In this month’s March issue of JAMA (the Journal of the American Medical Association), an interesting article appeared entitled “The Surprisingly Positive Association Between Obesity and Cancer Immunotherapy Efficacy.” The article summarized recent findings that modern immune-system based anti-cancer medications sometimes work better if a patient is obese. This seems to be true in the case of melanoma in males. Obese men with melanoma exhibited increased survival on immunotherapies than non-obese men. This was not true for traditional chemotherapy.
Before we get ahead of ourselves and encourage the men in our lives to eat more and exercise less, it’s worth mentioning that other studies have found that obesity increases our risk of developing cancers in the first place. This is also true for melanoma – in one study, obese men were 31% more likely to develop melanoma than non-obese men. The aforementioned article simply supports that obese men with a melanoma diagnosis on certain medicines may fare better than fit males with a melanoma diagnosis.
To a physician, the finding of a positive effect of obesity in cancer is even more surprising because obesity is generally thought of as an immunocompromised state. In general, obesity weakens the immune system. Why would a medicine that depends on the immune system work better in someone with an unhealthy immune system?
Perhaps the medicine does not so much depend on the immune system to work as bolster the immune system. If a lack of a healthy immune system is part of the obese patient’s problem, then should we not have anticipated that the obese patient would experience greater benefit from an immune-bolstering therapy?
Biology is very difficult to predict one or two steps ahead. It is easy to formulate a hypothesis for why an immune-based therapy would be more effective in someone with a compromised immune system, just as it is easy to formulate a hypothesis for why such a medicine might be less effective. Perhaps immunocompromise means immune-based therapies can’t exert their maximum effect. Or perhaps immunocompromise means immune-based therapies are even better than anticipated because they are meeting a greater need.
Regarding the melanoma case, why would obesity be helpful in men and not women for certain cancers? Women deposit fat differently; fat in different locations can produce different hormones and be more or less pro-inflammatory, and perhaps women were designed to be able to be healthy with higher levels of adipose tissue, but what is the key factor? Biology is very difficult to predict by first principles alone.
That is why a familiarity with the medical literature, a willingness to study, and a reliance on experimental results are so critical to a physician’s efficacy. All this is what is meant by the buzz phrase “evidence based medicine.”
And as surprising as it may be that obesity may offer a rare health benefit, you might be interested to find that several “unhealthy” things may result in various benefits. If you’re curious, then look into the evidence that tobacco use may lower the risk of Parkinson disease, ulcerative colitis and be associated with lower risk of obesity… almost everything carries risk and reward. Many times, a physician’s job is to help you balance risk and reward: Is it really important that you spend less time in the sun? Should you have this surgery? These are all risk and reward questions that can be answered with the help of a (or several) qualified physicians.
Dr. Brent Taylor is board certified in dermatology, certified by the American Board of Venous and Lymphatic Medicine, and is fellowship-trained in Mohs micrographic surgery, cutaneous oncology and the treatment of varicose veins and venous disorders. If you or a loved one has a history of skin cancer, a suspicious spot, a vein issue or other dermatologic need, consider making an appointment at Premier Dermatology and Mohs Surgery of Atlanta today.
At Premier Dermatology and Mohs Surgery of Atlanta, it is our pleasure to meet your skin care needs. Board certified and fellowship-trained, Dr. Brent Taylor is a skin cancer, vein and aesthetic expert honored to be of service.