1/9. Absence of multiple local minima effects in intensity modulated optimization with dose-volume constraints.This paper reports on the analysis of intensity modulated radiation treatment optimization problems in the presence of non-convex feasible parameter spaces caused by the specification of dose-volume constraints for the organs-at-risk (OARs). The main aim was to determine whether the presence of those non-convex spaces affects the optimization of clinical cases in any significant way. This was done in two phases: (1) Using a carefully designed two-dimensional mathematical phantom that exhibits two controllable minima and with randomly initialized beamlet weights, we developed a methodology for exploring the nature of the convergence characteristics of quadratic cost function optimizations (deterministic or stochastic). The methodology is based on observing the statistical behaviour of the residual cost at the end of optimizations in which the stopping criterion is progressively more demanding and carrying out those optimizations to very small error changes per iteration. (2) Seven clinical cases were then analysed with dose-volume constraints that are stronger than originally used in the clinic. The clinical cases are two prostate cases differently posed, a meningioma case, two head-and-neck cases, a spleen case and a spine case. Of the 14 different sets of optimizations (with and without the specification of maximum doses allowed for the OARs), 12 fail to show any effect due to the existence of non-convex feasible spaces. The remaining two sets of optimizations show evidence of multiple minima in the solutions, but those minima are very close to each other in cost and the resulting treatment plans are practically identical, as measured by the quality of the dose-volume histograms (DVHs). We discuss the differences between fluence maps resulting from those similar treatment plans. We provide a possible reason for the observed results and conclude that, although the study is necessarily limited, the annealing characteristics of a simulated annealing method may not be justified in clinical optimization in the presence of dose-volume constraints. The results of optimizations by the Newton gradient (NG) method with a quadratic cost function are reported in detail. An adaptive simulated annealing method, optimizing the same function, and the dynamically penalized likelihood method, optimizing a log likelihood function, have also been used in the study. The results of the latter two methods have only been discussed briefly, as they yielded the same conclusions as the NG method.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
2/9. Primary and pure neuroendocrine tumor of the prostate.Primary neuroendocrine tumors of the prostate are very rare and their biologic behaviour is not yet well known. Clinical and histopathologic features of two cases, one with lymph-node involvement and one organ-confined are described. Young age, clinical presentation and good outcome after radical retropubic prostatectomy were comparable in both patients.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
3/9. Simultaneous tumour-like, atypical basal cell hyperplasia and acinar adenocarcinoma of the prostate: a comparative morphological and genetic approach.Basal cell tumours of the prostatic gland are rare, and the classification is difficult. In the present case report, a large, tumour-like proliferation of atypical basaloid cells was found incidentally in a prostatectomy specimen that otherwise contained a conventional acinar adenocarcinoma. The basaloid cells displayed a solid or adenoid-cystic growth pattern and strongly expressed high-molecular-weight cytokeratins and bcl-2. A high Ki-67 index was recorded within the atypical basaloid cells, by far exceeding the one counted in the conventional adenocarcinoma. However, there were no definite criteria for a malignant behaviour of the basal cell tumour. Comparative genomic hybridisation from microdissected tumour cells yielded losses at the short arms of chromosomes 8 and 12 in the conventional adenocarcinoma and a normal karyotype in the basal cell tumour. The pathological findings favoured the diagnosis of an atypical basal cell hyperplasia.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
4/9. natural history and prognosis of prostate carcinoma in adolescents and men under 35 years of age.Prostate cancer is extremely rare in men under 35 years of age. The tumour is invariably poorly differentiated and aggressive, with rapidly growing bulky soft tissue metastases and negative tumour markers. Bone metastases develop late and are usually osteolytic. The disease responds poorly to radiation or hormonal therapy and is too advanced at presentation for radical surgery. Chemotherapy appears to be of some benefit, though in the majority of cases death occurs within a year. We describe a 31-year-old man with carcinoma of the prostate. A review of the literature is presented. This is the first patient in whom the epithelial origin of the prostate cancer was confirmed by immunoperoxidase staining with prostatic specific antigen. plasma prostatic specific antigen was normal despite a large tumour burden and widespread metastases. He did not respond to conventional treatment. The phenotypic expression and biological behaviour of these tumours are distinct from those occurring in men beyond the fourth decade.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
5/9. Anticipatory nausea and vomiting: a form of chemotherapy phobia?This paper proposes that the phenomenon of anticipatory nausea and/or vomiting is a component of a phobic response to chemotherapy. Two cases are presented to highlight the clinical aspects of chemotherapy phobia. The evidence confirming such a diagnosis is put forth as it relates to anticipatory anxiety, phobic response, avoidance behaviour and treatment.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
6/9. Massive prostatic carcinoma in negroes.Three cases of massive carcinoma of the prostate in negroes are presented. Investigation and treatment were carried out along conventional lines. There was a very good response to treatment initially in that all tumours shrank and became impalpable. Two patients died of recurrent carcinoma at 1 and 2 3/4 years respectively. The third has widespread metastases at present controlled by chemotherapy. The possible differences in the behaviour of prostatic carcinoma in negroes are discussed.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
7/9. Imaging of small cell carcinoma of the male urogenital tract.Five cases of small cell carcinoma (three of the prostate and two of the bladder) are described to illustrate the unusual behaviour of these tumours. Cerebral, hepatic and bulky lymph node spread with large volume local disease occurred. The role the radiologist may play in these diseases is discussed.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
8/9. Ki-67 expression in early prostate cancer and associated pathological lesions.AIM: To assess cell proliferation in early prostate cancer and associated pathological lesions. methods: Using the Ki-67 antibody, the cell proliferation index was measured in early stage prostatic carcinoma in 37 incidental tumours diagnosed at transurethral prostatectomy (TURP) and in 20 low volume cancers treated by radical prostatectomy. Proliferation indexes have also been measured in areas of normal peripheral zone, transition zone hyperplasia, atrophic appearing lobules, and high grade prostatic intraepithelial neoplasia in the radical prostatectomy cases. RESULTS: In the TURP series the proliferation index correlated with grade and stage. Logistic regression analysis, however, showed that Gleason grade was the most reliable predictor of biopsy proven residual disease and clinical progression. In the radical series transition zone carcinoma the proliferation index was half that of peripheral zone carcinoma. The atrophic lobules also showed a high proliferation index of the same order as seen in the peripheral zone carcinoma. Normal peripheral zone showed the lowest proliferation index and in hyperplastic transition zone it was also less than the other areas. CONCLUSIONS: There is only limited support for the correlation of proliferation index with grade in early stage prostatic carcinoma. The findings do not suggest that proliferation index adds to the prognostic information given by grade and stage in pT1 disease. The significant difference in proliferation index in transition zone and peripheral zone carcinomas supports the morphological distinction of these tumour types and is consistent with differences in biological behaviour. The high proliferation index in lobules considered morphologically atrophic is reminiscent of previous observations in which carcinoma was spatially associated with atrophy.- - - - - - - - - - ranking = 1keywords = behaviour (Clic here for more details about this article) |
9/9. Indolent behaviour of low-grade B-cell lymphoma of mucosa-associated lymphoid tissue involved in salivary glands, renal sinus and prostate.We report a case of MALT lymphoma (malignant lymphoma of mucosa-associated lymphoid tissues) involved in the salivary glands, the renal sinus and the prostate. The masses have been progressing very slowly and the patient has remained alive without any treatment for 5 years from the first symptom of this disease.- - - - - - - - - - ranking = 4keywords = behaviour (Clic here for more details about this article) |