Hematopoietic Stem Cell Transplant (HSCT) as Primary Treatment for T-Cell Lymphobastic Lymphoma (T-LBL) : An Intention to Treat Analysis.

The role of HSCT for T-LBL is not well defined. Most series are subject to referral bias and do not address the true impact of HSCT, especially as primary treatment. Since 1987 all patients in British Columbia with T-LBL have been considered eligible for HSCT as part of primary treatment. Between 6/87–12/03, 27 patients were diagnosed with T-LBL. Patients with > 25% involvement of the bone marrow were excluded.

Characteristics: Age range 18–56 y (median 26); M:F 19:8; Ann Arbor stage I-II 6; III-IV 21; bone marrow involved 7/27; peripheral blood involved 2/27; CNS involved 1/27; LDH elevated 15/25; mediastinal mass 23/27.

Initial treatment: All received an anthracycline-containing regimen similar to CHOP. All achieved at least a partial remission.

HSCT: 23/27 (85%) proceeded to HSCT in first response.

Source of stem cells: 4, related donor (2 marrow, 2 peripheral blood); 19, autologous (15, mafosphamide purged marrow; 1, 4-hydroperoxy-cyclophosphamide purged marrow; 1, unpurged marrow; 1, unpurged peripheral blood; 1, combined unpurged marrow and peripheral blood). Conditioning was cyclophosphamide (150 mg/kg) and TBI (750–1200 cGy) +/− etoposide 1.8 g/m2 in 22 of 23 patients. CNS prophylaxis with intrathecal methotrexate and cytarabine was planned for all patients. All 23 had maintained chemosensitivity at time of HSCT. Time from diagnosis to HSCT was 1.3–6.4 months (median 2.2). Reasons for not proceeding to HSCT 2 refused; 1 decided to wait until relapse; 1 did not have adequate organ function. Median follow-up of living patients was 33 months (range 4–142 months).

Results: Overall survival (OS) and event free survival (EFS) at 3 years for all patients were 79% (95% CI 61–97%) and 75% (95% CI 57–93%); patients who underwent HSCT 85% (95% CI 70–100%) and 81% (95% CI 64–98%). 4 patients relapsed post HSCT at 2.2, 10.8, 11.7 and 40.4 months post HSCT.

Sites of relapse: 2, mediastinum; 1, bone marrow; 1, mediastinum and bone marrow. One patient who received HSCT died of a treatment related complication (interstitial pneumonitis). Significant factors for improved survival post HSCT (univariate): Absence of bone marrow involvement [EFS at 3 years 92% vs 57% (p=0.026)].

Non-significant factors: normal LDH, stage I/II at diagnosis, age < 30 yrs.

Conclusions: Patients with T-cell lymphoblastic lymphoma treated with a CHOP-like regimen achieve adequate control of disease to proceed to HSCT. HSCT as primary treatment results in excellent long-term disease free survival with acceptably low treatment related mortality. Bone marrow involvement at diagnosis, even though < 25%, predicts for a worse outcome.