Primary CNS lymphoma relative to chemotherapy
Just to give you an idea of what types of responses you can have. This is a 52-year-old man, presented with a huge mass in his right temporal parietal lobe. This was found on biopsy to be a CNS lymphoma and after two cycles on a regimen that we use, consisting of high dose methotrexate, cyclophosphamide and vincristine, after two cycles this was his scan.
This is before radiation therapy. So again a very satisfying disease to treat.
There remain a number of questions of primary CNS lymphoma relative to chemotherapy, such as who benefits from chemotherapy? We talked about the issue of immunocompetent versus immunodeficient patients. Prognostic factors seem to make a difference, with age being the most important. That elderly patients do not tolerate the chemotherapy as well or they don’t tolerate the chemotherapy side effects, and indeed they do not appear to benefit as much as younger patients. But what the age cut-off is and why this should be the case remains totally unknown. Issues relative to performance status, pathology and extent of disease appear to be less significant, at least for immunocompetent patients being treated with chemotherapy. There also continue to be significant and growing questions about the appropriate role for radiotherapy, such as what is the optimal dose and fractionation scheme, since combining chemotherapy and radiation now patients are living longer, one begins to have to worry about long term neuro-cognitive sequelae. One is beginning to question, with optimal chemotherapy, does one even need to use radiation therapy. So these are questions that still remain outstanding in primary CNS lymphoma. Again, a difficult problem in answering these questions given the relative rarity of the disease.
I’d like to just finish up by talking a little bit about, and mentioning a few of the recent developments, in the treatment of brain metastasis. A problem that medical oncologists obviously see quite frequently. The reason for that is that 20-40% of all cancer patients will develop brain metastases, accounting for 170,000 cases per year. The majority of these patients have lung cancer. Most of the metastases occur in the gray white matter, of which 80% is supratentorial. The few tumor types that can metastasize to the dura are breast and prostate, while the two tumor types that appear as hyperdense lesions without contrast are renal cell carcinoma, melanoma and actually sarcoma. But most of the other metastases appearing as hypo or iso-dense lesions.