1/17. Influence of dose calculation model on treatment plan evaluation in conformal radiotherapy: a three-case study.In modern conformal radiotherapy (CRT), we attempt to increase its therapeutic ratio, thus improving the survival chances and/or quality of life for patients. It is common to acknowledge that poor local tumor control or increased normal tissue complications may arise from inaccurate targeting of the tumor, failure to conform the high-dose distribution to the target volume, and inaccurately delivered radiation doses. A further cause for concern is the influence that errors or inaccuracies in the dose calculation may have on the management of radiation therapy. Such errors arise from inherent limitations in the calculation algorithm used, which are more significant in some anatomical sites than others. Furthermore, an estimate of the therapeutic ratio is given by the ratio of tumor control probability (TCP) and normal tissue complication probability (NTCP). The effectiveness of these predictive indicators also depends on the accuracy of the calculated dose distributions in the target and surrounding normal structures. In this work, we compared CRT dose distributions of plans for the treatment of prostate, head-and-neck, and lung tumors using the measurement-based Clarkson and model-based Superposition dose calculation algorithms. Dose-volume histograms (DVHs) for the planning target volume (PTV) and sensitive structures, as well as NTCP and TCP, were compared. Dose distributions, observed in the lung and head-and-neck plans, vary significantly with respect to dose conformity as a function of algorithm used. Differences in the calculated maximum dose of up to 14% were observed in the PTV and sensitive structures for the lung and head-and-neck Clarkson-based plans, respectively, compared to the Superposition-based plans. Furthermore, a difference in the biological outcomes of up to 14% in the NTCP and 4% in the TCP was noticed. The CRT plans show the importance of accurate modeling of the effect of tissue inhomogeneities on dose distributions in the target and critical structures for lung and head-and-neck treatments.- - - - - - - - - - ranking = 1keywords = probability (Clic here for more details about this article) |
2/17. paclitaxel-carboplatin induced radiation recall colitis.Some chemotherapeutic agents can "recall" the irradiated volumes by skin or pulmonary reactions in cancer patients who previously received radiation therapy. We report a recall colitis following the administration of paclitaxel-containing regimen in a patient who had been irradiated for a carcinoma of the uterine cervix. A 63-year-old woman underwent a Wertheim operation because of uterine cervix carcinoma. After 8 years of follow-up, a local recurrence was observed and she received curative external radiotherapy (45 Gy) to the pelvis. No significant adverse events were observed during the radiotherapy. Approximately one year later, she was hospitalized because of metastatic disease with multiple pulmonary nodules, and a chemotherapy regimen consisting of paclitaxel and carboplatin was administered. The day after the administration of chemotherapy the patient had diarrhea and rectal bleeding. Histological examination of the biopsy taken from rectal hyperemic lesions showed a radiation colitis. The symptoms reappeared after the administration of each course of chemotherapy and continued until the death of the patient despite the interruption of the chemotherapy. In conclusion, the probability of recall phenomena should be kept in mind in patients who received previously with pelvic radiotherapy and treated later with cytotoxic chemotherapy.- - - - - - - - - - ranking = 0.5keywords = probability (Clic here for more details about this article) |
3/17. The importance of clinical suspicion in diagnosing pulmonary embolism: a case of false-positive high probability radionuclide perfusion lung scan.The accuracy of scintigraphic evidence of perfusion defects, even when classified as 'high probability' by matching with ventilation techniques or thoracic roentenograms is unsatisfactory when used without a pre-test clinical evaluation of probability. Although unusual, a complete or near-complete unilateral absence of perfusion in a lung with normal perfusion controlaterally must alert clinicians to the possibility of a false-positive result. In such instances, the administration of therapeutic dosages of fibrinolitic and antithrombotic agents (or even surgery) may lead to deleterious consequences. We report a patient with malignancy causing extrinsic narrowing of the pulmonary artery leading to a drastic impairment in the perfusion of an entire lung, compatible with, but not diagnostic of massive pulmonary embolism.- - - - - - - - - - ranking = 3keywords = probability (Clic here for more details about this article) |
