Lymphomas primarily occur in the CNS or affect the CNS as part of a generalized disease.
Radiation treatment of intracerebral, intraspinal, or meningeal/cerebrospinal fluid lymphoma manifestations may be appropriate as one or more treatment alternatives. This treatment is often part of a multimodal approach in combination with systemic and intrathecal/intraventricular chemotherapy.
Radiation treatment can be given to the entire CNS axis (brain, spinal cord, and cerebrospinal fluid space down to the S1/2 level, sometimes including both eye sockets and optical nerves) or only the brain with surrounding liquor space. Due to the diffuse growth and tendency for meningeal involvement of lymphomas, whole brain radiation is almost always indicated. Radiation of only parts of the brain or a boost to parts of the brain is normally not recommended.
Radiation therapy to cure the disease
Radiation therapy to the whole brain can be given as a part of multimodal curative treatment in:
- Primary CNS lymphomas (PCNSL) - In younger patients (< 60 years), radiation to the brain is often included in treatments where CNS-directed chemotherapy is followed by radiation therapy. The role that radiation therapy plays, as well as the total dosage and fractioning , is uncertain. At the Oslo University Hospital, we use the protocol from Memorial Sloan Kettering Cancer Center. In older patients, a combination with chemotherapy often causes significant neurotoxicity, therefore radiation therapy is used with caution and preferably reserved for patients who do not achieve effect from chemotherapy, or for recurrence of the disease. For a multi-modal treatment arrangement for PCNSL, it is generally not recommended to administer radiation treatment to the spinal cord, even if lumbar puncture has shown more generalized meningeal spreading of tumor cells. If the eye ball is not known to be involved, it is not included in the radiation field. A new nordic protocol for PCNSL is under planning where radiation is not used as the primary treatment, for both older or younger patients.
- Treatment/prophylaxis of CNS manifestations for acute lymphoblastic leukemia and Burkitt's lymphoma - For treatment/prophylaxis of a CNS disease as part of treatment to cure acute lymphoblastic leukemia, radiation treatment may be included. It is often combined with CNS-directed chemotherapy/intrathecal treatment. It may be appropriate (but not obligatory) to give radiation to the spinal cord simultaneously.
- Treatment/prophylaxis of CNS manifestation from several other malignant lymphomas: In other malignant lymphomas where the CNS is involved, radiation treatment to the brain is considered individually as part of the treatment plan to cure the disease. If there is meningeal spreading or findings in the spinal cord, it may be appropriate to add radiation treatment to the spinal cord.
Palliative radiation therapy
- For palliative radiation therapy, the method generally follows the same guidelines as for curative treatment, with individual adjustments.
In younger patients (< 60 years), radiation to the brain is often included in treatments where CNS-directed chemotherapy is followed by radiation therapy. The role that radiation therapy plays, as well as the total dosage and fractioning, is uncertain.
The curative schedule after chemotherapy with hyperfractionated treatment may have possible advantages. At Oslo University Hospital (Radiumhospitalet), the treatment schedule from MSKCC is used. In elderly patients, a combination of chemotherapy of this kind often causes significant neurotoxicity, and radiation therapy should be used with caution, preferably reserved for patients with poor response to chemotherapy or with recurrence.
For multimodal treatment for PCNSL, radiation therapy is normally not given to the spinal cord, even if lumbar puncture has shown more generalized meningeal scattering of tumor cells. If there is no known involvement of the bulb of the eye, the eye is not included in the radiation field. A new Nordic protocol for PCNSL is planned where radiation therapy will not be used during primary treatment, either for elderly or younger patients.
For treatment/prophylaxis for CNS disease as part of the curative treatment arrangement for ALL/lymphoblastic disease, lower doses are preferably used (18–24 Gy in 1.8–2 Gy per fraction), often in combination with CNS-directed chemotherapy/intrathecal treatment. Simultaneous radiotherapy to the spinal cord is often given (but not obligatory).
For other malignant lymphomas with CNS involvement, radiotherapy to the brain is considered, either as part of a curative or palliative plan. In cases of meningeal scattering of tumor cells or findings in the spinal cord, radiation therapy of the spinal cord may also be given.