Dosimetric comparison of ring and ovoid applicators.

PURPOSE: To compare the dosimetry of different vaginal applicators used in the postoperative vaginal cuff irradiation. MATERIALS AND METHODS: In this model dosimetric study, standard ovoid applicator sets with 3 cap sizes (small/15 mm, medium/20 mm, and large/25 mm), and ring applicator sets with 3 diameter sizes (small/26 mm, medium/30 mm, large/34 mm) each with 3 different angles (30, 45, and 60 degrees) were used. Calculations were performed in Plato TPS (Treatment Planning System) as dwell positions of 2.5 mm step and equal dwell time for the sources. For ovoid applicators, the source positions 1-5 were loaded as active on each catheter, and in ring applicators the source positions 1-12, and 18-29; 1-14, and 19-32; 1-17, and 22-37 were loaded for small, medium and large ones, respectively. In addition to ICRU rectum reference point (R(1)), 4 different rectum reference points (RP(s)) (R(2)-R(5)) were defined 1 cm apart. The vaginal cuff RP (V(c)) was defined at 5 mm depth from the vaginal surface. The reference volume dose distribution was obtained according to the V(c) (100%) reference point. The width (w), max-min length (h, h'), and max-min thickness (t, t') of the reference isodoses were measured and max-min reference volume (v, v') was calculated. RESULTS: R(1) dose was higher for ovoids (43.1%) than ring (28.6%), in all applicators. The increase of R(1) dose was parallel to the increase of ovoid/ring size (70-89%). As the applicator (ovoid-ring) size increased, max thickness of the reference isodose also increased (19-50%). For the largest size, the max increase was 62% (74.1-119.88 cm(3)) and 93% (59.15-114.24 cm(3)) for v and v', respectively. However, the magnitude of the reference volume was independent of the ring angle. CONCLUSION: In the present study it was found that when ring applicators were used according to recommended dwell positions, max rectum reference dose decreased in comparison to ovoid applicators; on the other hand, it should be noted that the size of the reference volume also decreased significantly.

Prognostic factors in limited-stage small cell lung cancer of patients treated with combined modality approach.

PURPOSE: To evaluate the combined modality treatment results of patients with limited-stage small cell lung cancer (SCLC), who were treated and followed by the DELCSG. PATIENTS AND METHODS: Sixty-three patients with limited-stage SCLC diagnosed between April 1991 and December 2002 were included. All patients were treated with combined chemotherapy and thoracic radiotherapy. Median age was 59 years (range 36-84), and all patients were male except 4. Surgery was performed for diagnosis in 3 patients. Four cycles of chemotherapy (median) were administered, composed of cisplatin-etoposide (CE) (26 patients), cyclophosphamide-vincristine-adriamycin (CAV) (10 patients) or alternated CE and CAV (18 patients). Nine patients received various chemotherapy regimes other than CE and/or CAV. A total dose of 5000 cGy with 180-200 cGy daily fractions was given to the primary tumor and mediastinum, excluding the spinal cord after 4500 cGy. Prophylactic cranial irradiation (PCI) was performed in 13 (20%) patients. Overall survival (OS) and progression-free survival (PFS) were calculated, beginning from the date of diagnosis and the end of radiotherapy, respectively. Kaplan-Meier method was used for obtaining survival rates. Log-rank test and Cox proportional hazards model were used for univariate and multivariate analyses, respectively. RESULTS: Median follow-up time was 17 months (range 3-131). Median PFS and OS were 12 (range 1-131) and 17 (range 3-131) months, respectively. Two-years PFS and OS rates were 27 % and 38 %, respectively. During follow-up, 27 (43%) patients developed brain metastasis; among them only 3 had received PCI. Univariate analysis showed that addition of PCI significantly improved PFS (p=0.025) and advanced age was a favorable prognostic factor for OS (p=0.039). In the multivariate analysis, advanced age (p=0.034) and addition of PCI (p=0.004) were independent factors increasing PFS, however no significant prognostic factor influencing OS was found. CONCLUSION: Our treatment results are in accordance with the relevant literature. It is also concluded that PCI should be given to all patients with complete response to chemotherapy. However, analysis of prognostic factors should be cautiously evaluated because of small number and heterogeneous distribution of patients in subgroups. Prospective studies are necessary for better determination of prognostic factors.

