High BMI may increase spread of blood cancer: study

Obesity is seen as a cause for many cancers, with each 5 kg per metre square rise in BMI linked to a 10% increase in cancer-related deaths

Researchers have found that as body mass index (BMI) increases, so does the growth and spread of the blood cancer, multiple myeloma.

"Once a person with cancer is out of the normal weight category, their BMI is contributing to multiple myeloma growth and progression," said Katie DeCicco-Skinner from American University.

Researchers examined BMI of normal, overweight, obese and morbidly obese patients, and the effects on multiple myeloma.

Obesity is believed to be a risk factor for many cancers, and each 5 kilogramme per metre square increase in BMI is associated with an increase of 10 per cent in cancer-related deaths, studies show.
 
In the multiple myeloma study, normal weight was defined as a BMI of no more than 25 kilogrammes per square metre, and morbidly obese was in the range of 35 to 40 kilogrammes per square metre.

Researchers obtained stem cells from the discarded fat of liposuction patients who underwent elective surgery. They turned them into fat cells and cultured the fat cells with multiple myeloma.

In bone marrow, where multiple myeloma often takes root, fat cells play an important role in the proliferation, survival, progression and drug resistance of the cancer cells.

As a patient's BMI increases, fat cells communicate with multiple myeloma cells, researchers found. Fat cells grow larger, gain additional lipid and secrete proteins linked to cancer.

Researchers also found a correlation between BMI and angiogenesis and adhesion, key indicators of progression.

"We know multiple myeloma cells will anchor into bone marrow, and fat cells in the bone marrow will support the growth and spread of the cancer," said DeCicco-Skinner.

"In our study, as BMI increased, we started seeing an increase in the ability of multiple myeloma cells to adhere, which causes the cancer to better anchor," DeCicco-Skinner said.

"With angiogenesis, cancer cells cannot exist without their own blood supply. We also found the amount of blood vessels that developed was directly proportional to a patient's BMI," she added.

Researchers assumed cancer proliferation would benefit from higher-than-normal BMI because of the epidemiological link between obesity and cancer. But the relationship between multiple myeloma and the BMI of obese and morbidly obese patients was drastic, researchers said.

"We found that fat cells from obese or morbidly obese patients secreted a high amount of inflammatory proteins, which contributed to tumour progression," said DeCicco-Skinner.

The findings suggest a new approach for the treatment of multiple myeloma. Physicians may want to consider tailoring drugs based on a patient's BMI because a drug may not be as effective in obese or morbidly obese patients, researchers said.

The study was published in the journal Cancer Letters.