More severe breast cancer among immigrant women
New research from the Cancer Registry of Norway shows that immigrant women attend mammography screening less often than Norwegian-born women, and those who attend more often need additional examinations than the Norwegian-born. Nevertheless, breast cancer is less often detected.
"At the same time, immigrant women more often have more severe breast cancer if they are first diagnosed with the disease," says Sameer Bhargava, who is a PhD candidate at the Cancer Registry of Norway and first author of the article.
Immigrant women receive the same recommendations to participate in mammography screening as Norwegian-born women. That is, they receive a general recommendation - and offer - to participate in the Public Mammography Programme every two years when they are aged 50 to 69.
Now, the new study from the Mammography Programme shows that the screening programme is perhaps less accurate for some groups of immigrant women than it is for Norwegian-born women.
The study, conducted at the Cancer Registry of Norway, was published in the journal European Radiology in February 2019 and has compared quality indicators in the Mammography Programme among immigrant women and Norwegian-born women.
More than 3 million screening examinations and more than 750 000 women were included in the study, of which about 50 000 had an immigrant background.
The study is funded by Extrastiftelsen.
More additional examinations and more serious breast cancer in immigrant women
The results show, among other things, that more immigrant women than Norwegian-born women must be called back to take new mammography images, ultrasound or needle samples of the breast in order to make a definite assessment of whether they have breast cancer or not - even though fewer of them are eventually diagnosed with breast cancer.
At the same time, the research group also made findings indicating that immigrant women more often than Norwegian-born women develop breast cancer that is associated with a poor prognosis.
" Among other things, we compared the type of breast cancer detected between screening examinations – so-called interval cancer – in the two groups, and saw that a higher proportion of immigrant women than the Norwegian-born got interval cancer of a type we call triple negative breast cancer in medical terms, which is associated with a poorer prognosis. explains Bhargava
According to Bhargava, they also found that the cases of breast cancer detected by the screening examinations were more often larger (over 2 cm) and high-grade among immigrant women than among Norwegian-born women.
This may indicate more aggressive disease among immigrant women, but - probably because of few cases of cancer in the data set - the differences were not statistically significant.
The findings applied in particular to immigrant women with backgrounds from countries where breast cancer is less common than in Norway, i.e. countries in Africa, Asia, Eastern Europe, South and Central America and Oceania except Australia and New Zealand.
The differences were still present even when the analyses took into account that X-ray doctors had earlier mammography images available to immigrant women to a lesser extent than for the Norwegian-born. Previous images are often useful to the doctor when suspicious findings are to be assessed.
The differences were also retained when the analyses took into account that immigrant women who attend mammography screening are on average younger than Norwegian-born, because fewer have managed to be old enough to be included in the programme.
The same screening programme for everyone?
Bhargava questions whether the Norwegian screening programme is sufficiently accurate for all groups of immigrant women.
"This study, combined with previous research, may indicate that immigrant women from countries with a low incidence of breast cancer may benefit from starting and stopping mammography screening earlier than Norwegian-born women, and perhaps also that they may benefit from being screened more frequently than every other year," says Bhargava.
He believes that much knowledge is still needed before it can be realistic to make various recommendations on mammography screening for immigrant women and Norwegian-born women. Among other things, studies are needed that investigate inequalities in breast cancer survival, and how much of the inequalities can be explained by lower attendance among immigrant women.
He also points out that it is important to know more about how much of the observed differences can be explained by lifestyle differences, such as the use of hormone preparations or the number of children one has children, and how much may be due to biological differences.
In addition, he points out that offering screening to different age groups and intervals to immigrants and Norwegian-born women is complicated by the fact that immigrants' risk of breast cancer is expected to become more similar to Norwegian-born women's risk the longer the period of residence immigrant women have in Norway.
According to Bhargava, measures to increase attendance in the Mammography Programme among groups of immigrant women will be an important first step towards increasing the performance of the screening programme for these groups.
Want a holistic approach and good information
Solveig Hofvind, professor and head of the Mammography Programme, is the project manager and main supervisor for Bhargava. She agrees with Bhargava that the screening programme may have the potential to be more accurate for groups of immigrant women, but also points out that accuracy is not optimal for other groups either, and that thorough cost-benefit evaluations are necessary before any changes can be made to the Mammography Programme.
" Immigrant background is one of several factors that must be considered if the screening programme is to be adapted," says Hofvind.
She explains that there are several groups, such as women with mammographically dense breasts, i.e. a lot of dense glandular tissue, who may also benefit from a more adapted screening programme, and that changes must be assessed with a holistic approach.
She also points out that there is already an ongoing discussion in the academic communities about whether the programme should be expanded for everyone, regardless of immigrant background.
" According to both the World Health Organization and the professional communities in the EU, the knowledge base for screening the age groups 45-49 years and 70-74 years has been significantly strengthened in recent years," explains Hofvind, adding that it is of course also an economic question of what the health authorities will prioritize.
Although Hofvind would like to envisage a more adapted mammography programme in the longer term that takes into account several different factors such as the type of breast tissue a woman has, breast cancer incidence in the family, immigrant background and more, here and now she is also concerned with good information – both for the groups of women this applies to and to health personnel.
"The mammography programme mainly includes young immigrant women, who are largely invited for the first time. Available information about breast cancer and the screening programme are probably key factors in getting them to attend screening," says Hofvind.
"We need to communicate the knowledge we have now researched, so that both the women themselves and the health personnel they are in contact with are aware that, for example, age and risk of breast cancer may differ from Norwegian-born women".
The Cancer Registry of Norway and the Mammography Programme, in collaboration with various expert communities that carry out health work for the immigrant population, have started work to improve the facilitation of information for groups of immigrant women, and hope that in the long term this will yield results in the form of increased awareness and knowledge, and higher attendance in the programme.
