Second malignant neoplasms (SMNs) and cardiovascular disease (CVD) are among the most serious and life-threatening late adverse effects experienced by the growing number of cancer survivors worldwide ...and are due in part to radiotherapy. The National Council on Radiation Protection and Measurements (NCRP) convened an expert scientific committee to critically and comprehensively review associations between radiotherapy and SMNs and CVD, taking into account radiobiology; genomics; treatment (ie, radiotherapy with or without chemotherapy and other therapies); type of radiation; and quantitative considerations (ie, dose-response relationships). Major conclusions of the NCRP include: 1) the relevance of older technologies for current risk assessment when organ-specific absorbed dose and the appropriate relative biological effectiveness are taken into account and 2) the identification of critical research needs with regard to newer radiation modalities, dose-response relationships, and genetic susceptibility. Recommendation for research priorities and infrastructural requirements include 1) long-term large-scale follow-up of extant cancer survivors and prospectively treated patients to characterize risks of SMNs and CVD in terms of radiation dose and type; 2) biological sample collection to integrate epidemiological studies with molecular and genetic evaluations; 3) investigation of interactions between radiotherapy and other potential confounding factors, such as age, sex, race, tobacco and alcohol use, dietary intake, energy balance, and other cofactors, as well as genetic susceptibility; 4) focusing on adolescent and young adult cancer survivors, given the sparse research in this population; and 5) construction of comprehensive risk prediction models for SMNs and CVD to permit the development of follow-up guidelines and prevention and intervention strategies.
Radiation therapy treatment planning and delivery capabilities have changed dramatically since the introduction of three-dimensional treatment planning and are continuing to change relatively rapidly ...in response to the implementation of new advanced technologies. Three-dimensional conformal radiation therapy (3DCRT) is now firmly in place as the standard of practice in clinics around the world. Medical accelerator manufacturers have employed advanced computer technology to produce treatment planning/delivery systems capable of precise shaping of dose distributions via computer-controlled multileaf collimator (MLC) systems, by which the beam fluence is varied optimally to achieve the desired dose distribution. This mode of conformal therapy is referred to as intensity modulated radiation therapy (IMRT), and is capable of generating dose distributions (including concave isodose volumes) that closely conform the prescription dose to the target volume and/or avoid specific sensitive normal structures. The increasing use of IMRT has focused attention on the need to better account for the intra- and inter-fraction spatial uncertainties in the dose delivery process. This has helped spur the development of treatment machines with integrated planar and volumetric advanced imaging capabilities, providing a new treatment modality referred to as image-guided IMRT (IG-IMRT), or simply image-guided radiation therapy (IGRT). In addition, there is a growing interest in replacing x rays with protons because of the physical characteristics of the depth dose curve, which peaks at the end of particle range, and eventually with even heavier charged particles to take advantage of the greater density of energy deposition close to the Bragg peak and hence larger relative biological effectiveness (RBE). Three-dimensional CRT, IMRT and proton beam therapy all provide improved target coverage and lower doses to surrounding normal tissues as compared to the previously used two-dimensional radiation therapy techniques. However, this is achieved at the expense of a greater volume of normal tissue in the irradiated volume receiving some dose and a higher whole body dose (or peripheral dose) to distant normal tissues. The higher whole body dose is a result of the increased x-ray leakage radiation to the patient due to the longer beam-on times associated with IMRT, and also from neutron leakage radiation associated with high energy x-ray beams (>10 MV) and proton beams. Dose distributions for the various CRT techniques and the current status of available data for normal tissues, and whole body dose are reviewed.
Through sharing results of an analysis of design language use in several writing studies journals, this article explores why we invoke design in published scholarship. After defining the approach to ...composing known as design thinking, it then moves to a comparison of design thinking and the writing process and looks at an example application of design thinking in the field. I argue that design thinking not only offers a useful approach for tackling multimodal/multimedia composing tasks, but also situates the goal of writing studies as textual action and asks us to reconsider writing's home in the university.
