1,721,031 research outputs found
Estimating the growth kinetics of experimental tumours from as few as two determinations of tumour size: implications for clinical oncology
No full textClinical information on tumor growth is often limited to a few determinations of the size of the tumor burden taken at variable time. As a consequence, fitting of growth equations to clin- ical data is hampered by the small number of available data. On the other hand, characterising the tumor growth kinetics in terms of clinically relevant parameters, such as the doubling time of the tumors, is increasingly required to optimize and personalise treat- ments. A computational method is presented which can estimate the growth kinetics of tumors from as few as two determinations of its size taken at two successive time points, provided the size at which tumor growth saturates is known. The method is studied by using experimental data obtained in vitro with multicell tumor spheroids and in vivo with tumors grown in mice, and its outputs are compared to those obtained by fitting of experimental data with the Gompertz growth equation. Under certain assumptions and limitations the method provides comparable estimates of the doubling time of tumors with respect to the classical nonlinear fit- ting approach. The method is then tested against simulated tumor growth trajectories spanning the range of tumor sizes observed in the clinics. The simulations show that a relative classification of tu- mors on the basis of their growth kinetics can be obtained even if the size at which tumor growth saturates is not known. This re- sult opens the possibility to classify patients bearing fast or slow growing tumors and, hence, to adapt therapeutic regimens under a more rationale basis
The role of Gamma Knife radiosurgery in the treatment of primary and metastatic brain tumors
No full textWith the widespread diffusion of stereotactic radiosurgical procedures, GKR treatments have gained considerable momentum as a major therapeutic option for patients harboring primary or metastatic brain tumors. Present results in high grade gliomas indicate a potential palliative role of this technique. The overall low radiosensitivity of these oncotypes and their infiltrative nature-with the resulting problems in properly defining the tumor target-are still a major obstacle to further development of the approach. In this regard, useful contributions are expected from advances in molecular neurobiology and functional neuroimaging as shown by preliminary investigations with MR spectroscopy. Surgery maintains a dominant role in the therapeutic armamentarium for low grade gliomas. However, in unfavorable cases (unresectable tumors, recurrences), GKR seems to be an effective alternative to conventional radiochemotherapy. In grade 2 astrocytomas and specifically in grade 1 pilocytic forms, short-to-mid-term reported studies have documented encouraging 70 to 93% local tumor control rates, with minimal cerebral toxicity. Finally, during the last decade, GKR has become a primary treatment choice for patients harboring small-to-medium-size brain metastases, with reasonable life expectancy and no impending intracranial hypertension. Focal tumor responses are consistently elevated, even in the most radioresistant oncotypes (melanoma, renal carcinoma); median and actuarial survival rates are far better than with conventional radiation treatments and are comparable to those observed in accurately selected surgical-radiation series
Neuroradiosurgery and stereotactic radiotherapy. State of the art and future developments.
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Regional treatment of metastasis. Role of radiosurgery in brain metastases. Gamma Knife radiosurgery
No full textRadiosurgical treatment of cavernous sinus meningiomas: experience with 122 treated patients
No full textOBJECTIVE: To evaluate the efficacy of gamma knife (GK) radiosurgery, in terms of neurological improvement and tumor growth control (TGC), for a large series of patients with cavernous sinus meningiomas. METHODS: Between February 1993 and January 2002, 156 patients with cavernous sinus meningiomas (35 male and 121 female patients; mean age, 56.1 yr) were treated with GK radiosurgery in our department. GK radiosurgery was used as a first-choice treatment for 75 of 156 patients and as postoperative adjuvant therapy for 81 of 156 patients (all with Grade I meningiomas). Eligibility criteria for radiosurgery were as follows: symptomatic meningiomas and/or documented tumor progression on magnetic resonance imaging scans, conditions of high operative risk, patient refusal of microsurgery or reoperation, tumor volume of 4 yr), GK radiosurgery seems to be both safe (permanent morbidity rate, 1%) and effective (97% neurological improvement/stability, 97.5% overall TGC, and 96.5% actuarial TGC at 5 yr). GK radiosurgery might be considered a first-choice treatment for selected patients with cavernous sinus meningiomas
Analysis of long-term outcomes and prognostic factors in patients with non-small cell lung cancer brain metastases treated by gamma knife radiosurgery
No full textObject. The authors conducted a study to evaluate the long-term outcomes and prognostic factors for survival in a large series of patients treated by gamma knife surgery (GKS) for non—small cell lung cancer (NSCLC) brain metastases.
Methods. The study is based on the retrospective analysis of clinical and radiological records obtained during a 10-year period (1993–2003), concerning 836 lesions in 504 patients. The lesions were primary in 86% and recurrent 14% of the cases; they were solitary in 31%, single in 29%, and multiple in 40%. The mean follow-up period was 16 months (range 4–113 months). The most common histological types were adenocarcinoma (51%) and squamous cell carcinoma (27%). Dose planning parameters were as follows: mean target volume 6.2 cm3 (range 0.06–22.5 cm3); mean prescription dose 21.4 Gy (range 15.5–28 Gy); and mean number of isocenters 6.7 (range one–18). Progression-free and actuarial survival curves were calculated using the Kaplan—Meier method. The main factors affecting survival were determined by unimultivariate analysis (log-rank test and Cox proportional hazard models).
Analysis of long-term outcomes seemed to confirm that GKS is a primary therapeutic option in these patients. The 1-year local tumor control rate was 94%. The overall median survival was 14.5 months, with extremely rewarding quality of life indices. The recursive partitioning analysis classification was the dominant prognostic factor.
Conclusions. Gamma knife surgery is a useful treatment for brain metastases from NSCLC
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