4/17. Extensive prolongation of aPTT with argatroban in an elderly patient with improving renal function, normal hepatic enzymes, and metastatic lung cancer.OBJECTIVE: To report a case of an elderly male with improving renal function and normal hepatic function who sustained an elevated activated partial thromboplastin time (aPTT) after an infusion of argatroban was discontinued. CASE SUMMARY: A 77-year-old white male with a history of heparin-induced thrombocytopenia (HIT) and metastatic lung disease was started on argatroban for treatment of a right upper-extremity deep vein thrombosis (DVT). The infusion was initiated at 2.0 microg/kg/min and was titrated to a goal aPTT of 60-80 seconds. Argatroban was discontinued due to an aPTT elevated to >100 seconds; the aPTT remained elevated for 130 hours after discontinuation of the infusion. DISCUSSION: Argatroban dose reductions in patients with impaired liver and renal function test values have been reported. Elderly subjects may have a prolonged clearance compared with young healthy subjects, although the duration of effect has not been established. As of April 18, 2005, the effect of liver metastasis on argatroban pharmacokinetics in the setting of normal liver function enzyme levels has not been reported. An objective causality assessment using the Naranjo probability scale showed that the prolonged aPTT was probably attributable to argatroban. CONCLUSIONS: Clinicians should exercise caution when initiating argatroban at a dose of 2.0 microg/kg/min in elderly patients with underlying comorbidities, such as metastatic disease and renal impairment, since this may lead to excessive and prolonged anticoagulation and increased risk of bleeding.- - - - - - - - - - ranking = 0.5keywords = probability (Clic here for more details about this article) |
5/17. Metastatic anaplastic carcinoma of the thyroid mimicking squamous cell carcinoma: report of a case of a challenging cytologic diagnosis.BACKGROUND: The probability of anaplastic transformation in a differentiated thyroid carcinoma (DTC) is <2%. Admixture of DTC and undifferentiated carcinoma can occasionally be found in thyroidectomy specimens, or the undifferentiated tumor may develop in metastatic foci months or years after removal of the primary tumor. CASE: Anaplastic transformation of a metastatic DTC was diagnosed at autopsy in a 71-year-old female. At the time of her total thyroidectomy for follicular carcinoma, she already had several lung nodules, which diminished in size upon 131I treatment. Five years later the patient developed a new, pleura-based lung mass. The mass extended along the paraspinal soft tissue and involved the kidney. Fine needle aspiration biopsy of the paraspinal mass resulted in a diagnosis of metastatic squamous cell carcinoma. Two months later the patient died. Histologic evaluation of the lung nodules and pleura-based mass revealed areas of follicular carcinoma intermixed with a various patterns of undifferentiated carcinoma. The paraspinal and kidney mass consisted entirely of anaplastic tumor, including areas of squamoid differentiation. CONCLUSION: In patients with a history of DTC who develop a rapidly growing mass elsewhere, a possibility of metastatic DTC with anaplastic transformation must be considered.- - - - - - - - - - ranking = 0.5keywords = probability (Clic here for more details about this article) |
6/17. Rheumatologic manifestations of malignancy.The relationship between rheumatologic syndromes and cancer covers a very broad array of both common and distinctly rare manifestations. This discussion has outlined some of the known relationships that do exist. A high index of suspicion by both the primary care physician and subspecialist will enhance the probability of detecting cancer in the patient who may present with rheumatologic complaints.- - - - - - - - - - ranking = 0.5keywords = probability (Clic here for more details about this article) |
