Multiple myeloma (MM) is a cancer of the white blood cells, specifically the plasma cells that are important in making antibodies. It is a relatively rare cancer affecting approximately 0.7% of people in their lifetime. MM has a 48.5% survival rate after 5 years but the cancer itself is considered incurable, however treatable. MM cells tend to accumulate in the bone marrow where they interfere with the production of normal blood cells. There is a strong relationship between obesity and the risk of MM. For every 5 point increase in BMI (a ratio of your height to your weight) there is an 11% increase in your risk for developing MM. Normal BMI ranges from 18.5-25 while obesity begins around 30-35 and morbid obesity is from 35-40. While we know that obesity is a risk factor for MM, and may other cancers, we do not fully understand the mechanism by which obesity increases our risk for cancer. To answer this question, a group of researchers from Washington D.C. investigated how fat cells taken during liposuction affect cancer cells ability to grow and spread.
The tissue taken during liposuction was filtered to get out only the fat or adipose stem cells (cells that can turn into mature adipose cells). These stem cells were matured and then split into four groups based upon the patient’s BMI. These groups were: healthy (BMI 20-25), overweight (BMI 25-30), obese (BMI 30-35), and morbidly obese (BMI 35-40). The researchers then put these mature fat cells with MM cancer cells and monitored how fast the cancer cells grew and how well they stuck to the dishes (a measure of their ability to spread). They also measured how well the mature fat cells could stimulate the formation of new blood vessels (angiogenesis), a key feature of cancers. When the researchers put fat cells from obese people with MM cancer cells, the cancer cells survived better than if they were with fat cells from healthy people. The cells from obese people also promoted the cancer cells to adhere to their surroundings better and were also able to stimulate the formation of new blood vessels. Each of the results was even more true for the cells from the morbidly obese population. This indicates that a signal released by the adipocytes is promoting cancer cell survival and movement.
This study provides evidence for how obesity can influence someone’s risk for developing cancer. The increased survival of the MM cells in the presence of an obese person’s fat cells promotes the development of cancer and also makes it harder for chemotherapeutics to treat and kill cancer cells. This means doctors may need to alter treatment regiments to block this pro-survival signal so that they can properly target the cancer. Additionally, cancer cells need food and energy, they do this my making their own blood vessels to supply them with their energy needs. The ability of fat cells from obese individuals to promote blood vessel growth essentially primes the body for the development and growth of cancer cells into tumors. This result is only currently applicable to multiple myeloma but the same result could hold true for many different types of cancer. There are great treatment potentials here but some questions remain. How does weight loss affect this result? If a person who was obese lost weight to get to a healthy BMI does this now reverse the effect of their fat cells on cancer cells? Or is the damage done, once a obese fat cell always an obese fat cell?
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