Treating Diabetes in Cancer Patients
By Zach Bohannan
Concurrent diabetes and cancer is relatively common because of the high prevalence of both conditions. However, researchers are only beginning to understand the interactions between diabetes and cancer. “There is a growing body of research on diabetes,” said Sai-Ching “Jim” Yeung, M.D., Ph.D., an associate professor in the Department of Emergency Medicine at The University of Texas MD Anderson Cancer Center. “And now cancer researchers are beginning to integrate that knowledge into our understanding of how cancer develops and responds to treatments.”
A potentially important interaction between diabetes and cancer is the common thread of insulin signaling. Insulin is a potent promoter of cell growth and may be implicated in the development of some common cancers. Insulin-like growth factor receptors are often mutated in cancers, and the resulting dysregulation of the insulin signaling system may lead to rampant proliferation in some types of cancer.
Hyperinsulinemia, which can result from the disruption of insulin signaling or production, is a risk factor for the development and progression of several cancer types, including prostate and breast cancers. In contrast, lower insulin levels have been associated with better outcomes in diabetic patients with prostate or breast cancer.
Diabetes caused by cancer
Although many patients have diabetes long before their cancer diagnosis, it is equally as common for patients to develop diabetes because of their cancer or its treatment.
Also linked to diabetes are tumors that secrete cytokines, especially those that secrete large amounts of interleukin-6. Although the role of cytokines in insulin signaling has yet to be fully characterized, interleukin-6 and other proinflammatory cytokines can cause insulin resistance. This resistance is possibly related to increased inflammatory signaling throughout the body.
Diabetes caused by cancer treatment
The most common cause of cancer treatment–induced diabetes is glucocorticoid therapy. According to Victor Lavis, M.D., a professor in the Department of Endocrine Neoplasia and Hormonal Disorders, nearly half of the diabetic and insulin-resistant patients treated at MD Anderson are patients whose cancer treatments include glucocorticoids.
Glucocorticoids, which reduce inflammation and affect lymphocyte development, are often used as part of the treatment for hematological malignancies and some solid tumors. Glucocorticoids are also given to prevent or treat graft-versus-host disease in patients who have received allogeneic stem cell transplants for hematological malignancies (see OncoLog, April 2013). Furthermore, glucocorticoids are frequently prescribed by oncologists to control nausea or to reduce swelling in the central nervous system.
However, in addition to their beneficial effects, glucocorticoids reduce glucose clearance and disrupt the function and survival of insulin-secreting pancreatic beta cells. These disruptions to glucose metabolism cause insulin resistance and hyperglycemia and, over time, may lead to permanent diabetes.
Many cancer patients who are treated with glucocorticoids will eventually need some sort of medication for their hyperglycemia. However, Dr. Lavis said, the question of which diabetes medication would allow the best response to cancer therapy for patients with glucocorticoid-induced diabetes has yet to be explored in clinical trials.
Treating diabetic patients with cancer
Many diabetic cancer patients have poorly controlled blood sugar at the
time of their cancer diagnoses. These patients’ blood sugar must be
brought under control before they can safely undergo cancer treatment.
For more information, call Dr. Victor Lavis at 713-792-2841 or Dr. Jim Yeung at 713-745-9911.
Other articles in OncoLog, July 2013 issue: