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.

Is re-irradiation effective in symptomatic local recurrence of non small cell lung cancer patients? A single institution experience and review of the literature.

PURPOSE: To determine reirradiation results of patients with recurrent non-metastatic non-small cell lung cancer (NSCLC). PATIENTS AND METHODS: 38 NSCLC patients who showed clinical and/or radiological progression and were retreated with hypofractionated irradiation (RT) were retrospectively evaluated. Two parallel or oblique opposed fields were used for reirradiation of the recurrent tumor while excluding the spinal cord. "Improvement" and "complete or near complete response" were defined as > or = 50% and 75-100% regression of symptoms, respectively. Log-rank test, chi-square test and Cox regression analysis were used for statistical analyses. RESULTS: Median age was 58 years (range 33-80) and only 3 patients were females. Median follow-up was 13.5 months (range 4-65). In the initial and second course of RT the total dose was 30 Gy (range 28.8-67.2) and 25 Gy (range 5-30) and the number of fractions was 10 (range 9-33) and 10 (range 1-10), respectively. The median interval between the two RT courses was 35 weeks (range 4-189). After reirradiation improvement was observed in 86% of the patients assessable for hemoptysis, in 77% with cough, in 69% with dyspnea, and in 60% with thoracic pain. After reirradiation, the median survival time was 3 months (range 0-55). Two-year survival rates from diagnosis were 28.8% and from reirradiation 5.8%. An interval more than 35 weeks between the end of initial RT and the start of reirradiation was found as the only independent prognostic factor affecting survival. No grade III-IV RTOG late side effects were observed. CONCLUSION: In initially non-metastatic NSCLC patients, reirradiation can be a safe and effective treatment for palliation after recurrence. Large prospective studies are needed to confirm the safety, effectiveness and economical advantages of this modality.

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.

Optimization in high dose rate brachytherapy for utero-vaginal applications.

BACKGROUND AND PURPOSE: High dose rate (HDR) remote afterloading intracavitary brachytherapy is an effective treatment modality which has some advantages over low dose rate (LDR) techniques for gynaecological cancer. Optimization is one of the possibilities of modern brachytherapy techniques, especially the stepping source technology. The use of the term 'optimization' implies achieving the desired optimum dose distribution by changing some parameters of the treatment. The aim of this study was to theoretically evaluate the optimization possibilities by modifying dwell times and dwell positions of the uterine and vaginal sources. MATERIALS AND METHODS: Working on a virtual utero-vaginal model, the dose distribution variations in the rectum, bladder, mean point B reference points and volume parameters were investigated whilst giving a standard dose to point A in the Manchester system. In this model, the intrauterine tandem consisted of 27 dwell positions for 2.5 mm steps and 14 dwell positions for 5 mm steps. Vaginal colpostats consisted of five dwell positions each for 2.5 mm steps. Using a Nucletron Plato treatment planning system and a Microselectron Ir-192 HDR stepping source unit, the dwell times of the intrauterine (T(u)) and vaginal sources (T(v)) were modified at the ratios of (T(u)/T(v)) 1:1; 1:2; 1:3; 1:4; 1:0.50; 1:0.33; and 1:0.25 for the two different dwell positions, 2.5 and 5 mm steps, of the intrauterine tandem. RESULTS: All evaluated parameters decreased with increasing dwell time ratios of uterine tandem to vaginal colpostats, with the greatest fall in the percentage of rectum reference dose (D(R) %), 23 and 28% for 2.5 and 5 mm dwell positions respectively; in addition, the reference isodose volume decreased by 14 and 17% for 2.5 and 5 mm dwell positions, respectively. All evaluated parameters increased with decreasing dwell time ratios of uterine tandem to vaginal colpostats for both dwell positions. The DR% of 1:1-1:4 (T(u)/T(v)) weightings showed an increase from 40.6 to 58.3 (44%) for 2.5 mm and from 49.2 to 67.5 (37%) for 5 mm dwell positions. The volume was increased by 27 and 37% for 2.5 and 5 mm dwell positions respectively. CONCLUSION: Modern brachytherapy techniques enable the individualization of treatments by optimization procedures in gynaecological brachytherapy applications. By altering the dwell time and position, some important changes in reference points, volume and treatment time can be achieved, whilst maintaining a standard dose to point A.

The role of palliative radiotherapy in locally advanced non-small cell lung cancer.

The aim of this study was to evaluate retrospectively the treatment results of non-small cell lung cancer (NSCLC) patients treated with palliative intent in Dokuz Eylul University Hospital, Radiation Oncology Department. One hundred and fifteen inoperable, non-metastatic and symptomatic NSCLC patients were treated with palliative radiotherapy (PRT) between July 1991 and May 2000. PRT was used in patients with low performance status, weight loss more than 10% within last 6 months, secondary malignancies, co-morbid diseases and socio-economic problems. Parallelly opposed isocentric antero-posterior fields including both the parenchymal and mediastinal masses were used. 10-55 Gy total doses were delivered in 1-23 fractions with a median of 30 Gy. Nineteen patients received systemic chemotherapy before PRT. Survival analysis was made from the treatment beginning date, and subjective palliation rates were assessed according to clinical improvements in symptomatology evaluated 1-6 weeks after PRT. The median follow-up time was 28 weeks (1-234 weeks). Totally, 245 disease-related symptoms were detected in 115 patients. Overall "improvement" in symptomatology was found to be 90% (221/245) with a "near-total response" rate of 46% (113/245). Hemoptysis was the best palliated symptom. Median survival time was 30 weeks. Karnofsky performance status (KPS) (p=0.015), weight loss (p=0.0015), histologic tumor type (p=0.0024) and tumor size (p=0.02) were found to effect overall survival rates significantly in uni-variant analysis. Multi-variant analysis revealed statistically significant effect with histological tumor type and weight loss status. Only 16% of patients (3/19) showed partial and 5% (1/19) complete response to systemic treatment. Median survival time was 46 weeks in this group. In conclusion, this retrospective study of patients with poor prognostic factors confirms that PRT is an effective treatment modality in symptomatic locally advanced NSCLC patients resulting in 90% symptomatic improvement rate and a median survival of 30 weeks.

Tc-99m MDP, thallium-201 chloride and Tc-99m MAG3 renal uptake in subacute and chronic radiation nephritis compared.

The authors present a comparison of the findings for thallium-201 (Tl-201), Tc-99m MAG3 and Tc-99m MDP in subacute and chronic radiation nephritis in a 9-yr-old boy who was treated by radiation therapy for alveolar rhabdomyosarcoma of the left chest wall by a radiation port that partially included the left kidney. Tl-201 imaging three and six months later showed a cortical defect in the left kidney due to radiation nephritis. Tc-99m MDP scan showed increased uptake on both occasions, but more marked in the subacute period than in the chronic period. Tc-99m MAG3 showed decreased concentration and increased cortical retention three months later. Six months after the radiation therapy, a cortical defect corresponding to the cortical area that showed increased parenchymal retention was more prominent in the Tc-99m MAG3 scan. In the present case, Tc-99m MDP, Tl-201 and Tc-99m MAG3 findings may provide useful information for understanding pathophysiological damage in the kidney after radiation.

Prognostic factors in lung cancer with brain metastasis.

BACKGROUND AND PURPOSE: Metastasis to the brain develops in 25% of all patients with lung cancer. Although the outcome is usually poor, there seems to be a subset of patients with favorable prognostic factors who may live longer. Prognostic factors were analyzed retrospectively in 103 patients with brain metastases from lung carcinoma to identify patients who would benefit from more intensive treatment strategies. MATERIALS AND METHODS: Between October 1991 and December 1994, 103 patients with brain metastasis from lung cancer were irradiated with palliative intent. Palliation was defined as 50% or more regression of neurological signs and symptoms 2 weeks after the completion of cranial radiotherapy. Local (related to the lung tumor) symptom status at the time of brain metastasis, the presence of metastases other than brain, multiplicity of brain metastases on CT scan and time of occurrence of brain metastasis were the factors which were evaluated with multivariate analysis. RESULTS: Palliation was accomplished in 85% of cases. Palliation duration ranged from 0.5 to 54 months (median 3 months). The overall median survival was 5 months. Only one patient is under follow-up without any symptoms related to the brain metastasis. According to the multivariate analysis survival was significantly decreased in the presence of symptoms related to the primary tumor (P = 0.001). CONCLUSION: The presence of symptoms related to the primary tumor at the time of brain metastasis is one of the factors that can be used to distinguish patients with a favorable outcome. In patients with favorable prognostic factors and thus longer survival probability, the role of boost dose after whole brain radiotherapy or surgical resection in suitable cases needs to be investigated.

Iridium-192 versus cobalt-60 boost in 3-7 cm breast cancer treated by irradiation alone: final results of a randomized trial.

This prospective randomized trial compared an iridium-192 implant boost with a cobalt-60 external irradiation boost to the primary tumor site, in 255 patients with breast cancers 3-7 cm in diameter. All patients had a partial (> 50%) or complete response following primary external beam irradiation of 58 Gy to the whole breast, as well as irradiation to the axillary, supraclavicular and internal mammary nodes. Patients with clinically positive axillary nodes also received a cobalt-60 10-15 Gy boost to the inferior axilla. All patients had core biopsy only. Both groups were comparable in age, tumor size, node involvement, grade, and progesterone receptor levels. The boost dose was 20 Gy in both groups. At the median 8-year follow-up, the breast recurrence risk was 24% in the iridium group and 39% in the cobalt group (p = 0.02). When adjusted to other prognostic and treatment factors, the brachytherapy boost decreased the breast recurrence risk by 60%. The 8-year breast preservation rates were 81% and 67%, respectively (p = 0.024). Cosmetic outcome in both groups was evaluated in 120 patients with a minimum 3-year follow-up and was comparable in both groups. This study demonstrates that in selected patients with large tumors treated with irradiation alone, local control and breast preservation rates are improved by the use of brachytherapy to boost the primary tumor.