The goal of this research is to improve the accuracy of predicting the breast cancer (BC) pro- cess using the original mathematical model referred to as CoMPaS. The CoMPaS is the original mathematical model and the corresponding software built by modelling the natural history of the primary tumor (PT) and secondary distant metastases (MTS), it reflects the relations between the PT and MTS. The CoMPaS is based on an exponential growth model and consists of a system of determinate nonlinear and linear equations and corresponds to the TNM classification. It allows us to calculate the different growth periods of PT and MTS: 1) a non-visible period for PT, 2) a non-visible period for MTS, and 3) a visible period for MTS. The CoMPaS has been validated using 10-year and 15-year survival clinical data con- sidering tumor stage and PT diameter. The following are calculated by CoMPaS: 1) the number of doublings for the non-visible and visible growth periods of MTS and 2) the tumor volume doubling time (days) for the non-visible and visible growth periods of MTS. The diameters of the PT and secondary distant MTS increased simultaneously. In other words, the non-visible growth period of the secondary distant MTS shrinks, leading to a decrease of the survival of patients with breast cancer. The CoMPaS correctly describes the growth of the PT for patients at the T1aN0M0, T1bN0M0, T1cN0M0, T2N0M0 and T3N0M0 stages, who does not have MTS in the lymph nodes (N0). Additionally, the CoMPaS helps to con- sider the appearance and evolution period of secondary distant MTS (M1). The CoMPaS correctly describes the growth period of PT corresponding to BC classification (parameter T), the growth period of secondary distant MTS and the 10-15-year survival of BC patients considering the BC stage (parameter M).

Electrocorticography (ECoG) is a standard procedure for the localization of the epileptogeniczone during the surgical treatment of symptomatic epilepsy. The purpose of this study was to evaluate the diagnostic efficacy of intraoperative pre- and post-resective ECoG for the localization of the epileptogenic zone in patients with symptomatic epilepsy associated with supratentorial brain tumors. 1. In the surgical treatment of symptomatic epilepsy associated with intracerebral neoplasm, intraoperative ECG remains a relatively effective method. 2. The effectiveness of intraoperative pre- and post-resection ECoG is affected by factors associated with the performance of neurosurgical surgery (the influence of general anesthetics, mechanical effects on the brain, repeated electrocoagulation), which significantly alter the index of epileptiform activity.

Objective Removal of brain tissue generating pathological high-frequency oscillations (pHFOs) has been related to better seizure outcome than resection of seizure onset zone. However, there is still a lack of understanding what oscillations are to be considered pathological. Methods A female patient (age 53) with 10 year duration of temporal lobe tumor-related epilepsy was admitted to Polenov’s Neurosurgery Institute for tumor resection. The patient underwent a two-staged surgery with subdural implantation of a grid electrode (4 × 5) over the temporal lobe to identify the epileptogenic zone (EZ). During the second stage wideband intraoperative electrocorticography (iECoG) was recorded (up to 500 Hz, sampling frequency 2000 Hz, Mitsar-EEG 202 amplifier). Results Electrocorticographic monitoring data were subjected to visual analysis in traditional frequency range (0.5–70 Hz). Six of 20 electrodes were marked as EZ electrodes. The distance between tumor margin and EZ electrodes reached 1–2.5 cm. Subpial resection of this zone was arranged. During the surgery iECoG data in 0.5–70 Hz frequency band were uninformative, while in 80–500 Hz range bursts of fast ripples (250–500 Hz, 100 μV, extended up to 3 s) were recorded over the marked EZ electrodes. The tumor and EZ were completely resected. Discussion Observed data demonstrate that HFOs coincide with EZ marked during long-term monitoring. The patient is seizure-free for 5 months at the moment, though a more prolonged follow-up is required. Conclusion Wideband iECoG recordings might give us more essential information in case of tumor-related epilepsy. As is shown, fast ripples may be a valid marker of EZ. Significance Pathological HFOs show promise for optimising epilepsy surgery in tumor-related epilepsy.