A 35-year-old woman is diagnosed with diffuse large B-cell lymphoma (DLBCL) with IPI score of 2 (low-intermediate risk). Staging CT shows stage II disease with no CNS involvement. What is the drug of choice / first-line regimen for this patient?

Explanation

## Diagnosis: Diffuse Large B-Cell Lymphoma (DLBCL) — Low-Intermediate Risk **Key Point:** R-CHOP is the gold-standard first-line regimen for DLBCL in fit patients, regardless of stage or IPI score. The addition of rituximab (anti-CD20 monoclonal antibody) to CHOP significantly improves overall survival and disease-free survival. ### Evidence for R-CHOP **High-Yield:** Landmark trials (RICOVER-60, MInT) demonstrated that: 1. R-CHOP improves 5-year overall survival to ~70–80% in DLBCL 2. Rituximab monotherapy is insufficient for DLBCL 3. CHOP without rituximab is now considered substandard 4. R-CHOP is tolerated well in fit patients aged 18–80 years ### Regimen Components | Component | Mechanism | Role | |-----------|-----------|------| | Rituximab | Anti-CD20 monoclonal antibody | Targets B-cell antigen; improves survival | | Cyclophosphamide | Alkylating agent | DNA cross-linking | | Doxorubicin | Anthracycline | Intercalates DNA; topoisomerase II inhibitor | | Vincristine | Vinca alkaloid | Microtubule inhibitor | | Prednisolone | Corticosteroid | Immunosuppression; apoptosis induction | **Clinical Pearl:** R-CHOP is typically given every 21 days for 6–8 cycles. Prophylactic G-CSF is often used to prevent febrile neutropenia. ### Why Other Options Are Incorrect **CHOP alone (option 1):** Historical regimen; now considered substandard. Rituximab addition improves outcomes significantly and should not be omitted in CD20+ DLBCL. **Rituximab monotherapy (option 2):** Insufficient for DLBCL. Monotherapy has response rates <50% and is used only in specific scenarios (e.g., small lymphocytic lymphoma, follicular lymphoma with low tumor burden). **Etoposide and dexamethasone (option 3):** Not standard for DLBCL. This combination may be used for salvage therapy (e.g., DHAP in relapsed/refractory disease) or for CNS prophylaxis, but not as first-line. **Mnemonic:** **R-CHOP for DLBCL:** - **R** = Rituximab (anti-CD20) - **C** = Cyclophosphamide - **H** = doxorubicin (Hydroxydaunorubicin) - **O** = Oncovine (vincristine) - **P** = Prednisolone **High-Yield:** Even in elderly patients (>60 years), R-CHOP is preferred over CHOP alone; dose modifications may be needed based on comorbidities and renal/hepatic function.