Michael MacManus

Fluorine-18 fluorodeoxyglucose Positron emission tomography, Gallium-67 scintigraphy, and conventional staging for Hodgkin's disease and non-Hodgkin's lymphoma

PURPOSE To compare fluorine-18 fluorodeoxyglucose positron emission tomography (PET) and gallium scanning with each other and with conventional staging, for patients with Hodgkins disease or non-Hodgkins lymphoma. SUBJECTS AND METHODS Fifty patients had PET, gallium scanning, and conventional staging of newly diagnosed or progressive Hodgkins disease or non-Hodgkins lymphoma. Disease sites, stage, and treatment plans were assessed retrospectively. RESULTS Positron emission tomography and gallium scanning each upstaged 14% of patients (n = 7). Management was altered by PET in 9 cases (18%) and by gallium scanning in 7 (14%, P = 0.6). Disease was evident in 117 sites in 42 patients. The case positivity rate for conventional assessment was 90%; for PET, 95%; for gallium scanning, 88%; for conventional assessment plus PET, 100%; and for conventional assessment plus gallium scanning, 98%. Site positivity rates for conventional assessment were 68%; for PET, 82%; for gallium scanning, 69% (conventional vs. PET, P = 0.01; conventional vs. gallium scanning, P = 0.9; PET vs. gallium scanning, P = 0.01); for conventional assessment plus PET, 96%; and for conventional assessment plus gallium scanning, 94%. Positron emission tomography and gallium scanning were entirely concordant in 31 patients; in the other 19 patients, PET identified 25 sites missed by gallium scanning, whereas gallium scanning identified 10 sites missed by PET. CONCLUSION In this retrospective study, PET demonstrated a higher site positivity rate than did gallium scanning, with similar case positivity rates. These data support the use of PET in place of gallium scanning for the staging of patients with Hodgkins disease or non-Hodgkins lymphoma.

Stereotactic radiotherapy for pulmonary oligometastases: a systematic review.

Introduction: Hypofractionated stereotactic body radiotherapy (SBRT) is an emerging noninvasive technique for the treatment of oligometastatic cancer. The use of small numbers of large doses, should in theory, achieve high rates of local control. The aim of this literature review is to critically assess the use of SBRT for the treatment of pulmonary metastases as judged by its effect on local control, survival, and toxicity. Methods: A systematic literature search was performed. Both single fraction stereotactic radiosurgery (SRS) and hypofractionated radiotherapy (SBRT) were considered individually. Thirteen institutions reported results regarding SBRT and seven institutions regarding SRS (a total of 29 publications). Outcomes, techniques, radiobiology, and the scientific rigor of the reported studies were analyzed. Results: A wide range of techniques, doses, and dose fractionation schedules were found. Three hundred thirty-four patients with 564 targets were reported in the SBRT series. The 2-year weighted local control was 77.9%. The corresponding 2-year weighted overall survival was 53.7%, with a 4% rate of grade 3 or higher radiation toxicities. One hundred fifty-four patients with 174 targets were treated in the SRS series. The 2-year weighted local control was 78.6%. The corresponding weighted 2-year overall survival was 50.3%, with 2.6% rate of grade 3 or higher toxicities. Conclusion: There was insufficient evidence to recommend a consensus view for optimal tumor parameters, dose fractionation, and technical delivery of treatment. This indicates the need for further prospective studies. However, high local control rates that could potentially lead to a survival benefit justifies the consideration of stereotactic radiotherapy for patients with limited pulmonary oligometastases.

