Earlier breast screening in high-risk women shows 'encouraging' results
“Women with a family history of breast cancer should be screened in their thirties,” says The Daily Telegraph.
The news relates to an ongoing study that aims to look at the effects of mammography screening in women with a family history of breast cancer when they are between the ages of 35 and 39.
National guidelines currently recommend that women identified as being at increased risk of breast cancer because of a family history of the disease are offered annual mammography screening from the age of 40. Women at very high risk, such as those with BRCA1 or 2 mutations, are already offered annual MRI screening from the age of 30.
This report covers the first stage of the study, which looked back at the type of screening offered to women in this category at 33 centres across the UK. It found that the majority of the centres surveyed offered mammography, with most offering it on an annual basis.
In the five centres with the most rigorous follow-up, 47 cancers were identified in women, with almost half identified through screening and about a third identified between mammograms.
Comparison of these cancers with results reported in previous studies in unscreened women suggested that in the women offered screening, the cancers identified were smaller and less likely to have spread to the lymph nodes at the time of diagnosis.
The current study gives a snapshot of existing surveillance measures in the UK for women aged 35-39 who have an increased risk of breast cancer because of their family history. But as the centres surveyed were not specifically collecting information in order to analyse the effectiveness of mammography screening, they did not have enough information for a thorough analysis.
Therefore, the second part of this study plans to follow 2,800 high-risk women offered mammography screening on an annual basis up to 2016. These results will give a better idea of the potential benefits, risks and costs of screening in this younger age group.
Where did the story come from?
The study was carried out by researchers from the Genesis Breast Cancer Prevention Centre at the University Hospital of South Manchester NHS Trust and other hospitals and research centres in the UK.
The Daily Telegraph’s headline doesn’t convey the preliminary nature of these findings, but it does report later on in the story that a larger study is planned and that changes to recommendations are only likely if the larger study confirms the results.
What kind of research was this?
The researchers were reporting on part of a study of breast cancer screening in younger women with a family history of breast cancer (the FH02 study). The first part of the study was a retrospective analysis of the type of breast cancer surveillance that has been offered to these women in the past and what their outcomes were.
In the UK, all women between the ages of 50 and 70 are currently offered mammography. Women whose family history indicates that they are at increased risk are offered annual mammograms from the age of 40 as a form of “surveillance” for the disease. Women at very high risk, including those who are known to carry mutations in one of the BRCA1/BRCA2/TP53 genes, are offered annual MRI screening from the age of 30.
The researchers report that a previous study looked at mammography for women aged 40-49 in the UK with a significant family history of the disease (the FH01 study), but the effects of mammography in women aged 35-39 has not yet been assessed.
The National Institute for Health and Care Excellence (NICE) has produced guidelines on how doctors should classify breast cancer risk in women with a family history of the disease, and how they should be assessed and treated.
The researchers state that in the second part of this study, they will carry out a prospective study to look at the effects of breast cancer surveillance in these younger women. A previous study suggested that the health professionals caring for these women feel that such surveillance is likely to be of benefit. For this reason, it was decided that it would not be ethical to carry out a randomised controlled trial and that the study would compare the participants’ results with those from previous studies instead.
What did the research involve?
The researchers sent a survey to the 33 centres taking part in the study. The survey asked whether they had previously carried out mammographic surveillance in women under the age of 40 with an increased familial risk of breast cancer.
If they answered yes, the survey then asked about exactly how they selected women for surveillance and what this consisted of. They also asked about the outcomes of this surveillance, including the number and type of cancers identified.
The researchers compared these results with the types of cancer reported in studies published previously looking at women:
- aged 40-49 years with a family history of breast cancer who had annual mammography (the FH01 study)
- aged 40-49 years with a family history of breast cancer
- a series of women aged 30-49 having breast cancer surgery
- women aged 35-39 years with a family history of breast cancer who had not been screened
The researchers reported in detail the planned approach for their prospective study. This study aims to identify the likely benefit of annual mammography for women aged 35-39 with a family history of breast cancer.
They will compare the results in this group with results from the preceding study in older women with a family history of the disease (the FH01 study) and the UK Age Trial, a randomised controlled trial that assessed the effects of annual mammography screening in women from the age of 40 (not selected on the basis of family history). This study will also assess the cost of surveillance, so it can estimate its cost effectiveness.
The researchers say they have recruited 2,280 women from 33 centres, and should have reached the target of 2,800 by the end of June 2013. The study is expected to continue until June 2016.
What were the basic results?
In their survey, the researchers found that among the 33 centres:
- mammography screening in women aged 35-39 at increased risk of breast cancer was already carried out in 27 centres
- almost all of this screening was reported to use film mammography, rather than the newer digital mammography
- these 27 centres record a three generation family history and carry out a risk assessment in these women to determine their risk level
- 25 of the centres record the women’s lifetime risk of cancer and 22 record whether they have the known genetic mutations which predispose women to breast cancer (BRCA1, BRCA 2 and TP53)
- 26 of the centres offered the women annual mammograms and one centre offered them screening every two years
- 17 centres offered MRI scanning
- 14 centres offered routine physical examinations
- none of the centres routinely offered ultrasound
Five centres had robust systems to reliably identify whether any breast cancers were identified in these women in the period between mammograms (called interval cancers), as well as any detected in the mammogram.
There were 47 breast cancers in the women attending these centres between 1994 and 2010. Ten of these cancers (21%) were already known when the women attended the centres, 22 were new cancers (47%) identified through screening, and 15 (32%) were detected between mammograms.
Compared with two groups of unscreened women with breast cancer – one who had a similar family history and one without a family history – the cancers among the screened women were significantly smaller and less likely to have spread to the lymph nodes.
More of the screened women were alive with no spread of the disease in the screened group than in the two groups of unscreened women with breast cancer. However, the number of deaths from breast cancer was too small to carry out a robust analysis.
How did the researchers interpret the results?
The researchers say that this is the first study to assess the effects of mammography alone in women aged under 40 who are at increased risk of breast cancer.
They say that the results are “encouraging”, but that the prospective part of their study is needed to assess the effects of digital mammography in moderate and high-risk women in order to inform cost effectiveness analyses.
The current study gives a snapshot of existing surveillance measures in the UK for women aged 35 to 39 with an increased risk of breast cancer due to their family history.
There are some points to note, which the authors themselves highlight:
- As this first part of the study is retrospective, the centres will not have collected all the relevant information that would allow thorough evaluation of the effects of mammography.
- The number of cancers in women receiving screening described in detail in the current study is small (just 47). The larger prospective part of the study is needed to get better estimates of the rates of cancer in these women.
- Most previous screening in the centres used film mammography, but the newer technique of digital mammography may offer better results.
- In addition, the comparisons performed in the current part of the study against results in other studies may be affected by differences between the groups of women other than the screening offered. For example, the studies covered different time periods, and breast cancer management may have differed over these periods and could affect the chances of survival.
Overall, the current study gives some background information, but the second part of the study will shed more light on the potential effects of mammography surveillance in younger women at increased risk of breast cancer.