7/17. cobalt-57 bleomycin scanning for lung cancer detection: a prospective study in thoracic surgery.patients displaying an abnormal chest X-ray, in some cases, cause a difficult diagnostic problem. A differential diagnosis between benign and malignant lesions is important to determine the choice of treatment i.e. whether or not to perform a thoracotomy. In a prospective study, we have examined the role of 57Co-bleomycin scanning for prethoracotomy assessment of 60 patients with a high clinical probability of lung cancer. For these patients, a sensitivity of 89%, a specificity of 84% and an accuracy of 88% were found. However, as a consequence of the six false-negative scans (two in-situ carcinomas and four stage I carcinomas), bleomycin scanning cannot be regarded as adequate for obviating thoracotomy in patients with a high clinical probability of lung cancer but a negative scan. Nevertheless, the technique is useful for the assessment of tumour size and for the detection of hilar, mediastinal and extra-thoracic metastases, with consequences for TNM staging. It has been found that the tumour dimension correlates well with the actual anatomo-pathologic size determined after surgical examination (r2 = 0.65 and p less than 0.01). Therefore, with an accuracy around 90% for the diagnosis of lung cancer, 57Co-bleomycin scanning offers a major tool for use in clinical investigation.- - - - - - - - - - ranking = 1keywords = probability (Clic here for more details about this article) |
8/17. Primary duodenal carcinoma arising in a non-vaterian tubulo-villous adenoma. A case report with immunocytochemical analysis and review of the literature.Primary duodenal carcinoma and duodenal adenoma are rare tumours. Duodenal carcinoma makes up about 0.3% of all malignant tumours of the gastrointestinal tract (Alwmark et al. 1980; Spira et al. 1977). The present paper describes a duodenal carcinoma arising in a mixed tubulo-villous non-Vaterian adenoma in a 68 year old male. Immunocytochemical analysis revealed evidence of neuroendocrine differentiation in both adenoma and carcinoma. In a review of the literature a correlation between the size of adenoma and the probability of concomitant carcinoma is demonstrated. Duodenal adenoma measuring more than 4 cm in diameter should be considered potentially malignant.- - - - - - - - - - ranking = 0.5keywords = probability (Clic here for more details about this article) |
9/17. Acute nonlymphocytic leukemia after treatment of small cell lung cancer.From 1977 to 1982, 377 patients with small cell lung cancer were treated at Vanderbilt University Medical Center. All patients received combination chemotherapy consisting of cyclophosphamide, doxorubicin, and vincristine (CAV) with or without methotrexate, etoposide, and/or hexamethylmelamine. Thoracic and/or prophylactic cranial irradiation was administered to 159 (42 percent) and 192 (51 percent) patients, respectively. Acute nonlymphocytic leukemia was observed in two patients at 22 and 81 months from the start of therapy. The relative risk of leukemia was 154 (95 percent confidence limit, 38 to 293). A kaplan-meier estimate of the cumulative probability of leukemia was 1.9 /- 1.4 percent seven years after the start of treatment. The relative risk of leukemia is significantly increased in this group of patients (p less than 0.0001). Acute nonlymphocytic leukemia is a long-term complication of small cell lung cancer therapy.- - - - - - - - - - ranking = 0.5keywords = probability (Clic here for more details about this article) |
10/17. The triad of gastric epithelioid leiomyosarcoma, functioning extra-adrenal paraganglioma, and pulmonary chondroma.The triad of gastric epithelioid leiomyosarcoma, functioning extra-adrenal paraganglioma, and pulmonary chondroma was found in two young female Mayo Clinic patients, and two of these tumors occurred in another two. review of the world literature disclosed nine patients who probably had two or more of the three neoplasms. We are also aware of two other patients with two of the three tumors. The association of gastric epitheloid leiomyosarcoma, functioning extra-adrenal paraganglioma, and pulmonary chondroma may well constitute a syndrome because of 1) the improbability of the coincidental occurrence of this triad of tumors, 2) the multicentricity of the tumors in the organs or system affected, and 3) the development of the tumors at a young age. Because two of the components of the triad are potentially lethal, it is important that patients less than 35 years of age who have any one of the three tumors be examined periodically to search for the others.- - - - - - - - - - ranking = 0.5keywords = probability (Clic here for more details about this article) |
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