A practical method to detect target failure of a helical tomotherapy unit

PURPOSE

Helical tomotherapy has been in clinical use for several years. One of the issues with a helical tomotherapy unit is the failure of detection of the x-ray target. In this study, we are proposing a method to detect potential failure of the x-ray target.

METHODS

Currently, on-board detector data from a helical tomotherapy unit are collected and sent to TomoTherapy Inc. for comparison with the so-called gold standard for the unit. However, this is sometimes time-consuming. Furthermore, the clinical medical physicists have no access to this comparison procedure. In this study, we developed a practical method to detect target failure based on one of the monthly quality assurance (QA) procedures. The commissioning cross-plane profiles were used as the comparison baseline. Larger EDR2 film (35×43 cm) were set at source-axis distance (SAD) (85 cm) and shot with 1.5 cm solid water as build-up material and 10 cm solid water as backscattering material. Cross-plane profiles obtained from the EDR2 film were compared with the commissioning profiles.

RESULTS

When the cross-plane profiles from monthly QA have 1° degree difference from the commissioning profiles, it is time that the target be changed.

CONCLUSION

This method enables the clinical medical physicists to easily evaluate the target status and to help improving the quality assurance of a helical tomotherapy unit.

Impact of pulse forming network and injection current parameters on output and energy variations of helical tomotherapy

PURPOSE

In this study, an experiment was devised to establish the dependency of the impact of pulse forming network (PFN) and injection current (IC) parameters on output and energy variations of helical tomotherapy (HT) on the radiation beam output and energy.

METHODS

HT has unique radiation beam characteristics due to the absence of a flattening filter. As with conventional linear accelerators, the machine output and energy should be within a + or - 2% tolerance according to published studies. However, because a dose servo is not utilized in a HT unit, these parameters may drift out of the + or - 2% tolerance due to various reasons such as high machine temperatures. With this in mind, physicists and engineers must adjust certain machine parameters to reset the output and energy to within the tolerance of the commissioned baseline. Two parameters commonly adjusted are: PFN voltage (V(PFN)) and IC voltage (V(IC)).

RESULTS

Results showed that the HT unit possesses different working zones defined by the V(PFN) and V(IC) parameter settings. The working zones were classified into 5 zones: 1) low dose rate zone - radiation dose rate much lower than nominal dose rate and machine cannot run due to low dose rate fault; 2) normal dose rate zone - dose rate is within tolerance of nominal dose rate and machine can run without dose rate fault; 3) dose rate failure during treatment zone - dose rate within the tolerance of the nominal dose rate however machine interrupts during treatment due to dose rate fault; 4) high dose rate zone - dose rate is higher than nominal dose rate and machine cannot run due to high dose rate fault; and 5) inoperable dose rate zone - dose rate is much higher than the nominal dose rate and machine cannot run.

CONCLUSION

The results of this study may provide a quick guide for physicists to adjust their HT unit V(PFN) and V(IC) values in order to reset the radiation beam output and energy back to within the tolerance of the commissioned baseline.

Prognostic time dependence of deletions affecting codons 557 and/or 558 of KIT gene for relapse-free survival (RFS) in localized GIST: a Spanish Group for Sarcoma Research (GEIS) Study

BACKGROUND

To assess whether deletions involving codons 557 and/or 558 (critical deletions) of exon 11 of KIT are relevant in the prognosis of relapse-free survival (RFS) in gastrointestinal stromal tumor (GIST) patients with a long follow-up.

PATIENTS AND METHODS

A univariate and multivariate analysis for RFS were carried out on 162 localized GIST patients over the entire follow-up period and over the intervals 0-4 years and >4 years. Factors assessed among others were Fletcher/National Institutes of Health and Miettinen-Lasota/Armed Forces Institute of Pathology (M-L/AFIP) risk categories, critical deletions and non-deletion-type mutation (NDTM) within exon 11 of KIT.

RESULTS

Multivariate analyses revealed that M-L/AFIP [relative risk (RR) 11.45, confidence interval (CI) 4.40-29.76, for the high-risk subgroup and RR 5.97, CI 2.09-17.06, for the intermediate subgroup] and critical deletions (RR 3.05, CI 1.59-5.85) were independent prognostic factors for RFS for the first 4 years and for the entire follow-up period. Beyond 4 years, the high-risk M-L/AFIP subgroup (RR 8.12, CI 1.48-44.4) and NDTM (RR 6.42, CI 1.17-35.12) were independent prognostic factors for RFS. The median follow-up was 84 months.

