Multiple Myeloma

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What is multiple myeloma?

Multiple myeloma is often referred to simply as myeloma. It is a type of cancer that starts in the plasma cells of the bone marrow. These are protein-making cells which normally make all of the different kinds of proteins that comprise the antibodies of the immune system. In multiple myeloma, the plasma cells undergo what is referred to as a malignant transformation and thereby become cancerous. These myeloma cells stop making different forms of protein in response to the immune system's needs and instead start to produce a single abnormal type of protein referred to as a monoclonal or M protein. Multiple myeloma plasma cell populations accumulate and these collections of cells called plasmacytomas can erode the hard outer shell or cortex of the bone that normally surrounds the marrow. These weakened bones show thinning of the bone such as is seen in nonmalignant osteoporosis or what appear to be punched out or lytic bone lesions. These lesions may cause pain and even breaks or fractures of the bones so damaged. They may cause other systemic problems listed below.

What causes multiple myeloma?

What triggers plasma cells to become malignant in multiple myeloma is not known. The cancerous myeloma plasma cells proliferate and crowd out normal plasma cells and can etch away areas of bones. The proteins produced in large amounts can cause many of the symptoms of the disease by making the blood more thickened (viscous) and depositing the proteins in organs that can interfere with the functions of the kidneys, nerves, and immune system.

What are risk factors for multiple myeloma?

The definitive cause of multiple myeloma has not been established, but research has suggested several factors may be risk factors or contribute to multiple myeloma development in an individual. A genetic abnormality such as c-myc oncogenes and others have been associated with multiple myeloma development. Currently, there is no evidence that heredity plays a role in multiple myeloma development. Environmental exposures to herbicides, insecticides, benzene, hair dyes, and radiation have been suggested as causes but definitive data is lacking. Inflammation and infection have been suggested but again not proven to cause multiple myeloma. However, a benign proliferation of a plasma cell can result in a situation where a monoclonal antibody is produced in high amounts (but not as high as seen with multiple myeloma). This result is termed monoclonal gammopathy of unknown or undetermined significance (abbreviated as MGUS). About 19% of MGUS patients develop multiple myeloma in about two to 19 years after MGUS diagnosis.

Medically Reviewed by a Doctor on 2/26/2015

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Could weight gain increase your risk for multiple myeloma?

Weight Gain & Cancer Risk

Medical Author: Melissa Conrad Stöppler, MD
Medical Editor: William C. Shiel Jr., MD, FACP, FACR

Excess weight is a known risk factor for many chronic diseases, such as diabetesand heart disease. Obesityhas also been linked an increased risk for developing some cancers. To clarify the effects of weight gain on cancer risk, researchers in 2007 conducted an analysis of many studies reported in medical journals that describe 282,137 cases of cancer. The researchers wanted to see if weight gain had an effect on the risk for certain cancer types.

In particular, the researchers looked at the risk of cancer associated with a weight gain corresponding to an increase of 5 kg/m2 in body mass index(BMI). In terms of actual pounds gained, a man with a normal-range BMI of 23 would need to gain 15 kg (33 lbs.) of weight, while a woman with a BMI of 23 would need to gain 13 kg (28.6 lbs.) to correspond to an increase of 5 in the BMI.

The results, published in the Lancet in February 2008, revealed that weight gain is positively associated with the risk of developing a variety of types of cancer as described below.

For women, a weight gain corresponding to an increase of 5 in the BMI resulted in a significant increase in risk for developing four cancer types:

  • esophageal adenocarcinoma(double the risk),
  • endometrial cancer (slightly more than double the risk),
  • gallbladder cancer (slightly more than double the risk), and
  • kidney (renal) cancer.

In women, a weaker but still positive increase in cancer risk with weight gain was demonstrated for the following cancer types:

  • postmenopausal breast cancer,
  • pancreatic cancer,
  • thyroid cancer,
  • colon cancer,
  • leukemia,
  • multiple myeloma, and
  • non-Hodgkin's lymphoma.