The Cancer And Diabetes Connection

By Wendy Kaplan, MS, RDN, CSO, CDCES, CDN

More and more evidence shows a link between cancer and diabetes. Cancer and diabetes are frequently diagnosed within the same patient as both have overlapping risk factors that share etiologic pathways. Diabetes increases the risk for cancer, and cancer increases the risk for diabetes.

Diabetes increases the risk for hematologic cancers (leukemia, lymphoma, and myeloma). In addition, rates of stomach, liver, kidney, pancreatic, and endometrial cancers are increased in people with type 1 diabetes, whereas there is a decreased risk for breast and prostate cancers. People with prediabetes and type 2 have a twofold higher risk for cancers of the liver, pancreas, and endometrium and a 1.2-1.5 higher fold risk of colorectal, breast, and bladder. However, there is a lower risk of prostate cancer.

The link between cancer and diabetes is an important yet under-discussed area in clinical practice. Some studies suggest that even just a few days of hyperglycemia can harm the immune system. Therefore, having diabetes before a cancer diagnosis complicates cancer treatment. Additionally, some cancer treatments can induce diabetes. Some patients with treatment-induced diabetes (or steroid diabetes) may have been predisposed to the disease. However, that is not always the case.

New York Cancer & Blood Specialists continuously stay at the forefront of cancer care and addressing this need. As a Registered Dietician Nutritionist, my colleagues and I have worked tirelessly to earn the Certified Diabetes Care and Education Specialist (CDCES) board certification to better serve our patients and the multidisciplinary team.

Fortunately, due to life-saving cancer treatments, cancer survivorship has increased. However, many other health problems, including pre-diabetes and diabetes, are more prevalent with increased survivorship. Cancer survivors are at risk for multiple long-term and late-term side effects. Long-term side effects start during treatment and continue after treatment is completed. Late effects can arise months and even years after treatment.

Treatments such as antineoplastic agents, glucocorticoids, hormone-based treatments, radiation, etc., are negatively associated with diabetes and other endocrine issues. Possible mechanisms for a direct link include hyperinsulinemia, hyperglycemia, and inflammation. With hyperinsulinemia, your body overproduces insulin to compensate for higher blood glucose levels. Chemotherapy and other cancer treatments decrease your immune function. Being hyperglycemic (having extra glucose in your blood) further compounds your already immunocompromised state and paves the way for increased infections (bacterial, fungal, etc.). Inactivity, emotional stress, and extra weight (overweight or obese) are significant contributing factors to hyperglycemia. Excess weight can lead to extra insulin, extra glucose and can potentially support tumor growth.

As with many other diseases and chronic conditions, there are risk factors that are modifiable and non-modifiable. However, there are steps we can take to prevent or slow down progression. Although we cannot do anything about age and ethnicity, we can address diet, weight, physical inactivity, alcohol consumption, and smoking.

What are some things we can do? As RDNs, we partner with our patients to develop realistic healthy eating and lifestyle goals to improve clinical parameters and outcomes and help people live healthier lives. This can be very challenging, but we implement strategies to promote overall health and optimal body composition (more lean mass vs. fat mass).

Sometimes, weight gain occurs in patients during cancer treatment and post-treatment. This “extra weight” tends to be more central adiposity, or fat mass, as opposed to lean body mass, and this central adiposity is metabolically active in unfavorable ways. Unfortunately, cancer and cancer treatment can unleash various metabolic changes, including decreasing hormone levels and subsequently leading to insulin resistance, increased estrogen levels, and other factors that lead to this weight gain.

Another factor to consider is when a cancer patient does not feel well during treatment, and oral intake is suboptimal. In this situation, the “ideal healthy eating pattern” may need to be put on hold for a more liberalized diet to help meet a patient’s protein and energy needs and taste preferences. Since patients are at different disease stages during treatment may be experiencing varying nutritional impact symptoms and side effects, resulting in different food cravings, energy levels, and overall mood.

Medical Nutrition Therapy (MNT) is a necessary intervention to address this growing concern and may include but is not limited to:

• Promoting healthy food choices and diet patterns (e.g., plant-based, Mediterranean, DASH, etc.)

