The Pharmaceutical Journal
Vol 269 No 7208 p125
27 July 2002

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The Lancet (www.thelancet.com)

Link between growth hormone and colorectal cancer not conclusive

A possible link between human growth hormone therapy and an increased risk of colorectal cancer is reported by researchers in this week's issue of The Lancet (2002;
360:273).

However, the researchers concede that their data do not show conclusively whether the incidence of cancer is increased by human growth hormone treatment and also stress that there is no evidence from the study as to whether there is an association between synthetic growth hormone treatment and an increased risk of cancer.

Professor Anthony Swerdlow and colleagues from the Institute of Cancer Research and Institute of Child Health, London, conducted a population study in which they measured cancer incidence and death in 1,848 people in the United Kingdom who had been treated during childhood and early adulthood with human pituitary growth hormone.

They compared the risk of cancer in the study population with that in the general population and found that patients treated with human pituitary growth hormone had raised mortality from cancer overall, colon and rectal cancer, and Hodgkin's disease.

"We found a significantly raised frequency of colon cancer mortality after growth hormone treatment which, although based on small numbers, is of concern because it concurs with raised risks found in patients with acromegaly and in individuals with previously increased concentrations of insulin growth factor-1," they say.

Among the group of patients treated with human pituitary growth hormone there were 10 cases of cancer, a number almost three times higher than expected.

The number of colon and rectal cancers expected in the study population was 0.19 and for Hodgkin's disease the expected number was 0.18. For both types of cancer the actual number seem among people treated with human pituitary growth hormone was two cases, approximately 11 times higher than expected.

The researchers conclude: "Our data do not show conclusively whether cancer incidence is increased by growth hormone treatment, but they do suggest the need for increased awareness of the possibility of cancer risks, and for surveillance of growth hormone-treated patients."

In an accompanying commentary, Dr Edward Giovannucci, Harvard School of Public Health, Boston, Massachusetts, concludes: "It must be emphasised that the treatment of growth hormone deficiency has established health benefits, and that there is no evidence that physiological growth hormone replacement increases cancer risk.

"While the data reported by Swerdlow and colleagues should not discourage appropriate treatment of growth hormone deficiency, they should provoke reassessment of the risks and benefits of growth hormone therapy for more controversial indications that are unrelated to growth hormone deficiency, particularly if such treatment is prescribed for long periods."