Clinical Impact of 18F Fluorodeoxyglucose Positron Emission Tomography in Patients With Non–Small-Cell Lung Cancer: A Prospective Study

PURPOSE To prospectively study the impact of (18)F fluorodeoxyglucose (FDG) positron emission tomography (PET) on clinical management of patients with non-small-cell lung cancer (NSCLC). PATIENTS AND METHODS One hundred five consecutive patients with NSCLC undergoing (18)F FDG PET were analyzed. Before PET, referring physicians recorded scan indication, conventional clinical stage, and proposed treatment plan. PET scan results were reported in conjunction with available clinical and imaging data, including results of computed tomography (CT). Subsequent management and appropriateness of PET-induced changes were assessed by follow-up for at least 6 months or until the patients death. RESULTS Indications for PET were primary staging (n = 59), restaging (n = 34), and suspected malignancy subsequently proven to be NSCLC (n = 12). In 27 (26%) of 105 of cases, PET results led to a change from curative to palliative therapy by upstaging disease extent. Validity of the PET result was established in all but one case. PET appropriately downstaged 10 of 16 patients initially planned for palliative therapy, allowing either potentially curative treatment (four patients) or no treatment (six patients). PET influenced the radiation delivery in 22 (65%) of 34 patients who subsequently received radical radiotherapy. Twelve patients considered probably inoperable on conventional imaging studies were downstaged by PET and underwent potentially curative surgery. PET missed only one primary tumor (5-mm scar carcinoma). CT and PET understaged three of 20 surgical patients (two with N1 lesions < 5 mm and one with unrecognized atrial involvement), and PET missed one small intrapulmonary metastasis apparent on CT. No pathological N2 disease was missed on PET. CONCLUSION FDG PET scanning changed or influenced management decisions in 70 patients (67%) with NSCLC. Patients were frequently spared unnecessary treatment, and management was more appropriately targeted.

Overview of early response assessment in lymphoma with FDG-PET

Early assessment of response to chemotherapy with fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) is becoming a routine part of management in patients with Hodgkin lymphoma (HL) and histologically aggressive non-Hodgkin lymphoma (NHL). Changes in FDG uptake can occur soon after the initiation of therapy and they precede changes in tumour volume. Recent studies in uniform populations of aggressive lymphomas (predominantly diffuse large B cell lymphomas) and HL have clarified the value of early response assessment with PET. These trials show that PET imaging after 2–3 chemotherapy cycles is far superior to CT-based imaging in predicting progression-free survival and can be at least as reliable as definitive response assessment at the end of therapy. This information is of great potential value to patients, but oncologists should be cautious in the use of early PET response in determining choice of therapy until some critical questions are answered. These include: When is the best time to use PET for response assessment? What is the best methodology, visual or quantitative? (For HL at least, visual reading appears superior to an SUV-based assessment). Can early responders be cured with less intensive therapy? Will survival be better for patients treated more intensively because they have a poor interim metabolic response? In the future, early PET will be crucial in developing response-adapted therapy but without further carefully designed clinical trials, oncologists will remain uncertain how best to use this new information.

PET scans in radiotherapy planning of lung cancer

Accurate delineation of the primary tumor and of involved lymph nodes is a key requisite for successful curative radiotherapy in non-small cell lung cancer (NSCLC). In recent years, it has become clear that the incorporation of FDG PET-CT scan information into the related processes of patient selection and radiotherapy planning has lead to significant improvements for patients with NSCLC. The use of FDG PET-CT information in radiotherapy planning allows better target volume definition, reduces inter-observer variability and encourages selective irradiation of involved mediastinal lymph nodes. PET-CT also opens the door for innovative radiotherapy delivery and the development of new concepts. However, care must be taken to avoid a variety of technical pitfalls and specific education is necessary, for clinicians and physicists alike.

Ocular Risks From Orbital and Periorbital Radiation Therapy: A Critical Review

Radiation therapy (RT) plays an essential role in the treatment of a wide range of tumors that arise in the orbit, invade the orbit, or are located in close proximity to it. Partial or total orbital irradiationmay cause awide spectrum of early and late toxicities, ranging from transient irritation to permanent blindness. Fastidious treatment planning and treatment delivery, informed by detailed knowledge of the effects of RTon ocular structures, can help minimize the risk of toxicity. The purpose of this article is to provide an overview of the potential complications of orbital radiotherapy and discuss their prevention and management. We discuss each major region of the orbit and globe in turn and where possible have made recommendations for the management of RTrelated toxicities. However, few prospective studies exist in this area of medicine, and therefore the evidence base is often weak. The authoritative QANTEC (1) reviews of normal tissue effects in the clinic, published recently in this journal (2) considered the effects of RT on the optic nerve but due to lack of high quality quantitative data did not consider other orbital subsites. We have confined our discussion largely to external beam RTwith photon or electron beams.

