Tumor Size After Chemo Improves Predictive Value of PET Scans in Hodgkin's

A new study finds that relative tumor size improves the predictive value of PET scans in patients with advanced-stage Hodgkin's lymphoma.

This study was a prospective cohort study of 739 adults with advanced-stage Hodgkin’s lymphoma who had least one nodal site measuring 2.5 cm or more after chemotherapy.

The main finding from this study is that patients with less than 40 percent tumor reduction after chemotherapy had a 23.1 percent risk of progression or relapse within the first year. This is compared to 5.3 percent risk in patients whose tumor reduction was greater than 40 percent.

"We found that the combination of PET and relative tumor size reduction as determined by CT can identify patients at high risk for progression and early relapse," wrote Dr. Carsten Kobe of University Hospital of Cologne, Germany, and his associates.

Previous studies indicated that PET has good negative predictive value following chemotherapy in Hodgkin's patients, but that a positive PET scan, by itself, offers very little prognostic value.

Seeking to learn more about risk factors for progression, researchers took PET scans of 739 adults aged 18-60 years diagnosed with advanced-stage Hodgkin’s who had achieved only partial remission following 6-8 cycles of a dose-intensified BEACOPP (bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone).

A total of 548 (74 percent) patients who were PET negative experienced a 4-year progression-free survival rate of 91.5 percent, compared with 86.1 percent for PET-positive patients.

Researchers also noted that CT alone did not distinguish between high-risk and low-risk patients in either the PET-positive or PET-negative subgroups, but that those patients with less than 40 percent tumor reduction after chemotherapy had a 23.1 percent risk of progression or relapse within the first year, compared with 5.3 percent for patients with greater tumor reductions.

"In summary, the additional use of relative tumor size reduction helps to improve the positive predictive value of PET scanning after chemotherapy in advanced-stage [Hodgkin’s lymphoma] patients," they wrote. "This information might also help to identify a population of high-risk patients for whom alternative treatment options could be evaluated."

These findings were reported online in the Journal of Clinical Oncology.

Source: JCO