A new study from Denmark shows that people who suffer from cancer when they are children are more likely to develop mental health problems when they are adults. The study also found that the young siblings of children with cancer are at greater risk for mental health problems than the general population. The study was published in August 2013 in the journal Lancet Oncology. The lead author was Dr. Lasse Lund of the University of Copenhagen and the Cancer Society Research Centre. From 1975 to 2010, Dr. Lund\u2019s team kept track of 7,085 Danish people who were treated for cancer when they were children. The team also tracked 13,105 siblings of the children treated for cancer during these 35 years. Increased Risk for Cancer Survivors Using psychiatric registry data, the team found that 494 childhood cancer survivors (7 percent of the study population) received some form of either inpatient or outpatient treatment for a mental health disorder during the course of the study. In all, the data from the study showed a 50 percent greater incidence of mental health problems among the male survivors of childhood cancer than is seen in the general population, and a 26 percent increase in mental health disorders among the women. The study also showed that the age at which children are diagnosed with cancer seems to make a difference in their risk for mental health problems. Children who were diagnosed when they were younger than age 10 had a greater risk of a mental disorder than children who were diagnosed later. Men had a greater risk of depression if their cancer diagnosis came before age 10. An Increased Risk for Some Siblings Of the 13,105 siblings who were tracked during the study, 1,066 (8.1 percent of the study population) received treatment for a behavioral, emotional or neuro-developmental problem. As with the cancer survivor population, Dr. Lund\u2019s study showed that age affected the likelihood that a sibling of a child with cancer will develop a mental disorder. Although the sibling population overall had an increased risk of mental health problems, this risk shifted significantly among older siblings. In one of the more surprising results of the study, Dr. Lund\u2019s team found that siblings who were age 15 or older when their brother or sister was diagnosed actually had a decreased risk of developing a mental disorder compared to the general population. Old and New Findings A past Danish study looking at mental health disorders among childhood cancer survivors also found an increased risk for this population. However, the data from the earlier study showed increased risk for survivors of central nervous system cancers only. In contrast, the study led by Dr. Lund found increased risk for survivors of all forms of cancer, including leukemia, which are the most common kinds of cancer in children. The more recent study was larger and longer, and, as a result, may represent a more accurate picture of what goes on in the larger population of childhood cancer survivors. Future studies will look to confirm the findings from Dr. Lund\u2019s study, and continue to explore the relationship between cancer and mental health. Doctors have long suspected a relationship between chemotherapy and an increased risk of severe mental health disorders such as bipolar disorder and schizophrenia, but more research is required before these suspicions are confirmed. A Growing Problem Mental health problems are a growing concern among childhood cancer survivors, for a very good reason. Prior to the 1970s, fewer than 50 percent of the children diagnosed with cancer survived for five or more years after receiving their diagnosis. In the past four decades, that percentage has grown steadily to about 80 percent. This has resulted in a much larger population of cancer survivors. In that respect, it is a good problem to have. But this does not mean that the study findings are not serious, since undiagnosed and\/or untreated mental disorders can be fatal. Speaking to Reuter\u2019s Health, Dr. Lund has said that he hopes his research and other research like it will encourage programs to track the mental health of cancer survivors in addition to their physical health.