Managing Cancer Care and Diabetes

I was very lucky. When I was diagnosed with lung cancer nearly three years ago I was symptomatic (I had a persistent cough) but thankfully I did not have any complicating issues or disease.

I did not know at the time that the medical world uses a scoring system to quantify a patient’s general well-being. I had a “performance status” of one when I was diagnosed (symptomatic but completely ambulatory.). A performance status indicating generally good health allowed my doctors to treat me without needing to account for how treatments would affect some other disease. Today I would be scored a zero (asymptomatic, fully active and able to carry on all activities without restriction.) If I have a cancer recurrence, my general good health should help me fight the disease. These days I work hard at trying to stay healthy.

I say I was lucky, because people with cancer frequently have other medical issues, such as diabetes, high blood pressure, kidney disease, COPD, and so on. These patients are understandably more challenging for an oncologist to treat effectively.

I was surprised to learn that diabetics, despite seeing a doctor more often than most other people, appear to be less likely to be screened for cancer. That is disturbing on a number of fronts, not the least of which is the suspicion that there exists some link between cancer and diabetes. In fact, one estimate I found is that cancer rates among diabetics may be as high as 18%. The link between these two diseases is as yet unproven. Nevertheless, you would think that, given the high rate of cancer among diabetics, screening rates would be higher, not lower.

One Canadian study showed that the mammography rates for women with diabetes were more than 30% below their non-diabetic counterparts. The low screening rates in that study were attributed to “time constraints during office visits for complex disease care.” The upshot is that if you are diabetic, you may want to ask your physician about cancer screening and prevention.

Diabetic patients present treatment challenges for oncologists. For example, may diabetic patients may have pre-existing issues with their kidney or heart or suffer from neuropathy. All of theses conditions may be exacerbated by chemotherapy, depending on the agent being used. Cisplatin, which is what I was given, is known to impair the kidneys and cause peripheral neuropathy. But successful treatment typically requires that 85% of the chemo-therapeutic dose be given. Reducing the treatment dosage or timing to temper side effects may also impact the treatment’s efficacy. It is a difficult choice to have to make.

Diabetics face other challenges in being treated for cancer, with the largest being control of blood sugar levels. Treatment induced nausea and vomiting, for example, can be controlled with drugs, but steroid based anti-nausea drugs may in turn wreak havoc on controlling blood sugar levels and the amount of insulin a patient is required to take. Being able to maintain proper nutrition during cancer treatment is a challenge for a diabetic.

While the link between diabetes and cancer is not yet definitive, there are many common risk factors, including age, obesity, poor diet and lack of exercise. Prevention of diabetes is an important factor in fighting all cancers. People with diabetes double the risk of developing liver and pancreatic cancer. It is known to increase the risk for colorectal, breast and bladder cancer by 20% to 50%. In contrast, for some unknown reason, prostate cancer is less prevalent in men with diabetes. Go figure.

Research presented at ASCO this year showed that metformin, a drug commonly used in the treatment of type-2 diabetes, helped guard against tobacco-induced lung cancer in mice. More research is needed to see if this commonly used drug to treat diabetes is a potential lung cancer preventative in humans. Let’s hope research progresses soon.