Of greater concern is the fact that milk from rBGH-treated cows has higher levels of IGF-1, a hormone that normally helps some types of cells to grow. Several studies have found that IGF-1 levels at the high end of the normal range may influence the development of certain tumors. Some early studies found a relationship between blood levels of IGF-1 and the development of prostate , breast , colorectal , and other cancers, but later studies have failed to confirm these reports or have found weaker relationships. While there may be a link between IGF-1 blood levels and cancer, the exact nature of this link remains unclear.
Abnormal GH levels can usually be modified once the causes are identified. Synthetic GH is available to alleviate deficiencies in children (treatment of adults with GHD is more controversial). Combinations of surgery, medication, and radiation can be used to treat pituitary tumors that are causing excess GH production. The important thing is to identify GH abnormalities as soon as possible for good outcomes. If left untreated, a child with GH deficiency will continue to have a short stature compared to peers. Likewise, the bone growth changes associated with gigantism and acromegaly are permanent.