Certain chromosomal abnormalities are linked to reduced survival rates in some multiple myeloma patients, states an article in the January edition of Leukemia.

The Mayo Clinic developed a risk stratification model based on this information, which examines high-risk chromosomal characteristics and the percentage of newly diagnosed myeloma patients who display each characteristic.

Patients with a deleted chromosome 13 (seen in 14 percent of newly diagnosed patients) show a significantly reduced rate of survival, with some studies providing a median survival time of fifteen months.

Those who exhibit hypodiploidy, or a chromosome number less than the normal 46 seen in humans, also show a significantly reduced survival rate. Hypodiploidy which does not include a deletion of chromosome 13 is seen in 9 percent of diagnosed patients, while hypodiploidy including a deletion of chromosome 13 is seen in 17 percent.

Poor prognosis may be seen in patients with chromosomal translocations, as well. Translocations involve the exchange of genetic material between two unrelated chromosomes.

One clinical study done by the Eastern Cooperative Oncology Group linked certain translocations to poor prognosis in myeloma patients, with a median survival time of 25 months. Translocations between chromosomes 4 and 14 occurred in 15 percent of newly diagnosed patients. Translocations between chromosomes 14 and 16 happened in 5 percent.

The Mayo Clinic’s model notes that patients with elevated plasma cell labeling indexes, which measure tumor aggressiveness, also show poor prognosis. This characteristic is seen in 6 percent of newly diagnosed myeloma patients.

Overall, 25 to 30 percent of all myeloma patients show one of the aforementioned high-risk abnormalities.

These abnormalities are distinguished in part by conventional cytogenetic methods, which involve preparing cells in a state where chromosomes are easily visible and then banding them to recognize irregularities.

Abnormalities are also detected by newer methods, such as fluorescent in situ hybridization (FISH) and gene expression profiling. FISH uses fluorescent-labeled probes to showcase anomalies, and gene expression profiling can monitor gene activity to determine how cells react to particular treatments.

The authors of the article recommend that FISH, conventional cytogenetics, or preferably both should be done at the time of diagnosis. They say that gene expression profiling is also useful in risk stratification, but is not yet widely available.

Though using these risk factors to modify therapeutic techniques may become an option one day, the article states that this idea is controversial and requires further study.

For more information on risk stratification in multiple myeloma, see the full article in the journal Leukemia ^[1]. Also, see the previous Beacon articles in this series on diagnostic criteria ^[2] and staging ^[3], and the Beacon article on risk stratification ^[4] discussion at the XII International Myeloma Workshop. A future installment detailing new information on response criteria will follow.