PET/CT imaging for target volume delineation in curative intent radiotherapy of non-small cell lung cancer: IAEA consensus report 2014

This document describes best practice and evidence based recommendations for the use of FDG-PET/CT for the purposes of radiotherapy target volume delineation (TVD) for curative intent treatment of non-small cell lung cancer (NSCLC). These recommendations have been written by an expert advisory group, convened by the International Atomic Energy Agency (IAEA) to facilitate a Coordinated Research Project (CRP) aiming to improve the applications of PET based radiation treatment planning (RTP) in low and middle income countries. These guidelines can be applied in routine clinical practice of radiotherapy TVD, for NSCLC patients treated with concurrent chemoradiation or radiotherapy alone, where FDG is used, and where a calibrated PET camera system equipped for RTP patient positioning is available. Recommendations are provided for PET and CT image visualization and interpretation, and for tumor delineation using planning CT with and without breathing motion compensation.

18F-FDG PET Provides High-Impact and Powerful Prognostic Stratification in the Staging of Merkel Cell Carcinoma: A 15-Year Institutional Experience

Merkel cell carcinoma (MCC) is a rare but aggressive skin cancer with limited evidence on the role of PET scanning. The primary aim of this study was to assess the impact of 18F-FDG PET in the staging and management of MCC. Methods: A single-institution review using clinical outcome data collected until February 2012 was performed of patients with MCC who underwent staging PET scanning between January 1997 and October 2010. Management plans were recorded prospectively at the time of the PET request, and follow-up outcomes were recorded retrospectively. The clinical impact of PET was scored using our previously published criteria: “high” if the PET scan changed the primary treatment modality or intent; “medium” if the treatment modality was unchanged but the radiation therapy technique or dose was altered. The primary objective was to test the hypothesis that the true proportion of patients who have a high- or medium-impact scan would be greater than 25%. Results: The median follow-up of 102 consecutive patients was 4.8 y. The results of staging PET had an impact on patient management in 37% of patients (P < 0.003). High- and medium-impact scans were recorded for 22% and 15% of patients, respectively. PET staging results differed from conventional staging results in 22% of patients, with PET upstaging 17% and downstaging 5%. The 3- and 5-y overall survival was 60% (95% confidence interval, 50%–71%) and 51% (95% confidence interval, 41%–64%), respectively. In stratification by PET-defined stage, the 5-y overall survival was 67% for patients with stage I/II disease but only 31% for patients with stage III disease (log-rank P < 0.001). The 5-y cumulative incidence of locoregional failure, distant failure, and death was 16.6%, 22.3% and 14.3%, respectively. On multivariate analysis, only PET stage (P < 0.001) and primary treatment modality (P = 0.050) were significantly associated with overall survival. The primary treatment modality was not associated with progression-free survival when stratification was by tumor stage. Conclusion: The use of 18F-FDG PET scans had a great impact on patients and may play an important role in the prognostic stratification and treatment of this disease.

High rates of tumor growth and disease progression detected on serial pretreatment fluorodeoxyglucose-positron emission tomography/computed tomography scans in radical radiotherapy candidates with nonsmall cell lung cancer.

The authors studied growth and progression of untreated nonsmall cell lung cancer (NSCLC) by comparing diagnostic and radiotherapy (RT) planning fluorodeoxyglucose (FDG)‐positron emission tomography (PET)/computed tomography (CT) scans before proposed radical chemo‐RT.

Imaging of hypoxia with 18F-FAZA PET in patients with locally advanced non-small cell lung cancer treated with definitive chemoradiotherapy

For many cancers, tumour hypoxia is an adverse prognostic factor, and increases chemoradiation resistance; its importance in non‐small cell lung cancer (NSCLC) is unproven. This study evaluated tumoural hypoxia using fluoroazomycin arabinoside (18F‐FAZA) positron emission tomography (PET) scans among patients with locoregionally advanced NSCLC treated with definitive chemoradiation.