Dissertation for the degree of candidate of Medical Sciences, specialty 14.01.23 ― Radiation Diagnosis and Radiation Therapy. ― P.L. Shupik National Medical Academy of Post-Graduate Education, Kyiv, Ukraine, 2021.
The dissertation is based on the analysis of the results of treatment of 117 patients who were treated in the period from 2010 to 2014 with stereotactic radiosurgery for skull base meningiomas in the Department of Radioneurosurgery of the State Institution "Institute of Neurosurgery named after. acad. A.P. Romodanov NAMS of Ukraine".
The dissertation is devoted to the decision of an actual scientific problem of increase of efficiency of radiosurgical treatment of meningiomas of a basis of a skull.
In the dissertation, based on the analysis of the results of radiosurgical treatment of 117 patients with skull base meningiomas and post-radiation neuroimaging monitoring data, the effectiveness of radiosurgical treatment results is increased by improving (modifying) stereotactic irradiation techniques and justifying the use low-dose irradiation.
In our material, there were 23 (19,7%) men and 94 (80,3%) women among the patients, ie there was a predominance of women. The average age of patients in general was 53,9 years.
Among the irradiated 119 SBM meningiomas of petroclival localization occurred in 37 (31,1%) cases; meningiomas of the cavernous sinus ― in 50 (42%) patients; meningiomas with localization in the area of the pons-cerebellar angle (PCA) were registered in 19 (16%) cases; 13 (10,9%) meningiomas had paracellar localization.
In 21 (17,6%) cases, SRS was performed in patients after subtotal resection of the tumor. The diagnosis of SBM was confirmed histologically in 21 (17,6%) cases after open surgery. In another 98 (82,4%) cases, the diagnosis was established on the basis of long-term history, relevant clinical symptoms, instrumental examination data and neuroimaging studies.
When performing SRS, the mean value of the target volume was 7,41 cm3 with 95% CI [6,49; 8,34]. The average prescribed dose was 12,55 Gy with 95% CI [12,40; 12,69]. The average value of the relative volume of the target that received PD was 96,2% with 95% CI [95,37; 97,03]. When performing SRS, the maximum dose averaged 14,45 Gy with 95% CI [14,15; 14,76].
Among the techniques used in the performance of SRS, dominated by 70% using irradiation techniques such as the Intensity-modulated radiotherapy (IMRT) and the method of combining irradiation with intensity modulation and conformal dynamic rotation (IMRT + MLC Dyn Arc) аt 36% and 34% respectively. in only 4% of cases the method of static conformal irradiation (Conf MLC) was used. Other techniques, such as the technique of irradiation with conformal static fields using collimators of different diameters (Arc cone) and the technique of irradiation with rotation of the gentry and dynamic adjustment of the collimator to the shape of the tumor (Dynamic Arc MLC) were used in 13% of cases each.
The local control (LC) of the growth of the skull base meningiomas after SRS for a median follow-up of 43 months is achieved in 90% of cases, indicating a high efficiency of the method for the treatment of this pathology.
The paper substantiates the use of a modified irradiation technique with intensity modulation and conformal dynamic rotation (IMRT + MLC Dyn Arc), which increases the intensity of achieving long-term LC by 1,61 times compared with standard methods of radiosurgical irradiation [HR = 1.61 [1,1; 2,3]) and is a predictor for achieving LC (p=0,041).
The number of patients after stereotactic radiosurgery with a rate of 90% on the scale (index) Karnofski increases from 41,9% to 70,9%. The absence of deterioration of functional status on the scale (index) of Karnofski after radiosurgical treatment is 97% of observations, including 50% of patients have an improvement in functional status.
There was no statistically significant difference between the low-dose (prescribed dose <12,5 Gy) irradiation regimen and the high-dose irradiation regimen (prescribed dose> 12,5 Gy) in terms of the effectiveness of achieving local tumor growth control (p=0,09).The use of low-dose irradiation is associated with an increase in the frequency of regression of the irradiated tumor after pseudoprogression of 30% vs. 5,3%, respectively (p=0,04).
There was a statistically significant difference between the group of patients with a large tumor volume (> 8,3 cm3) and the group with a smaller volume (<8,3 cm3) relative to the incidence of pseudoprogression 21,1% vs. 7,4%, respectively (p=0,004).
A diagnostic test has been developed to predict the safety of SRH treatment, shows that the location of the tumor "posterior cranial fossa + middle cranial fossa" always corresponds to a high risk of complications, regardless of the strength of the tumor response to CPH. The safest option is when the localization corresponds to the middle cranial fossa (the highest sensitivity of the tumor).
