Asymptotic behaviour of estimators of the parameters of nearly unstable INAR(1) models

A sequence of first-order integer-valued autoregressive type (INAR(1)) processes is investigated, where the autoregressive type coefficients converge to 1. It is shown that the limiting distribution of the joint conditional least squares estimators for this coefficient and for the mean of the innovation is normal. Consequences for sequences of Galton{Watson branching processes with unobservable immigration, where the mean of the offspring distribution converges to 1 (which is the critical value), are discussed

Plasma Bmil mRNA as a potential prognostic biomarker for distant metastasis in colorectal cancer patients

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Radical radiotherapy for nasopharyngeal carcinoma in elderly patients: The importance of co-morbidity assessment

Elderly patients represent a unique challenge for radical treatment in nasopharyngeal carcinoma (NPC) because of age and co-morbid conditions. We sought to evaluate the outcome of this particular group of patients and to identify key factors affecting treatment outcome. From 1998 to 2008, 990 consecutive NPC patients without distant metastasis were treated with radical radiotherapy with planned total dose >66 Gy. Among them, 103 (10.4%) patients were elderly aged >70 (group A). Their clinical characteristics and outcome were compared with those aged <70 (group B). Mortality at 90 days was used as a proxy of early deaths related to treatment. Co-morbidities were measured by the Adult Co-morbidity Evaluation 27 (ACE-27). Group A presented more commonly with poorer performance status. They showed higher rates of acute reaction, radiotherapy incompletion and mortality at 90 days (7.8% vs. 1.2%, p < 0.001). The 5-year overall survival rates were 43.9% and 78.1% for groups A and B, respectively (p < 0.001). No difference in failure free survival rates was noted. For group A, ACE-27 was the only predicting factor for mortality at 90 days [ACE-27 2-3 vs. 0-1: HR 15.86 (2.68-93.95), p = 0.002], and the most important prognostic factors for overall survival included age, presenting stage and ACE-27 (p < 0.05). Elderly NPC patients had poorer tolerance to radiotherapy. Early deaths related to treatment were not uncommon. A reasonable disease control can still be attained after radical radiotherapy for those who were able to survive through the peri-radiotherapy period. Patient selection and treatment approach with reference to ACE-27 should be considered. © 2011 Elsevier Ltd. All rights reserved.link_to_subscribed_fulltex

Management of nasopharyngeal carcinoma

Nasopharyngeal carcinoma is a distinctly radiosensitive and chemosensitive tumor. Best quality radiotherapy is demanded to build up the complex concave high-dose zone for this critical location. Intensity-modulated radiotherapy (IMRT) is advocated; image guidance to ensure setup precision and adaptive re-planning if major deviations from intended dose distribution occur during the treatment course are useful improvements if resources allow. Stringent dose constraint to organs at risk should be attempted to minimize late toxicities. Addition of cisplatin-based concurrent-adjuvant chemotherapy is recommended for patients with stages III–IVB and high-risk stage IIB diseases. Contemporary series using IMRT together with extensive use of chemotherapy reported very encouraging long-term results with locoregional control in excess of 85 % at 5 years; the key remaining problems are advanced T4 disease and distant failure. Further improvement of efficacy by more potent systemic therapy and changing chemotherapy sequence to induction-concurrent is being explored. The plasma level of Epstein–Barr Viral Deoxyribonucleic Acid is a well-established tool for non-keratinizing carcinoma for prognostication and monitoring disease progress. Integrated fluorodeoxyglucose positron emission tomography and computed tomography is useful for excluding distant metastases and posttreatment persistent/recurrent disease. Early detection of failure is critical; and aggressive treatment should be attempted as long survival could be achieved for patients with limited failure. Different salvage methods and reported results are summarized