Clinical emergence of neurometastatic merkel cell carcinoma: a surgical case series and literature review

Merkel cell carcinoma (MCC) is a rare cutaneous neuroendocrine neoplasm of possible viral origin and is known for its aggressive behavior. The incidence of MCC has increased in the last 15 years. Merkel cell carcinoma has the potential to metastasize, but rarely involves the central nervous system. Herein, we report three consecutive surgical cases of MCC presenting at a single institution within 1 year. We used intracavitary BCNU wafers (Gliadel®) in two cases. Pathological features, including CK20 positivity, consistent with MCC, were present in all cases. We found 33 published cases of MCC with CNS involvement. We suggest that the incidence of neurometastatic MCC may be increasing, parallel to the increasing incidence of primary MCC. We propose a role for intracavitary BCNU wafers in the treatment of intra-axial neurometastatic MCC

Recent progress towards development of effective systemic chemotherapy for the treatment of malignant brain tumors

Systemic chemotherapy has been relatively ineffective in the treatment of malignant brain tumors even though systemic chemotherapy drugs are small molecules that can readily extravasate across the porous blood-brain tumor barrier of malignant brain tumor microvasculature. Small molecule systemic chemotherapy drugs maintain peak blood concentrations for only minutes, and therefore, do not accumulate to therapeutic concentrations within individual brain tumor cells. The physiologic upper limit of pore size in the blood-brain tumor barrier of malignant brain tumor microvasculature is approximately 12 nanometers. Spherical nanoparticles ranging between 7 nm and 10 nm in diameter maintain peak blood concentrations for several hours and are sufficiently smaller than the 12 nm physiologic upper limit of pore size in the blood-brain tumor barrier to accumulate to therapeutic concentrations within individual brain tumor cells. Therefore, nanoparticles bearing chemotherapy that are within the 7 to 10 nm size range can be used to deliver therapeutic concentrations of small molecule chemotherapy drugs across the blood-brain tumor barrier into individual brain tumor cells. The initial therapeutic efficacy of the Gd-G5-doxorubicin dendrimer, an imageable nanoparticle bearing chemotherapy within the 7 to 10 nm size range, has been demonstrated in the orthotopic RG-2 rodent malignant glioma model. Herein I discuss this novel strategy to improve the effectiveness of systemic chemotherapy for the treatment of malignant brain tumors and the therapeutic implications thereof

Patients undergoing surgery of intracranial metastases have different outcomes based on their primary pathology

OBJECTIVES: Patients with a variety of different primary cancers can develop intracranial metastases. Patients who develop intracranial metastases are often grouped into the same study population, and therefore an understanding of outcomes for patients with different primary cancers remain unclear. METHODS: Adults who underwent intracranial metastatic tumor surgery from 1997–2011 at a single institution were retrospectively reviewed. Primary pathologies were compared using Fisher’s exact and Student’s t-test, and Cox regression analysis was used to identify factors associated with survival. RESULTS: About 708 patients underwent surgery during the reviewed period, where 269 (38%) had non-small cell lung cancer (NSCLC), 106 (15%) breast cancer (BC), 72 (10%) gastrointestinal (GI) cancers, 88 (12%) renal cell cancer (RCC), and 88 (12%) melanoma. The most notable differences were that NSCLC patients were older, BC younger, BC had more primary tumor control, and NSCLC less extracranial spread. BC had longer survival, RCC had longer local progression free survival (PFS), and NSCLC had longer distal PFS. The factors independently associated with survival for NSCLC (female, recursive partitioning analysis (RPA) class, primary tumor control, solitary metastasis, tumor size, adenocarcinoma, radiation, discharge to home), BC (age, no skull base involvement, radiation), GI cancer (age, RPA class, Karnofsky performance scale (KPS), lack of preoperative motor deficit, non-esophageal tumors, non-hemorrhagic tumors, avoidance of new deficits), melanoma (preoperative seizures, solitary metastasis, smaller tumor size, discharge to home, chemotherapy), and RCC (KPS, chemotherapy) were distinctly different. DISCUSSION: These differences between patients with different primary cancers support the fact that patients with intracranial disease are not all the same and should be studied by their primary pathology