The Presence of cancer in one twin increases the risk of the disease in the other, a study has shown.

The study, published in the Journal of American Medical Association this week, points out that since twins share the same genes, having cancer in one subjects the other to a higher risk of getting sick but does not necessarily mean that when one twin falls ill, the other gets that cancer or any other type.

Studies show that twins account for over 90 per cent of multiple births with the two types being identical and fraternal.

Identical twins develop from one fertilised egg (ovum) splitting to form two babies with exactly the same genetic information, whereas fraternal twins or non-identical twins usually occur when two fertilised eggs are implanted in the uterine wall – at the same time – that is when the mother releases two eggs and both become fertilised by two different sperms.

The new study that involved 200,000 people, found the risk of cancer was 14 per cent higher in identical pairs in which one twin was diagnosed with cancer, whereas in fraternal twins, the risk was five per cent higher in a twin whose other twin was infected.

These studies were conducted in twins within Denmark, Finland, Sweden and Norway between 1943 and 2010.

When researchers looked at the group as a whole, about one in three individuals developed cancer (32 per cent).

And the risk of cancer in an identical twin whose twin was diagnosed was calculated to be 46 percent, whereas in fraternal twins it stood at a 37 per cent risk of developing cancer if a co-twin was diagnosed.

The same cancer was diagnosed in 38 per cent of identical twins and 26 per cent of fraternal pairs.

Cancers that were most likely to be shared among twins were skin melanoma (58 per cent), prostate (57 per cent), non melanoma skin (43 per cent), ovary (39 per cent), kidney (38 per cent), breast (31 per cent), and uterine cancer (27 per cent).

"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.

According to the World Health Organisation, cancers are among the leading causes of morbidity and mortality worldwide, with approximately 14 million new cases and 8.2 million cancers related deaths in 2012.

In Rwanda, figures from Butaro Centre show that since July 2012, 241 children cancer patients were received.

However, figures could be higher since some die before reaching the hospital, according to experts.

"In Rwanda the cancer of the kidney is the leading case followed by different blood cancers, including acute lymphoblastic leukemia, Hodgkin’s and Non-Hodgkin lymphomas,” Dr Fidel Rubagumywa, the director of the Rwanda Children’s Cancer Relief (RCCR), told The New Times.

editorial@newtimes.co.rw