Human Growth Hormone (HGH), also known as somatotropin, is a naturally occurring peptide hormone synthesized and released by the pituitary gland.
HGH and Its Role in the Body
HGH plays a multifaceted role. It promotes the growth of bone and cartilage, especially during puberty, contributing to increased height. After the growth plates in bones fuse, HGH continues to maintain normal body structure throughout life.
Beyond its role in physical growth, HGH significantly impacts metabolism. HGH increases the production of Insulin-like Growth Factor 1 (IGF-1), a hormone that helps regulate blood sugar levels and influences the metabolism of fats, muscles, and tissues. HGH also contributes to cellular repair and regeneration across various tissues, including muscle, bone, and skin. Its levels naturally fluctuate throughout the day, influenced by physical activity, sleep, and nutrition, with peak production occurring during sleep.
Does HGH Increase Cancer Risk?
Whether HGH supplementation or elevated natural levels increase the risk of developing new cancers in healthy individuals is a complex area of ongoing research. Some research suggests a potential association between elevated circulating IGF-1 levels, which are mediated by HGH, and an increased risk of certain cancers, such as breast, colorectal, and prostate cancers.
However, many studies do not definitively establish a direct causal link between HGH treatment and the development of new cancers in individuals without prior risk factors. For instance, a meta-analysis of over 11,000 participants found that growth hormone replacement therapy in adults with growth hormone deficiency was associated with a decreased risk of cancer. Large cohort studies in children treated with recombinant HGH for growth failure have generally not shown a clear increased risk of new primary cancers.
Despite these findings, some studies report specific concerns. A long-term study of patients treated with human pituitary GH in childhood showed an increased risk of colorectal cancer and Hodgkin lymphoma, though the absolute number of cases was small. Some analyses also indicate a raised incidence of bone and bladder cancers in certain groups of HGH-treated patients without a prior cancer diagnosis. These findings highlight the need for continued, long-term surveillance and further investigation.
HGH and Existing Cancer Growth
A distinct concern is whether HGH can accelerate the growth or progression of cancers that are already present, even if undiagnosed or in remission. The biological mechanisms by which HGH, primarily through its mediator IGF-1, could promote cancer growth are well-understood. IGF-1 stimulates cell growth and proliferation and inhibits apoptosis, the programmed death of cells. This anti-apoptotic effect could allow abnormal cells to survive and multiply, potentially aiding cancer progression.
HGH receptors are often overexpressed in various cancer types. Autocrine or paracrine HGH, meaning HGH produced within the tumor or by nearby cells, can contribute to cancer promotion. Studies show that HGH can enhance the proliferation, survival, migration, and invasion of breast cancer cells and promote chemoresistance. It can also suppress pro-apoptotic proteins in cancer cells, allowing them to evade cell death induced by therapies like chemotherapy or radiation.
This suggests that while HGH may not directly cause cancer, its presence and activated signaling pathways, particularly through IGF-1, can create an environment conducive to the survival and proliferation of existing cancerous cells. For individuals with a history of cancer, or those undergoing cancer treatment, HGH’s potential to promote tumor growth or recurrence is a significant consideration. The implications extend to various cancer types, including colon, thyroid, gastric, breast, and urinary tract cancers, where links to elevated GH and IGF-1 levels have been explored.
Key Considerations for HGH Use
Given current scientific understanding, individuals considering HGH therapy should engage in thorough discussions with healthcare professionals. This is important for those with a personal or family history of cancer. The benefits of HGH replacement therapy in cases of diagnosed deficiency must be carefully weighed against any observed risks related to cancer.
While current evidence does not consistently support a direct association between HGH replacement therapy and primary tumor recurrence or increased cancer mortality in childhood cancer survivors, long-term safety data remain limited. A cautious approach is advised. Healthcare providers will assess individual risk factors, including previous cancer type, prior treatments like radiation, and genetic predispositions to malignancy. Regular follow-ups and monitoring for cancer are recommended for those receiving HGH treatment.