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Blood Disorder MGUS Precedes Most Cases Of Multiple Myeloma

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Published: Mar 4, 2009 7:18 pm

Researchers recently announced that the blood disorder monoclonal gammopathy of undetermined significance (MGUS) precedes the vast majority of multiple myeloma diagnoses. Until now, researchers had disagreed whether MGUS was a consistent precursor to full-blown myeloma disease.

Study authors examined blood samples from 71 people who developed multiple myeloma while enrolled in the National Cancer Institute's Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial.

Since its inception in 1992, the trial had collected frequent blood samples from participants, making it an invaluable resource for investigating early cancer markers. Although the trial did not aim to investigate multiple myeloma specifically, its database contained the 71 multiple myeloma patients' blood samples from years before they became sick.

In analyzing these samples, researchers discovered that almost every patient's blood showed evidence of preceding MGUS. In some cases it appeared as early as a decade before the multiple myeloma diagnosis. While the vast majority of MGUS cases do not progress to multiple myeloma, these findings confirm what many physicians, like Dr. Robert A. Kyle of the Mayo Clinic, have long suspected, "MGUS is a precursor lesion of multiple myeloma, and that all patients with [multiple myeloma] have a preceding MGUS or smoldering myeloma."

MGUS is an asymptomatic blood disorder characterized by an abnormally elevated level of monoclonal protein, often discovered incidentally during testing for other disorders. Monoclonal proteins, or "M-proteins," are produced by plasma cells in the bone marrow. The presence of M-protein in the blood indicates that these plasma cells are proliferating excessively, similar to what occurs in multiple myeloma. Unlike full-blown cancer, even elevated M-protein levels remain relatively low in MGUS, and the disorder causes no symptoms.

Three percent of Americans over age 50 possess MGUS, and reports suggest that the condition occurs more frequently in people of African descent.

While this study confirms that MGUS precedes virtually all multiple myelomas, researchers caution that most incidences of MGUS will never advance to clinical disease; given that only one percent of MGUS cases progress to multiple myeloma each year and that the disorder causes no ill effects, MGUS does not presently warrant treatment. "We now have a window of time for studying how multiple myeloma begins and progresses," explains lead study author Dr. Ola Landgren of the National Cancer Institute.

Past studies have already identified some risk factors for MGUS progression to multiple myeloma, including a high serum M-protein level. Further studies will hopefully clarify and identify further risk factors, as well as discover potential avenues for preventing MGUS progression. According to Kyle, multiple myeloma could essentially be wiped out if we could figure out how to treat MGUS.

For more information, see the National Cancer Institute News Bulletin and the full study in Blood Journal. Further information can be found in a recent Myeloma Beacon article about the effect of radiation exposure on MGUS progression.

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  • mary ward said:

    I found out I had MGUS after a blood test. I was trying to donate a kidney to my husband and it was all a go, but after my second 24 hour creatinine clearance came back with high protein traces I was denied, so my doc did some test and then sent me to a hematologist and they said I had high protein levels in my blood. Also the urologist from the transplant team said if they were to take my kidney to donate, that I may be his patient down the road.

    So is the protein in my urine and my blood high in protein because of the MGUS? Is there a cure, and why won't they let me donate my kidney to save my husband's life? If MGUS is harmless, why won't they let me donate, and is the high protein in my urine related to MGUS?

    - Frustrated in Florida, what can I do, any suggestions?

  • Myeloma Beacon Staff said:

    Dear Mary,

    Dr. Ola Landgren, an MGUS specialist at National Cancer Institute, NIH, in Bethesda, Maryland, said the following:

    This is a complicated question as it covers several aspects. Based on the information you provide, here is my answer: I don’t think a diagnosis of MGUS is the problem per se. Based on current knowledge, there is no evidence that MGUS or myeloma would spread to the recipient if a person with MGUS donated a kidney to another person.

    However, you are also saying that your kidneys leak (high levels of?) proteins, which, in that case, indicates that the kidney function is not optimal.

    For any person who wants to donate a kidney, and the kidney function is insufficient, there are things to consider. The recipient may not benefit from a insufficient kidney. In such a scenario, another donor is the preferable way to go. Also, a potential donor with poor kidney function runs the risk of needing a transplant him/herself in the future (due to only one kidney left, and that kidney is not working well).

    In most cases, MGUS patients have normal kidney function and there should not be a problem being a donor. Your kidney doctor and the kidney transplant doctor should be able to provide you with detailed information regarding the degree and type of kidney failure you have, and the potential need for additional work-up and follow-up.

    I hope this is useful.

    Dr. Landgren, National Cancer Institute, NIH, Bethesda, Maryland