Full text
Available for:
BFBNIB, NMLJ, NUK, PNG, SAZU, UL, UM, UPUK, ZRSKP
To determine the effect of prophylactic gastrostomy tube (GT) placement on acute and long-term outcome for patients treated with definitive chemoradiotherapy for locally advanced head and neck ...cancer.
One hundred twenty consecutive patients were treated with chemoradiotherapy for Stage III/IV head and neck cancer to a median dose of 70 Gy (range, 64-74 Gy). The most common primary site was the oropharynx (66 patients). Sixty-seven patients (56%) were treated using intensity-modulated radiotherapy (IMRT). Seventy patients (58%) received prophylactic GT placement at the discretion of the physician before initiation of chemoradiotherapy.
Prophylactic GT placement significantly reduced weight loss during radiation therapy from 43 pounds (range, 0 to 76 pounds) to 19 pounds (range, 0 to 51 pounds), which corresponded to a net change of -14% (range, 0% to -30%) and -8% (range, +1% to -22%) from baseline, respectively (p < 0.001). However, the proportion of patients who were GT-dependent at 6- and 12-months after treatment was 41% and 21%, respectively, compared with 8% and 0%, respectively, for those with and without prophylactic GT (p < 0.001). Additionally, prophylactic GT was associated with a significantly higher incidence of late esophageal stricture compared with those who did not have prophylactic GT (30% vs. 6%, p < 0.001).
Although prophylactic GT placement was effective at preventing acute weight loss and the need for intravenous hydration, it was also associated with significantly higher rates of late esophageal toxicity. The benefits of this strategy must be balanced with the risks.
Full text
Available for:
GEOZS, IJS, NUK, OILJ, UL, UM, UPUK
Purdy reviews Nostalgic Design: Rhetoric, Memory, and Democratizing Technology by William C. Kurlinkus, Sounding Composition: Multimodal Pedagogies for Embodied Listening by Steph Ceraso, Update ...Culture and the Afterlife of Digital Writing by John R. Gallagher and Rhet Ops: Rhetoric and Information Warfare edited by Jim Ridolfo and William Hart-Davidson.
To evaluate the effect of continued cigarette smoking among patients undergoing radiation therapy for head-and-neck cancer by comparing the clinical outcomes among active smokers and quitters.
A ...review of medical records identified 101 patients with newly diagnosed squamous cell carcinoma of the head and neck who continued to smoke during radiation therapy. Each active smoker was matched to a control patient who had quit smoking before initiation of radiation therapy. Matching was based on tobacco history (pack-years), primary site, age, sex, Karnofsky Performance Status, disease stage, radiation dose, chemotherapy use, year of treatment, and whether surgical resection was performed. Outcomes were compared by use of Kaplan-Meier analysis. Normal tissue effects were graded according to the Radiation Therapy Oncology Group/European Organization for the Treatment of Cancer toxicity criteria.
With a median follow-up of 49 months, active smokers had significantly inferior 5-year overall survival (23% vs. 55%), locoregional control (58% vs. 69%), and disease-free survival (42% vs. 65%) compared with the former smokers who had quit before radiation therapy (p < 0.05 for all). These differences remained statistically significant when patients treated by postoperative or definitive radiation therapy were analyzed separately. The incidence of Grade 3 or greater late complications was also significantly increased among active smokers compared with former smokers (49% vs. 31%, p = 0.01).
Tobacco smoking during radiation therapy for head-and-neck cancer is associated with unfavorable outcomes. Further studies analyzing the biologic and molecular reasons underlying these differences are planned.
Full text
Available for:
GEOZS, IJS, NUK, OILJ, UL, UM, UPUK
To estimate α/β, the parameter ratio from the linear-quadratic (LQ) model, for Grade ≥2 late rectal toxicity among patients treated on Radiation Therapy Oncology Group (RTOG) protocol 94-06; and to ...determine whether correcting the rectal dose-volume histogram (DVH) for differences in dose per fraction, based on the LQ model, significantly improves the fit to these data of the Lyman-Kutcher-Burman (LKB) normal-tissue complication probability (NTCP) model.
