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RESEARCH

Nordic twins help reveal higher cancer risks

A comprehensive study of twins in Denmark, Norway, Sweden and Finland has led to new revelations about increased cancer risks among siblings.

Nordic twins help reveal higher cancer risks
If one twin gets cancer, the other has a higher risk of getting sick too. Photo: Colourbox
Twins share the same genes, and when one gets cancer, the other faces a higher risk of getting sick too, according to a study published on Tuesday that included 200,000 people.
 
But just because one twin falls ill does not mean that the other is certain to get the same cancer, or any cancer at all, according the report in the Journal of the American Medical Association (JAMA).
 
In fact, the amount of increased risk of cancer was just 14 percent higher in identical pairs in which one twin was diagnosed with cancer.
 
Identical twins develop from the same egg and share the exact same genetic material.
 
Among fraternal twins, which develop from two eggs and are as genetically similar as typical biological siblings, the risk of cancer in a twin whose co-twin was infected was five percent higher.
 
The twins in the study hailed from Denmark, Finland, Sweden and Norway — all countries that maintain detailed health registries — and were followed between 1943 and 2010.
 
When researchers looked at the group as a whole, they found that about one in three individuals developed cancer (32 percent).
 
Therefore, the risk of cancer in an identical twin whose twin was diagnosed was calculated to be 46 percent.
 
In fraternal twins it amounted to a 37 percent risk of developing cancer if a co-twin was diagnosed.
 
The exact same cancer was diagnosed in 38 percent of identical twins and 26 percent of fraternal pairs.
 
The cancers that were most likely to be shared among twins were skin melanoma (58 percent), prostate (57 percent), non melanoma skin (43 percent), ovary (39 percent), kidney (38 percent), breast (31 percent), uterine cancer (27 percent).
 
“Because of this study's size and long follow-up, we can now see key genetic effects for many  cancers,” said Jacob Hjelmborg, from the University of Southern Denmark and co-lead author of the study.
 
Researchers said the findings may help patients and doctors understand more about the hereditary risks of cancer, a disease that kills eight million people around the world each year.

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RESEARCH

Not so gender-equal? Swedish teens still plan careers according to gender, study shows

Swedish teenagers’ plans for their future careers are heavily influenced by their gender, a new study shows, and girls' doubts over their abilities to succeed in male-dominated sectors are a decisive factor.

Not so gender-equal? Swedish teens still plan careers according to gender, study shows
File photo of a Swedish high school class. Photo: Berit Roald / NTB scanpix / TT

Both boys and girls are reluctant to enter professions dominated by the opposite gender, leading to gender segregation later on in the world of work, the study from Lund University shows. 

“We already knew that there's a large gender segregation in Sweden, but what we didn't expect to find was that girls still under-estimated their abilities in masculine stereotyped areas such as technology,” Una Tellhed,  who was project leader on the study, told The Local.

“Girls also underestimated how well they thought they would do in male-dominated professions such as engineering. Since Sweden is one of the most gender-equal countries in the world, we were hoping that maybe our 15-year-old girls would have moved past these stereotypes, but they're still alive and kicking!”

Researchers interviewed 2,600 15-year-olds for the study, at which age Swedish children begin choosing the subjects they will study in upper secondary school, which can be decisive for their future career.

Both boys and girls were less likely to choose subjects associated with the opposite gender, due to a range of factors, including their personal priorities (for example, whether they valued helping others over achieving high social status), concerns over fitting in within certain sectors, and perceptions of their ability to succeed in certain areas.

But among girls, Tellhed said that belief in their own abilities was the most important variable, followed by worries about fitting in. “Girls were slightly more likely to prioritize helping others over achieving a high status in their career than boys, but this had only a very small influence compared to these other factors,” she explained.

READ ALSO: Gender segregated school bus not discriminatory, Swedish equality watchdog rules

Meanwhile, boys typically thought they would be able to do equally well in male-dominated and female-dominated fields. Like girls, however, they worried they would be less well accepted in a sector dominated by the other sex.

Tellhed hopes her research will be valuable in tackling gender segregation in Sweden's workforce, something she believes will benefit both Swedish society and individuals.

“We need more men to take an interest in nursing and more women to take an interest in technology, partly because it's important for the labour market to be able to recruit both men and women,” she said.

“But it's also a problem because men and women are more similar than they are different psychologically, so it's sad that people may not find the career that would match them best, just because it's not associated with their gender. Hopefully we will start to talk more about gender similarity instead of gender difference.”

Finding out which factors lead to gender segregation can help the government and educators tackle it more effectively, and encourage children to consider less gender-typical occupations.

“So now we know that ability-belief is the most important factor for women, we can work on ways to strengthen this self-belief. For men, we need to find out if it would be more efficient to raise the status of nursing to make it more attractive to them, or to try to make boys more interested in helping others — this needs more research,” Tellhed explained.

READ ALSO: Sweden to ban single-sex classrooms