CONCLUSION

Critical deletions represent a time-dependent prognostic factor limited to the first 4 years after surgery, which could help identify a subset with higher and earlier risk for relapse in GIST patients.

Management of symptoms in amyotrophic lateral sclerosis

The mainstay of treatment of amyotrophic lateral sclerosis (ALS) is management of symptoms. Health care providers involved in the care of ALS patients should be armed with the most current knowledge about symptomatic management of these patients so that an aggressive approach to controlling symptoms can be undertaken at the most appropriate time. Among the important modalities is noninvasive positive pressure ventilation, which has been shown to improve not only quality of life but also survival. Similarly, clinicians should consider earlier intervention with enteral feeding. Palliative care should begin soon after ALS is diagnosed.

Gemcitabine and Oxaliplatinum: An Effective Regimen in a Patient with Progressive Refractory Mantle Cell Lymphoma

We report here a 68-year-old man with progressive refractory Mantle cell Lymphoma stage IV-A, treated with different chemotherapeutic drugs. With no therapeutic options we decided to treat him with oxaliplatinum-gemcitabine regimen, based on the proven efficacy and synergy of these drugs in other tumors and lymphomas. Treatment was well tolerated and patient achieved a maintained complete remission with 6 months of follow up. We consider that this may be a salvage therapeutic option for patients with mantle cell lymphoma.

PX-171–006: Phase Ib multicenter dose escalation study of carfilzomib (CFZ) plus lenalidomide (LEN) and low-dose dexamethasone (loDex) in relapsed and refractory multiple myeloma (MM): Preliminary results

8541

Background: CFZ is a highly specific proteasome inhibitor with single agent activity in relapsed/refractory MM (ASH 2008). The purpose of this study is to evaluate the safety and activity of CFZ in combination with LEN and loDex. Methods: This phase Ib trial evaluates 4 dose levels (≥ 3 pts each) to define the maximum tolerated dose (MTD) of CFZ/LEN/loDex in relapsed/refractory MM pts who failed 1–3 prior therapies, including prior LEN or bortezomib (BTZ). CFZ IV 15- 20 mg/m2 (d1,2,8,9,15,16), LEN 10–20 mg po (d1–21) and loDex 40 mg po (d1, 8, 15, 22) in 28-day cycles (C). An additional 10–15 pts will be evaluated at the highest dose level reached. Dose limiting toxicity (DLT) has been defined as grade (G) ≥ 3 non- hematologic; G4 neutropenia for > 7d and/or neutropenic fever; G4 thrombocytopenia > 7d or G3-G4 thrombocytopenia in association with bleeding. Overall response (CR/sCR, VGPR/PR) is assessed by IWG criteria, with secondary assessment by modified EBMT criteria which includes MR. Results: 11 pts have been enrolled. 8/11 are evaluable for response and toxicity. Median prior lines of therapy was 2 (range 2–3). Prior therapies included DEX (8/8), BTZ (6/8), LEN (7/8), alkylators (6/8), anthracyclines (5/8), stem cell transplant (5/8), and thalidomide (1/8); 6/8 pts had received both LEN and BTZ. MTD has not yet been reached after the first 2 dose cohorts. No drug related SAEs or G3/4 treatment emergent AEs were reported. Responses to date with a median of 2 C (range 1–4) are shown below. Responses were rapid and occurred within the first 28-day cycle. Conclusions: CFZ/LEN/loDex in combination was well tolerated in the first 2 cohorts. There have been no myleosuppressive or renal DLTs. The combination has achieved early encouraging responses in pts who had failed both LEN and BTZ at doses well below the single agent MTD of either LEN or CFZ. Dose escalation is ongoing. Updated data will be presented at the meeting.

