By Jeremy Laurance
London - Cancer is rising rapidly among children across Europe and the increase shows no sign of slowing, researchers have found.
The rate of the increase - up 17 percent over 20 years - is too large to be accounted for by improvements in detection and is worrying specialists. They say different cancers have different causes and one factor cannot be responsible for all. But modern lifestyles and changes in the environment are likely to be behind the rise.
The study examined 77 111 cases of cancer in children diagnosed between 1978 and 1997 in 15 European countries. More than 23 000 cases were from Britain. The results showed that the number of cases of cancer in children aged 0 to 14 rose by 1,1 per cent a year on average. There were increases in most childhood cancers including brain tumours, testicular cancer, leukaemia, kidney cancer and soft tissue sarcoma (cancer of connective tissue). There was no increase in bone cancer, liver cancer or retinoblastoma.
The trend towards later parenthood, heavier birth-weights and the reduction in infant mortality are thought to be factors behind the rise. Vulnerable babies with a genetic predisposition to cancer who would have died a couple of decades ago are now surviving to develop the disease.
The incidence of childhood cancer in Britain increased from 114,5 cases per million in 1978 to 134 in 1997, a rise of 17,5 percent. But the researchers found that in each successive five-year period, the rate was higher than in the previous five years. In Europe, the rate rose from 120 cases per million in 1978 to 140 in 1997.
The findings are published in the European Journal of Cancer. The study's authors, from France, Germany and Italy, said: "The increased incidence can only partly be explained by changes in diagnostic methods and by registration artefacts. The magnitude of these increases suggest that other factors, eg, changes in lifestyle and in exposure to a variety of agents, have contributed to the increase in childhood cancer."
A study by the same authors published two years ago in The Lancet was criticised by specialists who said the increase could be accounted for by improvements in recording cases. For the new study, they narrowed the search to focus on the best statistics.
Eva Steliarova-Foucher, a senior epidemiologist at the International Agency for Cancer Research in Lyon, France, and an author of the study, said: "The rise may be partly due to better detection but not wholly. Other studies have shown older mothers have an increased incidence of leukaemia and certain other cancers in their children.
"Children are being born heavier and higher birth-weight has been linked with cancers such as leukaemia, Wilm's tumour and neuroblastoma."
Jamie Page, of the Cancer Prevention and Education Trust, said suspicion had fallen on environmental toxins as potential causes of childhood cancer, including pesticides, and phthalates in plastics.
"Cancer is not entirely a disease of ageing," he said. "It is misleading when the medical establishment tell us that. We need to put chemicals on the agenda."
Bruce Morland, paediatric oncologist at Birmingham Children's hospital and a scientist with Cancer Research UK, said: "There is a lot of interest in a possible environmental link but the sad thing is that we have been unable to pinpoint any one factor."
Geoff Thaxter, director of services at CLIC Sargent, the children's cancer charity, said: "This statistical analysis does suggest an increase in children's cancer and although part of this can be explained by improved registration, that is clearly not the full picture."
One third of all childhood cancers are leukaemia, involving about 400 new cases a year in the UK. Three out of four cases are acute lymphoblastic leukaemia; a quarter are acute myeloid leukaemia. UK incidence up from 39,3 (1978) to 43,5 (1997) per million, a 10,6 percent rise
The most common solid tumours that occur in children, affecting 350 a year in the UK, boys more often than girls. Incidence (central nervous system tumours) up from 25,6 to 31,9 per million, a rise of 24,6 percent
SOFT TISSUE SARCOMAS
Rare types of cancer that develop in any of the tissues that support or protect the organs in the body. There are about 80 cases a year. UK incidence up from 7,0 to 10,6 per million, a 51,4 percent rise
GERM CELL TUMOURS
Mostly affect the testes or ovaries. About 45 children a year are affected. UK incidence up from 3,7 to 4,1 per million, a 10,8 percent rise
Cancers of the glands in the neck, under the arms and in the groin. Hodgkin's and non-Hodgkin's lymphoma affect about 140 children a year. UK incidence up from 11,0 to 11,3 per million, a rise of 2,7 percent
The commonest kidney cancer in children is Wilm's tumour, accounting for four out of five cases. It affects about 70 children each year. UK incidence up from 7,3 to 7,8 per million, a rise of 6,8 percent