Relative tumor size improved predictive value of PET scans in advanced-stage Hodgkin’s lymphoma

Adults with advanced-stage Hodgkin’s lymphoma who achieved less than 40% tumor reduction after chemotherapy had a 23.1% risk of progression or relapse within a year, researchers reported online in the Journal of Clinical Oncology.

But when patients achieved at least 40% tumor reduction as measured by CT, their risk of progression or relapse in the next year was only 5.3%, reported Dr. Carsten Kobe of University Hospital of Cologne, Germany, and his associates.

"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," the investigators said.

Prior studies have shown that PET has good negative predictive value after chemotherapy in patients with Hodgkin’s lymphoma, but that a positive PET scan by itself has little prognostic value.

To better understand the risk factors for progression, the researchers performed PET scans on 739 adults aged 18-60 years with advanced-stage Hodgkin’s lymphoma who had achieved partial remission after six to eight cycles of a dose-intensified regimen of bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone.

Patients in partial remission had at least a 50% reduction in tumor volume but at least one nodal site measuring 2.5 cm or more in the maximal long-axis diameter as measured in the transversal or coronal axis on CT. Patients who were PET positive – defined as focal or diffuse uptake within residual tissue above the activity of mediastinal blood structures – underwent radiotherapy within 6 weeks of finishing chemotherapy. PET-negative patients did not undergo radiotherapy (J. Clin. Oncol. 2014 May 5 [doi: 10.1200/JCO.2013.53.2507]).

Among the 548 (74%) patients who were PET negative, 4-year progression-free survival was 91.5%, compared with 86.1% for PET-positive patients who received additional radiotherapy (P = .022), Dr. Kobe and his associates reported. They added that CT alone did not distinguish between high-risk and low-risk patients in either the PET-positive or PET-negative subgroups (P = .7 and .9, respectively). However, patients with less than 40% tumor reduction (as measured on CT) after chemotherapy had a 23.1% risk of progression or relapse within the first year, compared with 5.3% for patients with greater tumor reductions (risk difference, 17.9%; 95% confidence interval, 5.8%-30%), the investigators reported.

"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," the researchers concluded. "This information might also help to identify a population of high-risk patients for whom alternative treatment options could be evaluated."

Deutsche Krebshilf funded the study. The authors reported no conflicts of interest.

Adults with advanced-stage Hodgkin’s lymphoma who achieved less than 40% tumor reduction after chemotherapy had a 23.1% risk of progression or relapse within a year, researchers reported online in the Journal of Clinical Oncology.

But when patients achieved at least 40% tumor reduction as measured by CT, their risk of progression or relapse in the next year was only 5.3%, reported Dr. Carsten Kobe of University Hospital of Cologne, Germany, and his associates.

"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," the investigators said.

Prior studies have shown that PET has good negative predictive value after chemotherapy in patients with Hodgkin’s lymphoma, but that a positive PET scan by itself has little prognostic value.

To better understand the risk factors for progression, the researchers performed PET scans on 739 adults aged 18-60 years with advanced-stage Hodgkin’s lymphoma who had achieved partial remission after six to eight cycles of a dose-intensified regimen of bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone.

Patients in partial remission had at least a 50% reduction in tumor volume but at least one nodal site measuring 2.5 cm or more in the maximal long-axis diameter as measured in the transversal or coronal axis on CT. Patients who were PET positive – defined as focal or diffuse uptake within residual tissue above the activity of mediastinal blood structures – underwent radiotherapy within 6 weeks of finishing chemotherapy. PET-negative patients did not undergo radiotherapy (J. Clin. Oncol. 2014 May 5 [doi: 10.1200/JCO.2013.53.2507]).

Among the 548 (74%) patients who were PET negative, 4-year progression-free survival was 91.5%, compared with 86.1% for PET-positive patients who received additional radiotherapy (P = .022), Dr. Kobe and his associates reported. They added that CT alone did not distinguish between high-risk and low-risk patients in either the PET-positive or PET-negative subgroups (P = .7 and .9, respectively). However, patients with less than 40% tumor reduction (as measured on CT) after chemotherapy had a 23.1% risk of progression or relapse within the first year, compared with 5.3% for patients with greater tumor reductions (risk difference, 17.9%; 95% confidence interval, 5.8%-30%), the investigators reported.

"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," the researchers concluded. "This information might also help to identify a population of high-risk patients for whom alternative treatment options could be evaluated."

Deutsche Krebshilf funded the study. The authors reported no conflicts of interest.

Adults with advanced-stage Hodgkin’s lymphoma who achieved less than 40% tumor reduction after chemotherapy had a 23.1% risk of progression or relapse within a year, researchers reported online in the Journal of Clinical Oncology.

But when patients achieved at least 40% tumor reduction as measured by CT, their risk of progression or relapse in the next year was only 5.3%, reported Dr. Carsten Kobe of University Hospital of Cologne, Germany, and his associates.

"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," the investigators said.

Prior studies have shown that PET has good negative predictive value after chemotherapy in patients with Hodgkin’s lymphoma, but that a positive PET scan by itself has little prognostic value.

To better understand the risk factors for progression, the researchers performed PET scans on 739 adults aged 18-60 years with advanced-stage Hodgkin’s lymphoma who had achieved partial remission after six to eight cycles of a dose-intensified regimen of bleomycin, etoposide, doxorubicin, cyclophosphamide, vincristine, procarbazine, and prednisone.

Patients in partial remission had at least a 50% reduction in tumor volume but at least one nodal site measuring 2.5 cm or more in the maximal long-axis diameter as measured in the transversal or coronal axis on CT. Patients who were PET positive – defined as focal or diffuse uptake within residual tissue above the activity of mediastinal blood structures – underwent radiotherapy within 6 weeks of finishing chemotherapy. PET-negative patients did not undergo radiotherapy (J. Clin. Oncol. 2014 May 5 [doi: 10.1200/JCO.2013.53.2507]).

Among the 548 (74%) patients who were PET negative, 4-year progression-free survival was 91.5%, compared with 86.1% for PET-positive patients who received additional radiotherapy (P = .022), Dr. Kobe and his associates reported. They added that CT alone did not distinguish between high-risk and low-risk patients in either the PET-positive or PET-negative subgroups (P = .7 and .9, respectively). However, patients with less than 40% tumor reduction (as measured on CT) after chemotherapy had a 23.1% risk of progression or relapse within the first year, compared with 5.3% for patients with greater tumor reductions (risk difference, 17.9%; 95% confidence interval, 5.8%-30%), the investigators reported.

"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," the researchers concluded. "This information might also help to identify a population of high-risk patients for whom alternative treatment options could be evaluated."

Deutsche Krebshilf funded the study. The authors reported no conflicts of interest.