The generalized LKB model was fitted to the Grade ≥2 late rectal toxicity data in two ways: by using DVHs representing physical dose to rectum, and by using a modified approach in which dose bins in the rectal DVH were corrected for differences in dose per fraction using the LQ model, with α/β estimated as an additional unknown parameter. The analysis included only patients treated with the same treatment plan throughout radiotherapy, so that the dose per fraction to each voxel of rectum could be determined from the DVH. The likelihood ratio test was used to assess whether the fit of the LQ-corrected model was significantly better than the fit of the LKB model based on physical doses to rectum.
The analysis included 509 of the 1,084 patients enrolled on RTOG 94-06. The estimate of α/β from the LQ-corrected LKB model was 4.8 Gy, with 68% confidence interval 0.6 Gy to 46 Gy. The fit was not significantly different from the fit of the LKB model based on physical dose to rectum (p = 0.236).
The estimated fractionation sensitivity for Grade ≥2 late rectal toxicity is consistent with values of α/β for rectum found previously in human beings and in rodents. However, the confidence interval is large, and there is no evidence that LQ correction of the rectal DVH significantly changes the fit or predictions of the LKB model for this endpoint.
Full text
Available for:
GEOZS, IJS, NUK, OILJ, UL, UM, UPUK
Phase I of Radiation Therapy Oncology Group (RTOG) 0117 determined that 74 Gy was the maximum-tolerated dose with concurrent weekly carboplatin/paclitaxel chemotherapy for inoperable non-small-cell ...lung cancer (NSCLC). Phase II results are reported here. PATIENTS AND METHODS Patients with unresectable stages I-III NSCLC were eligible. Chemotherapy consisted of weekly paclitaxel at 50 mg/m(2) and carboplatin at area under the curve 2 mg/m(2). The radiation dose was 74 Gy given in 37 fractions. Radiation therapy volumes included those of the gross tumor and involved nodes. The volume of lung at or exceeding 20 Gy (V20) was mandated to be <or= 30%.
Of the combined phase I/II enrollment, a total of 55 patients received 74 Gy, of whom 53 were evaluable. The median follow-up was 19.3 months (range, 0.9 to 57.9 months) for all patients and 25.4 months (range, 13.1 to 57.9 months) for those still alive. The median survival for all patients was 25.9 months. The percentage surviving at least 12 months was 75.5% (95% CI, 65.7% to 85.2%). The median overall survival (OS) and progression-free survival (PFS) times for stage III patients (n = 44) were 21.6 months and 10.8 months, respectively. OS and PFS rates at 12 months were 72.7% and 50.0%, respectively. Twelve patients experienced grade >or= 3 lung toxicity (two patients had grade 5 lung toxicity).
The median survival time and OS rate at 12 months for this regimen are encouraging. These results serve as projection expectations for the high-dose radiation arms of the current RTOG 0617 phase III intergroup trial.
To describe the spatial distribution of local-regional recurrence (LRR) among patients treated postoperatively with intensity-modulated radiotherapy (IMRT) for head and neck cancer.
The medical ...records of 90 consecutive patients treated by gross total resection and postoperative IMRT for squamous cell carcinoma of the head and neck from January 2003 to July 2009 were reviewed. Sites of disease were the oral cavity (43 patients), oropharynx (20 patients), larynx (15 patients), and hypopharynx (12 patients). Fifty patients (56%) received concurrent chemotherapy.
Seventeen of 90 patients treated with postoperative IMRT experienced LRR, yielding a 2-year estimate of local regional control of 80%. Among the LRR patients, 11 patients were classified as in-field recurrences, occurring within the physician-designated clinical target volume, and 6 patients were categorized as marginal recurrences. There were no out-of-field geographical misses. Sites of marginal LRRs included the contralateral neck adjacent to the spared parotid gland (3 patients), the dermal/subcutaneous surface (2 patients), and the retropharyngeal/retrostyloid lymph node region (1 patient).
Although the incidence of geographical misses was relatively low, the possibility of this phenomenon should be considered in the design of target volumes among patients treated by postoperative IMRT for head and neck cancer.
Full text
Available for:
GEOZS, IJS, NUK, OILJ, UL, UM, UPUK
PDF
