Publication rates of abstracts presented at the 2007 and 2010 Canadian Association of Radiation Oncology meetings.

BACKGROUND: We set out to determine the rate, time-trend, and defining factors associated with publication of abstracts presented at two annual scientific meetings of the Canadian Association of Radiation Oncology (caro). METHODS: All abstracts accepted for oral presentation in 2007 and 2010 were obtained from the caro program archives and searched using the PubMed database. Variables in the dataset included the year of presentation at caro and of publication in a scientific journal, time to publication (in months), publishing journal, impact factor of publishing journal, abstract research type (clinical, technical, or basic science) and disease site, country of origin, and university of the first author. RESULTS: Overall, 88 of 172 abstracts from the 2007 (n = 102) and 2010 (n = 70) caro meetings were published in peer-reviewed journals (publication rate: 51.2%). Mean time to publication was 18.5 months. Among research types, clinical research (62.5%) and, among disease sites, prostate cancer (40.4%) were most likely to be published. Of all the abstracts, 50.1% were contributed by only 2 universities, a proportion that resembles the overall abstract publication rate of 51.2%. The conversion rate for those 2 universities (51.1%) is very similar to that for all abstracts presented at the two meetings. CONCLUSIONS: Half the abstracts presented at the 2007 and 2010 caro meetings were ultimately published in journals indexed in PubMed by about 1.5 years after presentation. Half the abstracts and publications came from just 2 universities; more must to be done to close the gap.

Sci-Sat AM(2): Brachy-07: Tomosynthesis-based seed reconstruction in LDR prostate brachytherapy: A clinical study.

To develop a tomosynthesis-based dose assessment procedure that can be performed after an I-125 prostate seed implantation, while the patient is still under anaesthesia on the treatment table. Our seed detection procedure involves the reconstruction of a volume of interest based on the backprojection of 7 seed-only binary images acquired over an angle of 60° with an isocentric imaging system. A binary seed-only volume is generated by a simple thresholding of the volume of interest. Seeds positions are extracted from this volume with a 3D connected component analysis and a statistical classifier that determines the number of seeds in each cluster of connected voxels. A graphical user interface (GUI) allows to visualize the result and to introduce corrections, if needed. A phantom and a clinical study (24 patients) were carried out to validate the technique. A phantom study demonstrated a very good localization accuracy of (0.4+/-0.4) mm when compared to CT-based reconstruction. This leads to dosimetric error on D90 and V100 of respectively 0.5% and 0.1%. In a patient study with an average of 56 seeds per implant, the automatic tomosynthesis-based reconstruction yields a detection rate of 96% of the seeds and less than 1.5% of false-positives. With the help of the GUI, the user can achieve a 100% detection rate in an average of 3 minutes. This technique would allow to identify possible underdosage and to correct it by potentially reimplanting additional seeds. A more uniform dose coverage could then be achieved in LDR prostate brachytherapy.

Effects of radiation therapy on vascular responsiveness.

The use of radiation therapy to inhibit vascular proliferative diseases has produced encouraging results in several clinical trials. However, little is known about the possible side effects of radiation on vascular responsiveness. Our goal was to study the in vitro vascular responses of the rabbit aorta to various agonists immediately after several regimens of radiation therapy administered at doses prescribed in clinical protocols and at two different dose rates. High-dose-rate radiation was administered either by brachytherapy, using a gamma source, iridium 192, or an external electron beam producing beta radiation. Low-dose-rate radiation was administered by brachytherapy using a liquid-filled balloon with the beta emitter 32P. Vascular reactivity after the various regimens of irradiation was determined using the organ bath pharmacology assay. Various agonists were applied to the rabbit aorta to produce full cumulative concentration-response curves. Radiation, administered using an external electron beam, did not alter endothelium-dependent relaxation of the aorta induced by acetylcholine. However, the use of a catheter-based system to deliver radiation disrupted the endothelial cell lining of the vessel, causing a lack of relaxation by acetylcholine. Therefore, to compare all modalities of radiation therapy on vascular responsiveness, the agonists used in this study are known to act directly on the smooth muscle. Radiation therapy had no effect on the contractile responses induced by the following agonists: phenylephrine and potassium chloride. Vascular dilatation induced by nitroglycerin, a nitric oxide donor, was unaffected by radiation therapy. The contractile response induced by des-Arg9-bradykinin, a kinin B1 receptor agonist, was significantly increased twofold to threefold by all types of irradiation under study. This enhanced response is attributable to an increase of mRNA levels coding for this receptor. In all cases, radiation therapy did not alter the effective concentration producing 50% of maximal responsiveness (EC50) and did not reduce the vascular responsiveness induced by agonists. Taken together, we conclude that radiation therapy does not hinder endothelium-independent vascular responsiveness and increases the kinin B1 receptor-mediated vasoconstriction.

