Assessing the impact of FDG-PET in the management of anal cancer.

PURPOSE: To assess the utility of FDG-PET in anal cancer for staging and impact on radiotherapy planning (RTP), response and detection of recurrent disease. METHODS AND MATERIALS: Fifty histopathological anal cancer patients were reviewed between 1996 and 2006. The median age was 58 years (range 36-85) with 19 males:31females. Clinical assessment with CT was compared to PET. Impact on management, disease response, recurrence and metastases was evaluated. RESULTS: The non-PET staging was Stage I(8), Stage II(18), Stage III(22), and Stage IV(2)s. The primary was strongly FDG avid in 98% with non-excised tumors compared to CT (58%). PET upstaged 17% with unsuspected pelvic/inguinal nodal disease. Pre-treatment PET identified 11 additional by involved nodal groups in 48 patients causing RTP amendments in 19%. Post-treatment PETs at median 17 weeks (range 9-28) showed complete responses in 20 (80%) and 5 (20%) partial responses (PR). PRs were biopsy positive in 2 and negative in 3. Fifteen had follow-up scans of which all nine PETs detected recurrences were pathologically confirmed. CONCLUSIONS: Anal cancer is FDG-PET avid. PET upstages 17% and changes the RTP in 19%. PET can aid in anal cancer staging and identification of residual disease, recurrent/metastatic disease but warrants further prospective studies.

Imaging in pleural mesothelioma: a review of the 11th International Conference of the International Mesothelioma Interest Group.

Imaging of malignant pleural mesothelioma (MPM) is essential to the diagnosis, assessment, and monitoring of this disease. The complex morphology and growth pattern of MPM, however, create unique challenges for image acquisition and interpretation. These challenges have captured the attention of investigators around the world, some of whom presented their work at the 2012 International Conference of the International Mesothelioma Interest Group (iMig 2012) in Boston, Massachusetts, USA, September 2012. The measurement of tumor thickness on computed tomography (CT) scans is the current standard of care in the assessment of MPM tumor response to therapy; in this context, variability among observers in the measurement task and in the tumor response classification categories derived from such measurements was reported. Alternate CT-based tumor response criteria, specifically direct measurement of tumor volume change and change in lung volume as a surrogate for tumor response, were presented. Dynamic contrast-enhanced CT has a role in other settings, but investigation into its potential use for imaging mesothelioma tumor perfusion only recently has been initiated. Magnetic resonance imaging (MRI) and positron-emission tomography (PET) are important imaging modalities in MPM and complement the information provided by CT. The pointillism sign in diffusion-weighted MRI was reported as a potential parameter for the classification of pleural lesions as benign or malignant, and PET parameters that measure tumor activity and functional tumor volume were presented as indicators of patient prognosis. Also reported was the use of PET/CT in the management of patients who undergo high-dose radiation therapy. Imaging for MPM impacts everything from initial patient diagnosis to the outcomes of clinical trials; iMig 2012 captured this broad range of imaging applications as investigators exploit technology and implement multidisciplinary approaches toward the benefit of MPM patients.

Comparison of toxicity and outcomes of concurrent radiotherapy with carboplatin/paclitaxel or cisplatin/etoposide in stage III non-small cell lung cancer.

Concurrent chemoradiotherapy (CCRT) has become the standard of care for patients with unresectable stage III non-small cell lung cancer (NSCLC). The comparative merits of two widely used regimens: carboplatin/paclitaxel (PC) and cisplatin/etoposide (PE), each with concurrent radiotherapy, remain largely undefined. Records for consecutive patients with stage III NSCLC treated with PC or PE and ≥60 Gy chest radiotherapy between 2000 and 2011 were reviewed for outcomes and toxicity. Survival was estimated using the Kaplan-Meier method and Cox modeling with the Wald test. Comparison across groups was done using the student's t and chi-squared tests. Seventy-five (PC: 44, PE: 31) patients were analyzed. PC patients were older (median 71 vs. 63 years; P = 0.0006). Other characteristics were comparable between groups. With PE, there was significantly increased grade ≥3 neutropenia (39% vs. 14%, P = 0.024) and thrombocytopenia (10% vs. 0%, P = 0.039). Radiation pneumonitis was more common with PC (66% vs. 38%, P = 0.033). Five treatment-related deaths occurred (PC: 3 vs. PE: 2, P = 1.000). With a median follow-up of 51.6 months, there were no significant differences in relapse-free survival (median PC 12.0 vs. PE 11.5 months, P = 0.700) or overall survival (median PC 20.7 vs. PE 13.7 months; P = 0.989). In multivariate analyses, no factors predicted for improved survival for either regimen. PC was more likely to be used in elderly patients. Despite this, PC resulted in significantly less hematological toxicity but achieved similar survival outcomes as PE. PC is an acceptable CCRT regimen, especially in older patients with multiple comorbidities.

Establishing locoregional control of malignant pleural mesothelioma using high-dose radiotherapy and (18) F-FDG PET/CT scan correlation.

