed by radiotherapy to the whole breast. 

They also concluded that fewer doses of radiotherapy to the whole breast could be a useful treatment option for this group of women. They found that having a radiotherapy boost can affect people’s body image, and arm and shoulder movement.

More detailed information
There is more information about this research in the references below. 

Please note, these articles are not in plain English. They have been written for health care professionals and researchers.

Journal articles
Quality of life after breast-conserving therapy and adjuvant radiotherapy for non-low-risk ductal carcinoma in situ (BIG 3-07/TROG 07.01): 2-year results of a randomised, controlled, phase 3 trial
M King and others
The Lancet Oncology, 2020. Volume 21, Issue 5, pages 685 - 698

Radiation doses and fractionation schedules in non-low-risk
ductal carcinoma in situ in the breast (BIG 3–07/TROG 07.01):
a randomised, factorial, multicentre, open-label, phase 3
study 
B Chua and others
The Lancet, 2022. Volume 400, Issue 10350, pages 431 - 440

Where this information comes from    
We have based this summary on the information in the articles above. These have been reviewed by independent specialists (peer reviewed ) and published in medical journals. We have not analysed the data ourselves.