High dose rate brachytherapy for the local control of endobronchial carcinoma following external irradiation.

BACKGROUND: External irradiation is an established palliative treatment for patients with inoperable lung cancer. However, persistent or recurrent symptoms due to local disase are common following external irradiation. The impact of high dose rate (HDR) brachytherapy in the palliative management of patients with local sequelae of residual or recurrent endobronchial lung carcinoma following external irradiation was investigated. METHODS: A prospective cohort of 29 patients (19 men, mean age 65 years) underwent HDR brachytherapy for inoperable lung cancer. All patients had completed external irradiation at least one month before entry into the study (mean (SD) dose 4400 (1481) cGy, completed 12.9 (21.3) months previously). Patients underwent outpatient bronchoscopic placement of 1-3 HDR brachytherapy catheters for delivery of 750-1000 cGy of intraluminal irradiation every two weeks on 1-3 occasions. Prospective evaluation before and four weeks after completion of HDR brachytherapy included assessment of indices of level of function, symptoms, extent of atelectasis (chest radiography), and bronchoscopic determination of degree of endobronchial obstruction. RESULTS: One hundred and eighteen catheters were placed in 81 treatments. Eleven of the 26 patients who underwent repeat bronchoscopy showed a reduction in the degree of endobronchial obstruction; five of 18 patients had radiographic improvement in the extent of atelectasis. Positive response rates ranged from 25% for signs and symptoms related to pneumonitis to 69% for haemoptysis. Performance status improved in 24% of patients. Two patients died before completion of the study protocol. Short term complications included one episode of non-fatal, massive haemoptysis, five of minor haemoptysis, and one pneumothorax. CONCLUSIONS: HDR brachytherapy may improve the degree of endobronchial obstruction, atelectasis, symptoms, and level of function with minimal short term complications in patients with recurrent or residual symptomatic disease following external irradiation.

The potential uses of high-dose-rate brachytherapy in patients with head and neck cancer.

Brachytherapy has proven to be an extremely valuable method of treatment for head and neck cancer. The data supporting its application, however, is based on continuous low-dose-rate brachytherapy. To benefit from improved radiation protection, outpatient treatments, and increased patient tolerance of treatment set-up over that encountered in conventional low-dose-rate manually afterloaded brachytherapy, we implemented a high-dose-rate remote afterloading approach in selected patients with head and neck cancers. This treatment was utilized in two different roles in managing 29 patients. In its first role, it was used as the sole treatment in 13 patients with T1-2 N0 malignancies. A total of ten treatments of 450-500 cGy each were delivered twice a day with a minimum of 5-6 h between treatments. With a median follow-up of 9 months, only 1 patient failed locally. In a second role, brachytherapy was applied in a post-operative adjuvant setting following wide local excision of tumors in patients who presented with recurrent disease (12 cases) or a second primary in the head and neck (4 cases). All patients had previously received external irradiation to the head and neck. Due to this previous course of irradiation, only eight treatments of 300 cGy each were delivered, for a total of 2400 cGy over a period of 4 days. However, with a follow-up of 2-16 months, only 3 patients remain disease-free.