INTRODUCTION: The management of malignant pleural mesothelioma represents one of the most challenging issues in oncology, as there is no proven long-term benefit from surgery, radiotherapy or chemotherapy alone or in combination. Locoregional progression remains the major cause of death, but radical surgical resection may produce major postoperative morbidity. While radical or postoperative radiotherapy using conventional techniques has resulted in severe toxicity with no impact on survival, recent advances in radiotherapy delivery may be more effective. METHODS: We treated patients with locally advanced mesothelioma whose tumours had been sub optimally resected with high-dose three-dimensional conformal radiotherapy (3DCRT) or intensity-modulated radiotherapy (IMRT) to large volumes of one hemithorax, using CT and positron emission tomography (PET) scan-based treatment planning. Clinical outcomes were assessed by determining patterns of failure and metabolic changes in total glycolytic volume (TGV) between pre- and post-irradiation( 18) F-FDG PET/CT scans and by recording acute and late toxicity grades. RESULTS: Fourteen patients were analysed with 40 PET scans performed before and up to 4.5years after radiotherapy. Eleven patients had pleurectomy/decortications, one had an extrapleural pneumonectomy and two had no surgery. Four patients who received chemotherapy had all progressed prior to radiotherapy. After radiotherapy, the in-field local control rate was 71%. No progression occurred in two patients, one was salvaged with further radiotherapy to a new site, four recurred inside the irradiated volume all with concurrent distant metastases and the other seven had distant metastases only. The TGVs were reduced by an average of 67% (range 12-100%) after doses of 45 to 60Gy to part or all of one hemithorax. There were no serious treatment-related toxicities. Median survival was 25months from diagnosis and 17months after starting radiotherapy. CONCLUSIONS: We have established that mesothelioma can be locally controlled with high radiation doses using 3DCRT or IMRT, and that strict normal tissue dose constraints have limited radiation toxicities. Radiotherapy should be considered to prevent or delay the local manifestations of progressive disease in suitable patients after surgery including extrapleural pneumonectomy and pleurectomy/decortication. Higher radiation doses may allow more effective palliation.

The use of PET in assessing tumor response after neoadjuvant chemoradiation for rectal cancer.

PURPOSE: To assess the correlation of 18F-FDG-PET (PET) response to pathological response after neoadjuvant chemoradiation (CRT) for locally advanced rectal cancer. METHODS AND MATERIALS: Twenty patients with locally advanced rectal cancer were identified between 2001 and 2005. The median age was 57 years (range 37-72) with 14 males and 6 females. All patients were staged with endorectal ultrasound and/or MRI, CT, and PET. The clinical staging was T3N0M0 (16), T3N1M0 (2), and T3N0M1 (2). Restaging PET was performed after CRT, and prior to definitive surgery. The response on PET and pathology was assessed and correlated. Patient outcome according to PET response was also assessed. RESULTS: Following CRT, a complete PET response occurred in 7 patients, incomplete response in 10, and no response in 3 patients. At surgery, complete pathological response was recorded in 7 patients, incomplete response in 10 and no response in 3. There was a good correlation of PET and pathological responses in complete responders (5/7 cases) and non-responders (3/3 cases). After a median follow-up of 62 months (range 7-73), twelve patients were alive with no evidence of disease. All patients achieving complete metabolic response were alive with no evidence of disease, while as those who had no metabolic response, all died as a result of metastatic disease. CONCLUSIONS: PET is a promising complementary assessment tool for assessing tumor response after CRT if there is a complete or no response. PET response may also predict for outcome.

Impact of oedema on implant geometry and dosimetry for temporary high dose rate brachytherapy of the prostate.

The optimal timing of dosimetry for permanent seed prostatic implants remains contentious given the half life of post-implant oedema resolution. The aim of this study was to establish whether prostatic oedematous change over the duration of a temporary high dose rate (HDR) interstitial brachytherapy (BR) boost would result in significant needle displacement, and whether this change in geometry would influence dosimetry. Two CT scans, one for dosimetric purposes on the day of the implant and the second just prior to implant removal, were obtained for four patients receiving transperineal interstitial prostate brachytherapy. The relative changes in cross-sectional dimensions of the implants were calculated by establishing the change in mean radial distance (MRD) of the needle positions from the geometric centre of the implant for each patient's pair of CT studies. The treatment plan, as calculated from the first CT scan, was used in the second set of CT images to allow a comparison of dose distribution. The percentage change in MRD over the duration of the temporary implants ranged from -1.91% to 1.95%. The maximum change in estimated volume was 3.94%. Dosimetric changes were negligible. In the four cases studied, the degree of oedematous change and consequent displacement of flexiguide needle positions was negligible and did not impact on the dosimetry. The rate and direction of oedematous change can be extremely variable but on the basis of the four cases studied and the results of a larger recent study, it might not be necessary to re-image patients for dosimetric purposes over the duration of a fractionated HDR BT boost to the prostate where flexiguide needles are utilized. Nevertheless, further investigation with larger patient numbers is required.