Treatment of disorder
Around 9% of patients under cancer treatment has metastasis. Occurrence rate is in the order of lung cancer (51%), breast cancer (10%), rectal cancer, stomach cancer, and bowel cancer. There are around 10% for unknown primary lesion. Metastasis may develop carcinomatous meningitis by disseminating cancer cell intrathecally. Prognosis has reported one to two months in case of no treatment. When prognosis is considered within 3 months with the status of cancer lesion outside of the brain, surgery is not subject for this case in general. Lung cancer or Breast cancer is common in primary lesion, and it metastasize to intraparenchymal, cranial bone, dura matter, spinal vertebral body and spinal cord. (Fig.1) Metastasis to bone is generally osteoclastic, but prostate cancer is osteophytosis.
As already mentioned in malignant glioma section, treatment for both metastatic lesion in the intraparenchymal and carcinomatous meningitis are necessary. In no treatment case, at longest 3 to 6 months are given to live.
Above are the basic line of treatment, but when primary lesion is treated and in case the number of metastasis lesion is less than three, exenterate when possible and there is a thought where whole-brain irradiation or chemotherapy later is better. Writer agrees with this idea so that performing the treatment accordingly. As for metastasis lesion exenteration, in case when tumor is cut to the limit of its boundary, there is a possibility for existing a remaining tumor around, so that if possible, it is necessary to try cutting to include the surrounding tissue.
Regarding the irradiation treatment for brain metastasis lesion, there is no superior treatment than irradiation therapy. For metastatic brain tumor, stereotactic irradiation (machine exposes radiation in focus to certain consistent area), such as gamma knife, X-knife, Cyber Knife, or I-MRT are performed. But by only stereotactic irradiation may have the possibility of developing new metastasis lesion, in this case, recurrence of entire body chemotherapy will have an effect. Also, the trial is made with the combination of whole-brain irradiation, but conclusion is not yet achieved. As for the stereotactic irradiation, there is a issue of bleeding from tumor so that careful attention is necessary.
Chemotherapy efficacy is recognized depend on the type of Cancer. Especially for the case of brain metastasis by chemotherapy effective type tumor, like lung cancer (in particular small cell cancer), breast cancer, or embryonic cell tumor, it is expected to reduce in tumor size, as same as primary lesion. Effective chemotherapy for primary lesion is, at the stage of brain metastatic lesion is treated, repetition of chemotherapy shows effect to the unsaturated metastatic lesion, and to extend survival duration. (Nakagawa H, et al., J Neurol Neurosurg Psychiatry 57:950-956,1994), and recognized many long-term survivor cases. （proceedings 12th world congress of neurosurgery, Sydney, Australia, WFNS 2001:544-547）.Treatment for intraspinal dissemination (carcinomatous meningitis) becomes very important other than the chemotherapy for intraparenchymal metastasis.
In regards to prognostic factor analysis, Sperduto et al, made the announcement of Graded Prognostic Assessment（GPA）by the factor of existence or non-existence of KPS, number of brain metastasis, age and intracranial metastasis, using RTOG Clinical data, and then they had further extended to each primary cancer typed Diagnostic-Specific （DS） GPA. In DS-GPA sets the prognosis factor and points for each lesion type, like lung cancer, malignant melanoma, renal cell cancer, digestive system cancer, breast cancer, and also survival duration can be predicted.
For the case where metastasis is single and KPS (over 70) is in good, surgery + whole brain irradiation is recommended, but for tumor in less 3cm diameter, same effect is expected with SRT (+ forebrain exposure).In case whole brain exposure is added to surgery or SRT, duration for recurrence (regional intra-brain and remote area recurrence) can be extended, it is said there is no significant difference. It is considered that the necessity of chemotherapy exists in this case.
Since the QOL in whole brain exposure or decline in cognitive function become concerned, SRT single treatment can be selected at less 3 to 4 pieces.In chemotherapy, some shows efficacy for brain metastasis among molecularly targeted drug or chemotherapy agent, it is expected for the future development.In non-small cell cancer having Epidermal Growth Factor Receptor mutation, effect of the combination therapy using lapatinib or capecitabine is reported, and for metastatic brain tumor patient by HER2 positive breast cancer, combination therapy using gefinitib or erlotinib is reported.
In any case, combined modality therapy, like surgery radiation and chemotherapy, is necessary as the treatment for metastatic brain tumor, and long-term survival is expected by the positive treatment. Fig. 8 shows the case where lung cancer metastasizes to orbital area, but with alcohol injection to tumor under ultrasound echo, it can be extracted with less bleeding and tumor has almost disappeared by radiation chemotherapy after surgery.
As to other interesting metastasis of cancer, there are many cases where subdural hemorrhage is often diagnosed as chronic subdural hematoma, but if thoroughly observed it can be diagnosed, but often it is mistaken.
There is brain metastasis or bone metastasis of lung cancer. It is easy to bleed, and extraction becomes extremely hard when it locates intracranially. Above picture shows, first alcohol is injected inside tumor under ultrasound echo, then after that it is extracted.