Cancer Immunotherapy

How Obesity Causes Some Cancers

Obesity can cause cancers. But how does this work? And is obesity getting in the way of reducing deaths from cancer? New research sheds light on these questions. It points to the role of immune function in both diseases. It also offers clues for the path to better solutions.

Myeloid Cells and Immune Function

Much of the research on obesity and cancer focuses on the role of chronic inflammation. The low-grade, chronic inflammation of obesity is at the heart of the problem. It sets up conditions that favor cancer cells. But inflammation is just the start. A new review in Obesity tells us that the key actors in this process may be myeloid cells that actually suppress immune function. Maria Dulfary Sanchez-Pino and colleagues tell us that these cells do this in response to obesity and inflammation.

The inflammation is the start of this process. Then myeloid cells take it from there. The way that they alter normal immune function sets the stage for cancer cells to take hold. This is an adaptive form of immunity that’s unhelpful. Immune cells are adapting to obesity in a way that makes the body vulnerable to certain cancers.

Ironically, in some cases the immune response to obesity can help with the response to immune therapy for cancer. But this is not exactly a consolation prize. Obviously, it’s best not to be dealing with cancer. It does, however, provide more clues to the immune dysfunction going on between obesity and cancer. This may lead to better therapies, says Sanchez-Pino.

An Effect on Cancer Deaths?

In JAMA Open Networks, Christy Avery, Annie Howard, and Hazel Nichols take a hard look at trends in obesity-related cancers. This is a list of 13 cancers in which obesity clearly has a role.

Based on data from 50 million people, the researchers found a big difference in trends for deaths from cancers linked to obesity compared to all others. For cancers not linked to obesity, deaths are going down three times as fast. Nichols says this points to the need for more effective responses to obesity:

“These are cancers where we could see even larger mortality improvements with creative and practical tools to combat obesity.”

Clearly, denying people access to obesity care is taking a toll on health. It shows up in the cancers that result from untreated obesity.

Click here for the Sanchez-Pino study and here for the study by Avery et al. For further perspective, click here and here.

Cancer Immunotherapy, scanning electron micrograph by Rita Elena Serda via the NIH Image Gallery / flickr

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June 9, 2021

3 Responses to “How Obesity Causes Some Cancers”

  1. June 09, 2021 at 11:10 am, David Brown said:

    I fail to see how obesity causes anything. It’s a symptom; an indication that a person is either overeating or consuming a diet that is metabolically disruptive..

    In the former case, the excess fat is subcutaneous and is mostly saturated.

    In the latter case, much of the excess fat is ectopic.

    • June 10, 2021 at 4:52 am, Ted said:

      The suggestion that obesity is merely a symptom of something else reflects a misunderstanding of what obesity is. A high BMI is a symptom, but obesity is a disease of excess or abnormal adiposity that harms health.

      Apart from that, David, I was surprised that you did not read the Sanchez-Pino paper and note the reference to a role for linoleic acid in this pathology.

  2. June 11, 2021 at 12:45 am, David Brown said:

    Good point, Ted. I should have read the Sanchez-Pino paper. On page 949 it says, “Hyperplastic and hypertrophic adipocytes provide a continuous source of lipid species, including SFAs, which propagate the proinflammatory condition of obesity.

    Typically, researchers doing murine obesity experiments use lard as a fat source to induce obesity. Lard derived from CAFO pigs contains excessive amounts of linoleic acid as compared to pastured animals. Annadie Krygsman explains why this can make the interpretation of results problematic.