Self-Evaluation: Multiple Myeloma and Plasma Cell Dyscrasias- MGUS

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TRANSCRIPT Welcome to the Self-Evaluation episode of the ASCO University weekly podcast. My name is Dr. Karen Winkfield, and I am Associate Director for Cancer Health Equity and Director of Hematologic Radiation Oncology at the Comprehensive Cancer Center at Wake Forest Baptist Health in Winston-Salem North Carolina.

Today, we feature a self-evaluation question on the treatment of multiple myeloma and other plasma cell dyscrasias, and we begin by reading the question stem.

A 65-year-old woman was found to have free light-chains in her urine after she presented with proteinuria. A 24-hour urine collection contained 0.6 grams of monoclonal lambda light-chains, and the urinary sediment was normal.

She had normal complete blood count, renal function, and serum lactate dehydrogenase and calcium levels. Serum protein electrophoresis was normal with no monoclonal component. Subsequent free light-chain, or FLC, studies revealed kappa at 68.5 milligram per liter and lambda at 16.7 milligram per liter with FLC ratio of 4.1 with a normal range of 0.26 to 1.65.

The bone marrow aspirate revealed 6% of mature-looking plasma cells. Bone marrow biopsies failed to demonstrate any amyloid deposits. Both conventional and fluorescent in situ hybridization cytogenetic analyses were normal. Skeletal X-rays, as well as spinal access MRIs were normal.

The diagnosis is light-chain monoclonal gammopathy of undetermined significance, or LC MGUS. Which of the following is an accurate description of this disease? A, around 30% of cases present with kidney disease. B, around 3/10 of 1% per year of cases progress to light-chain multiple myeloma. C, around 30% of all MGUS is comprised of this condition. D, around 3% of the general population older than 50 years has this condition.

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The correct answer to this question is B, around 3/10 of 1% per year of cases progress to light-chain multiple myeloma. This answer reflects the natural history of LC MGUS.

Briefly, the other choices presented in this question are incorrect for the following reasons. Approximately 23% of LC MGUS cases have or will develop renal disease. Therefore, answer A slightly overstates the incidence at 30%.

Similarly, LC MGUS comprises only 19% of total cases of MGUS. This is consistent with the proportion of light-chain multiple myeloma cases among newly-diagnosed multiple myeloma patients. An estimated 0.8% of the general population age 50 years and older has LC MGUS.

Thank you for listening to this week's episode of the ASCO University weekly podcast. For more information on the treatment of multiple myeloma and other plasma cell dyscrasias, visit the comprehensive E-Learning Center at university.asco.org.

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The purpose of this podcast is to educate and to inform. This is not a substitute for professional medical care and is not intended for use in the diagnosis or treatment of individual conditions. Guests on this podcast express their own opinions, experience, and conclusions. The mention of any product, service, organization, activity, or therapy should not be construed as an ASCO endorsement.