Читать книгу Intracranial Gliomas Part III - Innovative Treatment Modalities - Группа авторов - Страница 21

Stereotactic interstitial PDT was applied for management of 27 deep-seated HGG (GBM 19 cases; AA 8 cases) in 24 patients (13 men and 11 women aged from 20 to 78 years). There were 3 newly diagnosed and 24 recurrent neoplasms after one or several relapses. The tumors usually were small and affected eloquent brain structures, thus were considered unresectable. The volume of the mass was within 1–5 cm³ in 16 cases (59%), 5.1–10 cm³ in 3 cases (11%), 10.1–15 cm³ in 1 case (4%), and >20 cm³ in 7 cases (26%). In 11 patients, the tumor affected basal ganglia.

Photofrin^® at a dose of 2 mg/kg was administered intravenously approximately 48 h prior to interstitial photo-irradiation. To perform PDT an optical fiber was inserted directly into the tumor under stereotactic guidance. A Brown-Roberts-Wells (BRW) stereotactic frame was fixed on the patient’s head, and an MRI was performed under stereotactic conditions. Target points for the tip of the optical fiber for photo-irradiation were planned to be located within approximately 10 mm apart from each other. Their number depended on the tumor size. The patient was transferred to the operating theater. Burr holes were made under local anesthesia and an optical fiber (450 μm in diameter) was inserted under stereotactic guidance into the target point. Photo-irradiation was performed using a semiconductor laser beam with the wavelength of 635 nm and power of 200 mW during 15 min (energy 180 J). Upon completion of photo-irradiation at one target point, the same procedure was performed in others using the same technical parameters.

Table 2. Response of malignant gliomas to interstitial photodynamic therapy with Photofrin^®

Treatment was well tolerated by all patients. Cerebral edema was noted in 11 cases (46%), but usually was mild (10 cases) and did not require any specific treatment. It was recommended that patients avoid direct sunlight during the 3 weeks after PDT.

Volumetric tumor response was assessed on post-contrast MRI at 4 weeks after PDT (Table 2). Mass volume reduction was demonstrated in all patients. Complete response was noted in 16 cases (59%), partial response (from 50 to 99% volume reduction) in 8 (30%), and minor response (<50% volume reduction) in 3 (11%). Response to treatment was associated with the size of the tumor. All neoplasms with the volume of ≤5 cm³ demonstrated complete response, and all with the volume of ≤15 cm³ showed either complete or partial response. In contrast in 7 tumors with a volume >20 cm³ there were no complete responses and only 4 (57%) partial responses. Tumors with minimal response to treatment had volumes >23 cm³. Mean TTP after PDT was 7 months in the entire cohort, and 11 months in patients who achieved complete response (Fig. 1). One patient with GBM and another one with AA were alive without recurrence for more than 10 years after PDT.