• Limiting refined carbohydrates
• Adjusting calorie, sugar, and fat intake
• Determining healthy ratios for macronutrients to optimize blood sugar management.
• Promoting meal consistently (consuming meals and snacks at the same time each day)
• Pairing protein with carbohydrate foods
• Educating on healthy and appropriate portion sizes.
• Encouraging physical activity and avoiding physical inactivity • Planning short brisk walks after meals
• Increasing fiber intake
• Decreasing red meat intake
• Urging smoking cessation

Although some of the above recommendations may sound vague, RDNs help set specific goals for implementation, all tailored to an individual‘s needs, medical conditions, co-morbidities, cultural preferences, etc. Multiple factors are considered in developing nutrition treatment plans, and there is no “one size fits all approach” applicable to all patients. Nutrition management needs to be individualized, and priorities (patient’s goals, risk of hypoglycemia, ability to monitor blood sugar, etc.) weighed for each patient.

Managing endocrine dysfunctions involve the entire medical team. Therefore, pharmacological intervention is typically indicated in addition to Medical Nutrition Therapy (MNT) to aid in managing hyperglycemia. Before treatment, patients with diabetes prior treatment may need a more aggressive approach for better blood sugar management. Careful attention to treatment regimes, blood glucose trends between cycles, and the addition of steroids are essential early on as they may impact management strategies.

When a patient is on steroids, blood glucose tends to be highest after lunch and dinner. All steroids increase blood sugar, with the dose being a significant factor. Knowing this will affect pharmacological and dietary interventions, perhaps with the addition of Metformin, a Sulfonylurea, insulin, or other medications. Adjusting carbohydrates at lunch and dinner meals may also be indicated. The holding of steroid medication during treatment, although uncommon, might be another approach. The multidisciplinary team will discuss and determine the best course of action.

Some research suggests the medication Metformin can lower the risk of developing cancer and possibly lead to better outcomes in those with cancer. As a result, Metformin is actively being investigated on all fronts, including its possible use as a breast cancer treatment.

The increased incidence of diabetes during and after cancer treatment underscores the need for more intense monitoring for changes in metabolic status. Glucose management improves outcomes and quality of life. Monitoring and treating are vital steps in promoting better health. Treatment providers should be on the lookout for metabolic abnormalities such as high blood sugar, elevated blood pressure, high triglycerides, low HDL cholesterol, and elevated waist circumference. Having at least 3 out of 5 of these conditions is termed “metabolic syndrome,” which can increase the risk of developing diabetes.

Research in this area is ongoing. Registered Dietitian Nutritionists are a key part of the multidisciplinary team. They promote nutritional strategies that help survivors manage co-morbidities such as diabetes, decrease the risk of cancer recurrence and promote overall better health. All these techniques and strategies to nourish the body extend well beyond the cellular level to mental health benefits.

References: Long-term diabetes risk among endometrial cancer survivors in a population-based cohort study. Gynecol Oncol. 2020 Jan;156(1):185-193. DOI: 10.1016/j.ygyno.2019.10.015. Epub 2019 Dec 12. Incident type 2 diabetes duration and cancer risk: an appropriate prospective study in two US cohorts. J Natl Cancer Inst. 2020 Sep 16;djaa141. DOI: 10.1093/jnci/djaa141. Online ahead of print. Pre-and post-diagnosis diabetes as a risk factor for all-cause and cancer-specific mortality in breast, prostate and colorectal cancer survivors: a prospective cohort study Contemp Clin Trials. 2020 May;92:105998. DOI: 10.1016/j.cct.2020.105998. Epub 2020 Apr 11. Pre-and post-diagnosis diabetes as a risk factor for all-cause and cancer-specific mortality in breast, prostate and colorectal cancer survivors: a prospective cohort study Contemp Clin Trials. 2020 May;92:105998. DOI: 10.1016/j.cct.2020.105998. Epub 2020 Apr 11. October 2020 Issue Cancer Nutrition: Metabolic Syndrome and Cancer — Insights on Their Intersection By Karen Collins, MS, RDN, CDN, FAND Today’s Dietitian Vol. 22, No. 8, P. 14 Oncology Nutrition Connection. Volume 27, Number 4, 2020; Diabetes and Cancer: Increased Risk and Mortality. Doris Piccinin, MS, RDN, CSO, CDCES, LDN Diabetes and Cancer: A Case Study Approach. Beverly Tomassian, RN, MPH, BC-ADM, CDCES, President, Diabetes Education Services 2020. How to Manage Steroid Diabetes in the Patient With Cancer. The Journal of Supportive Oncology (online). 2005.