Induction chemotherapy strategies for primary mediastinal large B-cell lymphoma with sclerosis: a retrospective multinational study on 426 previously untreated patients.

Background and Objectives: This multinational retrospective study compares the outcomes of patients with primary mediastinal large B-cell lymphoma (PMLBCL) with sclerosis after first-generation (dose-intensive regimens), third-generation (alternating regimens) and high-dose chemotherapy strategies, frequently with adjuvant radiation therapy.
Design and Methods: Between August 1981 and December 1999, a total of 426 previously untreated patients with confirmed diagnosis were enrolled in 20 institutions to receive combination chemotherapy with either first generation (CHOP or CHOP-like) regimens, third generation (MACOP-B, VACOP-B, ProMACE CytaBOM) regimens or high-dose chemotherapy (HDS/ABMT).
Results: With chemotherapy, complete response (CR) rates were 49% (50/105), 51% (142/277) and 53% (23/44) with first generation, third generation and high-dose chemotherapy strategies, respectively; partial response (PR) rates were 32%, 36% and 35%, respectively. All patients who achieved CR and 124/142 (84%) with PR had radiation therapy on the mediastinum. The final CR rates became 61% for CHOP/CHOP-like regimens, 79% for MACOP-B and other regimens, and 75% for HDS/ABMT. After median follow-ups from attaining CR of 48.5 months for CHOP/CHOP-like regimens, 51.7 months for MACOP-B type regimens and 32.4 months for HDS/ABMT, relapses occurred in 15/64 (23%), 27/218 (12%) and 0/33 (0%) patients, respectively. Projected 10-year progression-free survival rates were 35%, 67% and 78%, respectively (p=0.0000). Projected 10-year overall survival rates were 44%, 71% and 77%, respectively (p=0.0000), after median follow-ups from diagnosis of 52.3 months, 54.9 months and 35.8 months, respectively.
Interpretation and Conclusions: In patients with PMLBCL with sclerosis, MACOP-B plus radiation therapy may be a better strategy than other treatments; these retrospective data need to be confirmed by prospective studies. The encouraging survival results after high dose chemotherapy require confirmation in selected high-risk patients.