Metastatic squamous cell carcinoma to cervical lymph nodes from unknown primary mucosal sites.

Between 1978 and 1991, 54 patients with metastatic squamous cell or undifferentiated carcinoma to the cervical lymph nodes, with unknown primary mucosal sites, were treated with curative intent at McGill University teaching hospitals. The median age at diagnosis was 58 years with a male:female ratio of 6:1. All patients presented with a painless neck mass. Five patients (9%) presented with N1 disease, 28 (52%) with N2a disease, four (7%) with N2b disease, three (6%) with N2c disease, and 14 (26%) with N3 disease. Twenty-four patients (44%) underwent neck dissection, and 30 (56%) had only excisional lymph node biopsy. Fifty-three patients (98%) were treated with radiotherapy to a median dose of 60 Gy (range 38 to 66 Gy) in 30 fractions. With a median follow-up time of 49 months, the overall actuarial survival was 63% and 59% at 5 and 10 years, respectively. Three patients were found to have a subsequent primary head and neck tumor. The single most important prognostic factor was the N stage, which influences both neck control and long-term survival. There was no statistically significance difference in survival or local neck control rates between patients who had neck dissection or excisional lymph node biopsy (p > 0.05).

Elevated serum cytokines in patients with malignancy and weight-loss.

Tumour necrosis factor (TNF) has been implicated in the pathogenesis of cachexia in neoplastic and infectious diseases. In our study, the relationship between TNF and other cytokines in patients with malignancy was studied by measuring the serum levels of TNF, Interleukin-I (IL-1), Interleukin-2 (IL-2), and Interleukin-6 (IL-6). Eight patients with cancer had weight loss >10% of their body weight prior to starting anticancer therapy, and their weight loss was not attributable to gastrointestinal disorder, or other medical conditions. Seven patients with malignancy and no weight loss, as well as three normal donors without malignancy were also tested as controls. TNF, IL-1, IL-2 and IL-6 serum levels were determined using a quantitative ELISA test. Elevated levels of TNF, IL-1, IL-2 and IL-6 were detected in 25%, 12.5%, 12.5% and 50% of patients, respectively. In contrast, TNF levels were elevated in 28.5% of seven patients with cancer and no weight loss. In these patients, IL-1, IL-2 and IL-6 levels were undetectable. No TNF, IL-1, IL-2 or IL-6 could be detected in the sera of normal controls. Elevated cytokines serum levels, and especially IL-6, are detected in patients with cancer-cachexia. The determination of such cytokines may have a prognostic value.

Brachytherapy in the treatment of solitary colorectal metastases to the liver.

It is well-established that 30-40% of patients with solitary liver metastases from primary colorectal tumors can be cured by resection. Conventional radiation therapy has had only a palliative role in treating liver metastases because the dose that the liver will tolerate is far below a tumoricidal dose. In contrast, brachytherapy allows one to deliver a tumoricidal dose to the tumor while limiting the dose to surrounding normal tissue to the tolerance dose. As a pilot study, 125I seeds were implanted into unresectable hepatic metastases, or positive margins of resection, at the time of surgery. This report concerns six patients whose liver lesions were the only known site of disease and in whom precipitous drops in carcinembryonic antigen (CEA) levels followed the implants. Recurrence was observed in only one of the 11 implanted site, with a median follow-up of 12 months.

New intraoperative brachytherapy techniques for positive or close surgical margins.

Tumors attached or adjacent to critical structures can often not be completely resected or resected with adequate surgical margins. Sites involving major blood vessels, the paravertebral spaces, or critical abdominal structures often present technical difficulties for standard brachytherapy procedures using I-125 or Ir-192 implants. These techniques allow for a high-dose delivery to the tumor bed with minimal normal tissue toxicity. A relatively simple and accurate method is described using I-125 seeds in Vicryl suture threaded through Gelfoam. These permanent implant procedures with radioactive I-125 seeds effectively treat small residual tumors or suspicious margins where standard brachytherapy techniques may be unsatisfactory and technically difficult to perform.