Insulin-like Growth Factor-1 (IGF-1, Somatomedin C) Blood Levels Are Not Associated With Prostate Specific Antigen (PSA) Levels or Prostate Cancer: A Study of 749 patients.
L. Cass Terry, M.D., Ph.D., Pharm.D.,
IGF-1, also known as somatomedin C, is a polypeptide hormone about the same size as insulin. It is produced predominantly in the liver in response to growth hormone (GH) release from the pituitary gland. Many of the growth promoting effects of GH are due to its ability to release IGF1 from the liver, which in turn acts on several different tissues to enhance growth. IGF1 belongs in the superfamily of substances known as growth factors, along with epidermal, transforming, platelet derived, fibroblast, nerve, and ciliary neurotrophic growth factors. These agents have in common the ability to stimulate cell division, known as mitogenesis, and cell differentiation. Because IGF1 is mitogenic to prostate epithelial cells, as well as other cell lines in tissue culture, its role, if any, in prostate cancer has been considered and raises the question as to whether higher levels of circulating IGF1 might increase the risk of prostate cancer. The best and most sensitive screening test available for prostate cancer is prostate specific antigen (PSA), a serine protease secreted by prostate epithelial cells.
The incidence of prostate cancer increases with age in men, whereas, blood levels of IGF1 decline significantly with age, about 14% per decade after age 30. It therefore seemed unlikely that IGF1 would have any causative relationship with prostate cancer, however, it does raise the question as to whether supplementation with recombinant human GH (rhGH), as a deterrent to the aging process, might increase the risk.
The purpose of this study was to determine whether IGF1 blood levels in men receiving rhGH supplementation had any relationship to blood PSA levels, as an indicator of prostate cancer. To accomplish this goal, PSA and IGF1 levels were measured in 749 blood samples from men with ages ranging from 22 to 86 years old, many of whom were on rhGH replacement therapy. Age, IGF1, and PSA were matched in 544 individuals. Also, IGF1 levels were measured in 6 patients with known prostate cancer, prior to rhGH administration.
The mean age of all men was 55.1 + 0.5 yr. with a median of 55 and mode of 64. Mean PSA was 2.2 + 0.1 ng/ml with a median of 1.1, mode of 0.7, and range of <0 to 63.7. Trend line analysis demonstrated a clear increase in PSA levels with increasing age, as expected. Mean IGF1 was 218.8 + 3.4 ng/ml with a median of 211, mode of 183, and range of 20 to 498. There was no correlation between IGF1 and PSA levels. IGF1 levels were further broken down into quartiles and compared with PSA levels in each. This resulted in the following data:
Trend line analysis showed no correlation between IGF1 and PSA levels.
The data were then grouped by normal (<4.1 ng/ml) and abnormal (>4.0 ng/ml) PSA levels, resulting in the data below:
In this case, the mean IGF1 levels were essentially the same, even though the median PSA in the abnormal group was six times higher.
Also, the mean IGF1 level, before rhGH treatment, in 6 cases of known prostate cancer was 121.5 + 30.0 ng/ml, which places this group in the lowest quartile of IGF1 levels, regardless of age. Taken together, the data provide strong evidence that blood IGF1 levels have no relationship with PSA levels or prostate cancer. The results are in agreement with those of several other investigators (Ho, P. & Baxter, RC, Clin Endocrinol 46, 145-154, 1997; Cohen, P. et al., J Clin Endocrinol Metab 76:1031-1035, 1993; Kanety, H. et al., J Clin Endocrinol Metab 77:229-233, 1993). A recent paper (Chan, JM et al., Science 279:563-566, 1998) suggests that there is an association between circulating levels of IGF1 and prostate cancer; however, IGF1 levels were measured an average of 7 years before the diagnosis of prostate cancer and not at the time of diagnosis. Furthermore, there was no increase found in prostate cancer, or any other malignancy, in approximately 3000 patients during long term treatment with rhGH (Bengt-Ake Bengtsson, personal communication).
Conclusion: Circulating IGF1 levels have no relationship to prostate cancer and are not a risk factor in patients, with or without rhGH administration. In other words, there is no evidence that rhGH replacement to deter aging carries any increased risk for prostate cancer.
*Thanks to Dr. Ron Klatz for this "newstidbit" from his web site http://worldhealth.net
© 1998-2014 by The Hormone Shop, LLC.
This Site does not endorse any product advertised on
Disclaimer: The Hormone Shop LLC assumes no liability, whether under a theory of contract, tort, negligence, product liability or otherwise. In no event shall The Hormone Shop LLC be liable for any direct or indirect, consequential, incidental, special, punitive or exemplary damages, or for any loss incurred due to results or comments that are reported or the use of collection materials that are supplied, or any prescriptions regardless of whether The Hormone Shop LLC knew or should have known of the possibility of such damages. Furthermore, in no event shall The Hormone Shop LLC's total cumulative liability exceed The Hormone Shop LLC's net profit on any specific product, sample or consultation giving rise to the liability. The Hormone Shop LLC specifically assumes no liability incurred by any 3rd party associate and if you are reading this web site in a language other that English it has been machine translated by SYSTRAN who strives to achieve the highest possible accuracy, however no automated translation is perfect nor is it intended to replace human translators. Users should note that the quality of the source text significantly affects the translations and The Hormone Shop LLC assumes no liability for incorrect or misleading translations. The questions and comments appearing in the "Discussion Group Forum" are strictly from unknown or unidentified sources and the reader/participant should be aware that credentials from any source are completely lacking and should be questioned. The Hormone Shop LLC specifically assumes no liability for any comment or advice appearing in the "Discussion Forum".
Notice: This information on anti-aging
provided for educational and nutritional purposes. Any medical procedures,
dietary changes or the use of dietary supplements discussed herein should only
be undertaken on the advice of a qualified medical doctor. Although listed and
sold as dietary supplements these are not innocuous, inert substances; rather they can and
do affect vital systems within the human body and it is for this reason that you
are urged to find a medical doctor who will work with you in monitoring and
maintaining your well being.