Prognostic significance of EGF receptor expression in early glottic cancer.

OBJECTIVE: A positive relationship between epidermal growth factor receptor (EGFR) expression and radioresistance has been shown both in vitro and in vivo. In a group of 31 patients with early glottic cancer treated with definitive radiotherapy, the relationship of EGFR expression with patient and tumor related parameters were analyzed and the prognostic effect of EGFR expression on local control (LC) was assessed. MATERIAL AND METHOD: Between 1991 and 2001, 114 patients with early glottic (Tis-T2N0M0) squamous cell carcinoma were treated with radiotherapy at our institution. Among these, 31 patients whose pretreatment pathology specimens were available for immunohistochemical analysis formed the study population. Median age was 64 (46-77). Anterior commissure involvement was evident in 12 (38.7%) patients. Distribution according to T stage was as follows: Tis 6 (19.3%), T1 22 (71%), and T2 3 (9.7%). Histopathological grades of the 25 T1-2 tumors were 10/25 (40%) grade 1, 9/25 (36%) grade 2 and 6/25 (24%) grade 3. Our radiotherapy regimen was 66-70 Gy in 33-35 fractions over 6.5-7 weeks. The median follow-up period was 45 months (range, 5-116). Following immunohistochemical staining, quantitative immunohistochemistry (IHC) was performed by image analysis software and stained tumoral area percentage (STAP) was identified. The cut-off value was < or =5% versus >5%. The relationship of EGFR expression with patient (age) and tumor related (T stage, histopathological grade, and anterior commissure involvement) parameters was evaluated using chi-square test. Prognostic significance of EGFR expression, age, T stage, histopathological grade, and anterior commissure involvement on LC was assessed using log-rank test. RESULTS: No difference was found in EGFR content distribution in relation to age, T stage, histopathological grade, and anterior commissure involvement. In the univariate analysis including age (< or =60 versus >60), T stage (Tis and T1 versus T2), histopathological grade (grade 1 and 2 versus grade 3), anterior commissure involvement (present versus absent), and EGFR expression (high versus low), only T stage and EGFR expression were found to be significant prognostic factors affecting LC (P = 0.0006 and P = 0.03, respectively). CONCLUSION: The results of this series support that EGFR expression is an unfavorable prognostic factor in early glottic carcinomas. For this reason EGFR IHC may be considered for selecting patients for more aggressive therapies (radiotherapy with different fractionation schemes or surgery) or enrollment into trials targeting EGFR signaling pathways.

Primary primitive neuro-ectodermal tumor of cauda equina with intracranial seeding.

Primitive neuro-ectodermal tumor (PNET) of the cauda equina is a rare entity. 18 cases have been reported in the literature so far, including 4 cases with intracranial seeding. Moreover parenchymal involvement of brain has never been reported as a form of intracranial seeding from PNET of the cauda equina. A 31 year-old female patient, with PNET of cauda equina showing intracranial seeding 6 months after surgery, is presented in this report. To our knowledge, this is the first adult case of spinal cord PNET with parenchymal involvement of brain. The histopathological, clinical and radiological findings as well as treatment of the patient were evaluated.

The role of radiotherapy in the management of diabetes insipidus caused by Langerhans cell histiocytosis.

Diabetes insipidus (DI) occurs in 5-50% of patients with a diagnosis of Langerhans cell histiocytosis (LCH). DI is the most common manifestation of central nervous system (CNS) involvement and is due to defects in the function of the posterior pituitary. Radiotherapy is recommended as early as possible after the diagnosis of DI, because response rates increase and the need for pitressin therapy may be obviated. The optimal period for radiotherapy seems to be less than one week. Generally, a total radiotherapy dose of 15-20 Gy or less is preferred. Further prospective studies are strongly needed to compare recurrence rates, late effects, disease course, and survival in treated and untreated groups.