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There are at least 22 different types of cancer that are triggered by genetics - and passed down through families, a new study has revealed.
Harvard scientists, working with colleagues in Denmark and Finland, have discovered those forms of the disease with the highest 'excess familial risk'.
They include prostate, breast, lung and colon, their findings show.
Furthermore, scientists found that a person has a 33 per cent risk of developing some form of cancer if one of their siblings is diagnosed with the disease, the researchers said.
The scientists examined the familial risk of cancer in sets of twins.
They discovered that having a twin sibling diagnosed with cancer increases a person's risk of developing the disease themselves.
And, their findings rang true for both identical and non-identical twins.
The discovery in non-identical twins, they said, suggests the risk is also prevalent in siblings that are not twins, given the genetic differences.
Co-lead author of the study, Jacob Hjelmborg, of the University of Southern Denmark, said: 'Because of this study's size and long follow-up, we can now see key genetic effects for many cancers.'
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The study, by researchers at Harvard, the University of Southern Denmark and the University of Helsinki, is the first to provide family risk estimates for these and other, rarer cancers.
It also reveals, for the first time, that in twin pairs where both developed cancer, each twin was often diagnosed with a different form of the disease.
Researchers said this suggests that, in some families, there is a shared increased risk of any type of cancer.
Because of this study's size and long follow-up, we can now see key genetic effects for many cancers Jacob Hjelmborg, study co-lead, of the University of Southern Denmark
Lead author, Dr Lorelei Mucci, an associate professor of epidemiology at Harvard Chan School, said: 'Prior studies had provided familial risk and heritability estimates for the common cancers - breast, prostate and colon.
'But, for rarer cancers, the studies were too small, or the follow-up time too short, to be able to pinpoint either heritability or family risk.'
Familial risk of cancer is a measure of the cancer risk faced by an individual.
The study also assessed the heritability of cancer - a measure of how much of the variation in a population's cancer risk is due to genetic factors.
Researchers looked at more than 200,000 twins, both identical and fraternal (non-identical), in Denmark, Finland, Norway and Sweden, who took part in the Nordic Twin Study of Cancer.
They were followed by scientists for an average of 32 years, from 1943 to 2010.
Large twin studies, such as this, as useful to scientists, allowing them to assess the importance of inherited factors in cancer, and assess familial cancer risk by taking into account how genetically similar identical and non-identical twins are.
Overall, researchers found one in three people taking part developed cancer over the course of a lifetime.
Cancer was diagnosed in both twins for 3,316 of the pairs.
Of those pairs, the same cancer was diagnosed in 38 per cent of identical twins and 26 per cent of non-identical twins.
The scientists estimated when one non-identical twin was diagnosed with any form of cancer, the co-twin's risk of developing the disease was 37 per cent.
In identical twins the risk jumped to 46 per cent.
One of the strongest familial risks was found in cases of testicular cancer.
Researchers found that a man's risk of developing the disease was 12 times higher if his non-identical twin was diagnosed with it.
And for identical twins the risk was 28 times higher for the healthy twin if one of the pair was diagnosed.
The scientists noted that non-identical twins are similar genetically to siblings who are not twins.
As a result, the finding of excess cancer risk in non-identical twins does suggest an increased cancer risk for families where one sibling is diagnosed with cancer.
Overall, the findings show the heritability of cancer was 33 per cent.
Significant heritability was found for skin melanoma (58 per cent), prostate cancer (57 per cent), non-melanoma skin cancer (43 per cent), ovarian cancer (39 per cent), kidney cancer (38 per cent), breast cancer (31 per cent) and uterine cancer (27 per cent).
Co-senior author of the study, Jaakko Kaprio, from the University of Helsinki, said: 'Findings from this prospective study may be helpful in patient education and cancer risk counselling.'
The study was published online in JAMA.
A DISEASE THAT RUNS IN THE FAMILY
The heritability of specific types of cancer is well known, and some celebrity families have had their battles with the disease well documented.
TV cook Nigella Lawson lost both her mother and sister to different types of cancer (liver and breast respectively).
And tragically the chef also lost her first husband, journalist John Diamond, to throat cancer in 2001.
Furthermore Hollywood actress Angelina Jolie has taken preventative steps against cancer after the death of her mother Marcheline Bertrand.
The star, who has six children with Brad Pitt underwent a double mastectomy and had her ovaries removed, after learning she is a carrier of the BRCA mutation, that increased her risk of breast cancer by around 87 per cent.
The mutation also increases the risk of ovarian cancer.
The Hollywood star revealed in 2015 that no fewer than eight family members, including her mother, cousin, aunt, great aunt, grandfather, uncle, grandmother, and great-grandmother all died of different forms of the disease.