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Dose-dense epirubicin with paclitaxel as preoperative treatment in locally advanced breast cancer: Phase II trial

e11633

Background: Treatment of locally advanced breast cancer (LABC) with anthracycline-based regimens have pathological complete response (pCR) of 10–15%, and with anthracyclin-taxane therapy have pCR 18–30%. Combined or sequential are both acceptable with the most important agents. Methods: We use a dose- dense regimen epirubicin and paclitaxel for 12 weeks to determine the effectiveness in the neoadjuvant setting could increase pCR and safety of the regimen. This phase II study investigated women with untreated locally advanced breast cancer assigned to receive epirrubicina 25 mg/m2 and paclitaxel 70 mg/m2 for twelve weeks. Results: 21 patients were enrolled at median follow up of eight months. The median age was 55 years old (28–67). The distribution by TNM was IIB (15%), IIIA (52%), IIIB (24%) y IIIC (9%) and tumor type was lobular (24%) and ductal (76%). The mean tumor size was 8 cm (5 -14 cm). Ninety percent completed twelve cycles of chemotherapy with a two hundred forty five cycles administered. In six patients had dose reduction by 10–20% in subsequent doses and one patient withdrawn from de study because of chemotherapy related toxicity. In 9 percent of patients we use G-SCF. Surgery was performed in 18 patients. Eleven patients (52%) achieved a clinical response (PR o CR) after twelve cycles. Complete pathological response and partial was 11% y 14%. Subset analysis of the effect of Independent predictors included receptor status, Her2 neu, tumor size, and histology was no statistically significant (p.68). Treatment was generally well tolerated. Grade 3/4 non-hematologic adverse events (neurotoxicity, nauseas and palmar plantar dysesthesia) events occurred in 5% of patients. No cardiac toxicity was found. Conclusions: Despite the small sample size, it was representative of our population of LABC. These data indicate that the combined regimen in dose-dense epirubicin and paclitaxel is a regimen with acceptable toxicity. However we have low percent of cPR, maybe we have a high percent of patients with stage IIIA and IIIB with large diameter of tumor size.

No significant financial relationships to disclose.

A short-term biomarker modulation prevention study of anastrazole in women at increased risk for breast cancer

1514

Background: Selective estrogen receptor modulators (SERMs) reduce the risk of breast cancer. Acceptance of SERMs is low due to toxicities. Agents with a better toxicity profile and surrogate endpoint biomarkers to evaluate the effect of preventive agents are needed. In addition to reducing the risk of recurrence of breast cancer, the aromatase inhibitors (AI) have been shown to reduce the risk of contralateral breast cancer in large phase III adjuvant studies. Our objective in this prospective short-term prevention study was to evaluate the effect of anastrozole on surrogate endpoint biomarkers in breast tissue and serum of women with breast cancer who are at increased risk for developing a contralateral second primary breast cancer. Methods: Women with a history of stage I, II breast cancer who were scheduled to start anastrozole for standard adjuvant treatment were eligible. After signing informed consent, patients underwent baseline fine needle aspiration (FNA) of the unaffected breast and serum collection for biomarker analysis before starting anastrozole at 1 mg per oral /day. A repeat FNA and serum collection were performed after 6 months of therapy. Biomarker endpoints included changes in ER and KI-67 expression in breast tissue analyzed by immunohistochemistry and insulin-like growth factor binding protein (IGFBP-1) in serum analyzed by ELISA. The difference in biomarkers before and after treatment was assessed using a Wilcoxon signed-rank test. Results: Forty two patients were enrolled and accrual has been completed. Median age was 58.8 (range 48–75). There was no change in ER or Ki-67 expression in pre- and posttreatment FNA samples. However, there was a statistically significant difference in pre- and posttreatment serum IGFBP-1 levels (p = 0.014); with pre-and post- mean treatment levels being 9.2 ng/mL and 13.5 ng/mL, respectively. Conclusions: We found a significant modulation of IGFBP-1 levels with 6 months of anastrozole treatment in women at increased risk of developing contralateral breast cancer. Anastrozole is currently being studied as a prevention agent in a large phase III trial, and our results provide support for continued evaluation of IGFBP-1 as a surrogate endpoint biomarker in prospective breast chemoprevention studies.

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Neuralgic amyotrophy

Neuralgic amyotrophy has a broad variety of clinical manifestations. Although it was initially thought to be a plexopathy, its diverse presentation can include isolated sensory nerves or even cranial nerves. Although neuralgic amyotrophy is usually a benign condition with a good recovery, pain can be a disabling feature. NSAIDs and short-term narcotics are appropriate treatments. There is lack of evidence whether the use of corticosteroids has an impact on the duration of the disease or the neuropathic pain. However, given the few adverse effects in a selective population and low cost, short-term steroids can be an option for the treatment of these patients.