From the Journals

Imaging, radiotherapy clarified in new PMBCL guidelines



Fertility preservation, imaging and radiotherapy guidelines, and best practices in relapse or salvage therapy for primary mediastinal B-cell lymphoma (PMBCL) are all highlighted in a new good practice paper from the British Society for Haematology.

Though PMBCL was previously thought of as a subtype of diffuse large B-cell lymphoma, “gene expression profiling data has shown it to be a separate clinicopathological entity with evidence of an overlap with classic Hodgkin lymphoma,” said Kate Cwynarski, MD, PhD, of University College London Hospitals NHS Foundation Trust in England, and her coauthors. The recommendations were published in the British Journal of Haematology.

PMBCL makes up 2%-4% of non-Hodgkin lymphomas, they said; a bulky anterior mediastinal mass is the usual initial presentation. PMBCL does not usually spread beyond the thoracic cavity.

Biopsy, which should be reviewed by a hematopathologist, is required for a histological diagnosis of PMBCL. A multidisciplinary team should review the clinical presentation, pathology, and management plan, according to the good practice paper authors. This was a strong recommendation backed by a high level of evidence.

In addition, patients should receive positron emission tomography–computed tomography (PET/CT) at diagnosis, before steroids are administered, if possible, as standard of care. Results from the PET/CT should be reported in accordance with international guidelines. These strong recommendations are backed by high-quality evidence.

If PET/CT is performed, then “a bone marrow biopsy is not considered essential,” said Dr. Cwynarski and her coauthors. However, if the findings would influence management, such as when there is extranodal disease that presents central nervous system opportunities, then bone marrow biopsy should be performed. It should also be performed when cytotoxic therapy was initiated before PET/CT could be done. This is a weak recommendation supported by moderate evidence.

Since patients with PMBCL are usually young adults at presentation, it’s important to consider fertility preservation in the face of chemotherapy. For males, semen preservation should be offered. Female patients may not be able to postpone treatment long enough to accomplish egg harvesting. The risk of infertility and premature ovarian failure will depend on the treatment regimen, so “the risks of each individual therapeutic regimen should be discussed with the patient,” Dr. Cwynarski and her colleagues said.

If a patient is diagnosed with PMBCL while pregnant, treatment should be managed in conjunction with high-risk obstetrics and anesthesia specialists. Rituximab, cyclophosphamide, doxorubicin, vincristine, and prednisone (R-CHOP) has been used in pregnancy, and immunotherapy without antimetabolites can be considered in the second and third trimesters, according to the good practice paper. These are strong fertility and pregnancy recommendations, backed by moderate to low-quality evidence.

If superior vena cava obstruction causes thrombosis, local standard of care for anticoagulation should be used, but therapy-induced thrombocytopenia should be taken into consideration.

There is a lack of prospective, randomized studies to guide treatment decisions in PMBCL, according to the paper. Still, adding rituximab improves both response rates and duration of remission, they noted.

The standard of care for treatment is six cycles of R-CHOP and involved site radiotherapy (ISRT). If the patient is being cared for at a site that can manage the complexities of dose adjustment and monitoring, dose-adjusted etoposide, prednisone, vincristine, cyclophosphamide, doxorubicin, and rituximab (DA-EPOCH-R) without ISRT is an alternative, according to the good practice paper.

All patients should be offered clinical trial participation when feasible, a strong recommendation based on high-quality evidence.

To assess the response to therapy, R-CHOP and ISRT recipients not participating in a clinical trial should receive a PET-CT scan 2-3 months after treatment is completed, and DA-EPOCH-R patients should receive their scan 6 weeks after the end of therapy. For all patients, Deauville criteria should be used in reporting response scan results. These strong recommendations about posttherapy imaging are based on moderate-quality evidence.

The rate of relapse and refractory disease is relatively low at about 10%-30%, Dr. Cwynarski and her colleagues said. Relapse usually happens within the first year and is rare after 2 years; extranodal disease is common, but usually spares the central nervous system and bone marrow. The good practice paper authors strongly recommend, based on high-quality evidence, that biopsy and fluorodeoxyglucose-PET/CT should be performed with relapse.

Radiotherapy can be considered if the relapse is localized and the patient didn’t receive initial radiotherapy, a strong recommendation with moderate evidence to support it.

Salvage regimens for patients who have not previously achieved complete metabolic response lack a disease-specific evidence base, noted Dr. Cwynarski and her colleagues. Taking this into consideration, a PMBCL salvage regimen should be the same as that offered to patients with relapsed diffused large B-cell lymphoma. High-dose therapy and autologous stem cell transplantation is appropriate for responsive disease.

If radiotherapy had not been given previously, it should be considered either pre- or post transplant. This, along with the other salvage therapy guidance, is a weak recommendation, backed by moderate evidence.

For longer-term follow-up, asymptomatic patients should not have routine imaging, a strong recommendation with moderate evidence. “[P]atients who remain in remission may be considered for discharge back to primary care,” Dr. Cwynarski and her coauthors said, making a weak recommendation based on low-quality evidence. Patients and their primary care providers should know about the potential for such long-term complications as cardiac toxicities and second malignancies.

SOURCE: Cwynarski K et al. Br J Haematol. 2019 Jan 4. doi:10.1111/bjh.15731

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