Extramedullary dissemination of multiple myeloma portends more aggressive disease but no predictive circulating biomarkers for this condition are yet available and the molecular mechanisms involved in extramedullary progression are still being learned. New research suggests that chemotherapy stress-induced long noncoding MALAT1 RNA might be one such culprit.

Extramedullary multiple myeloma is the clonal plasma cell spread to tissues outside of bone marrow; it is present at the time of diagnosis in 7% to 20% of patients and occurs with disease progression and relapse.1 Cancer cells are suspected to spread to new tissues and organs via the blood following cortical bone destruction or fracturing, but little has been known until recently about the underlying molecular mechanisms.1

“Extramedullary myeloma often arises as a consequence of genetic progression events, as are seen with more advanced disease,” noted Rafael Fonseca, MD, Getz Family Professor of Cancer and chair of the department of medicine at the Mayo Clinic in Phoenix, Arizona, and chair of the American Society of Hematology (ASH) Committee on Plasma Cell Neoplasia. “For instance, it is common for patients who have extramedullary myeloma to have deletions of 17p13 at the site of p53. Mutations of p53 are also common. It is also more common for patients who have high-risk cytogenetic markers such as t(14;16) to have extramedullary disease.”

“When myeloma cells can reside out of the bone marrow microenvironment, it usually means that they have become ‘emancipated,’ and mostly through genetic progression,” Dr Fonseca added.

Extramedullary disease rarely occurs in isolation. 

“Is not uncommon for patients to have other features of advancing myeloma including renal failure or hypercalcemia,” Dr Fonseca explained. “Most patients that present with extramedullary disease will need aggressive treatment.”

Extramedullary disease is increasingly encountered in the clinic, noted Ola Landgren, MD, PhD, chief of myeloma service and professor of medicine at Memorial Sloan Kettering Cancer Center in New York, New York.

“That is driven by 2 major factors,” he told Cancer Therapy Advisor. “First, access to better myeloma drugs which keep patients alive longer with the possibility to eventually develop extramedullary disease, which is more likely in later relapses. Second, more sensitive methods to detect extramedullary disease (such as PET/CT and/or MRI).”

Newer therapies are changing the natural history of multiple myeloma, allowing more patients to live longer, agreed Dr Fonseca. “In the past, we did not see much in the form of extramedullary disease but only in those very aggressive cases,” he explained. “Now we can see cases of pleural effusions, central nervous system disease, and even very unusual clinical presentation such as hepatic masses.”

Physicians need to be aware that these can be confused with other tumors, Dr Fonseca said. “These clinical presentations are atypical for what we normally think about multiple myeloma.”

Because extramedullary myeloma is an indicator of more aggressive disease, more intensive treatment, including combination chemotherapy, is frequently prescribed.