A new prognostic model for PTCL?

SAN FRANCISCO—Unlike its predecessors, a new prognostic model suggests race and histology are important predictors of outcome in patients with peripheral T-cell lymphoma (PTCL).

Researchers analyzed nearly 9000 patients diagnosed with PTCL in the US and found evidence to suggest that patient age and race, as well as histology and disease stage can be used to predict overall survival (OS).

The group’s findings also suggested the use of radiation is associated with improved OS. And later diagnosis may be associated with favorable outcome.

Adam M. Petrich, MD, of Northwestern University in Chicago, presented this research at the 6th Annual T-cell Lymphoma Forum, which took place January 23-25. Dr Petrich was 1 of 2 speakers to receive a Young Investigator Award for his presentation.

Dr Petrich noted that at least 5 models have been used to predict outcomes in patients with newly diagnosed PTCL—the International Prognostic Index (IPI), the Prognostic Index for PTCL (PIT), the International PTCL Project model (IPTCLP), the modified Prognostic Index for T-cell Lymphoma (mPIT), and the Extranodal Natural Killer/T Cell Lymphoma (ENKTL) model.

But these models have limitations, including small patient numbers and issues with applicability. So Dr Petrich and his colleagues wanted to take a closer look at prognostic factors in PTCL, to determine which factors from previously published models remain relevant.

Patient characteristics

The researchers used data from the SEER database, which included 20 state and local registries and captured 28% of the US population. There were 8802 cases of PTCL diagnosed between 2000 and 2010.

Patients ranged in age from 20 to 85 years, and 59% were male. With regard to race, 77% of patients were white, 13% were black, 9% were classified as “other,” and 1% were of unknown race.

Forty-eight percent of patients had stage I-II disease, 31% had stage III-IV, and the stage was unknown for 21% of patients. Extranodal disease was absent in 60% of patients, present in 26%, and unknown in 14%.

Histologies were as follows:

• 38.1% of patients had PTCL-not otherwise specified (PTCL-NOS)
• 24.2% had anaplastic large-cell lymphoma (ALCL)
• 12.7% had angioimmunoblastic T-cell lymphoma (AITL)
• 9.3% had adult T-cell leukemia/lymphoma (ATLL)
• 6.9% had extranodal NK/T-cell lymphoma (ENKTL)
• 3.2% had T-cell-prolymphocytic leukemia(T-PLL)
• 2.5% had T-cell large granular lymphocytic leukemia (T-LGL)
• 1.2% had subcutaneous panniculitis-like T-cell lymphoma (SCPTCL)
• 1.1% had enteropathy-associated T-cell lymphoma (EATL)
• 0.6% had hepatosplenic T-cell lymphoma (HSTL).

Prognostic factors revealed

The researchers performed univariate and multivariate analyses to determine the importance of the aforementioned factors on OS.

“We decided, since we have a large number of patients, to use a very stringent P value,” Dr Petrich said. “Only those that are less than 0.0001 were considered significant.”

In univariate analysis, age, race, disease stage, extranodal disease, use of radiation, and histology all significantly impacted OS. But in multivariate analysis, only race, age, histology, and disease stage retained significance.

“Extranodal disease is associated with protection from overall survival, but that P value did not reach significance (P=0.009),” Dr Petrich said.

Likewise, patients diagnosed from 2009 to 2010 had better OS than patients diagnosed from 2000 to 2008, but this did not meet the significance criterion (P=0.0002).

On the other hand, OS was significantly worse for black patients compared to white patients. And compared to patients aged 20-24, those 55 years of age and older had a significantly increased risk of death.

Compared to patients with PTCL-NOS, those with EATL, ENKTL, and T-LGL all had significantly worse OS. And patients with advanced-stage disease had significantly worse OS.

The researchers also looked at the use of radiation and found that it had a significant impact on survival.