The potential advantages of (18)FDG PET/CT-based target volume delineation in radiotherapy planning of head and neck cancer.

PURPOSE: This study investigated two fixed threshold methods to delineate the target volume using (18)FDG PET/CT before and during a course of radical radiotherapy in locally advanced squamous cell carcinoma of the head and neck. MATERIALS AND METHODS: Patients were enrolled into the study between March 2006 and May 2008. (18)FDG PET/CT scans were carried out 72h prior to the start of radiotherapy and then at 10, 44 and 66Gy. Functional volumes were delineated according to the SUV Cut Off (SUVCO) (2.5, 3.0, 3.5, and 4.0bwg/ml) and percentage of the SUVmax (30%, 35%, 40%, 45%, and 50%) thresholds. The background (18)FDG uptake and the SUVmax within the volumes were also assessed. RESULTS: Primary and lymph node volumes for the eight patients significantly reduced with each increase in the delineation threshold (for example 2.5-3.0bwg/ml SUVCO) compared to the baseline threshold at each imaging point. There was a significant reduction in the volume (p⩽0.0001-0.01) after 36Gy compared to the 0Gy by the SUVCO method. There was a negative correlation between the SUVmax within the primary and lymph node volumes and delivered radiation dose (p⩽0.0001-0.011) but no difference in the SUV within the background reference region. The volumes delineated by the PTSUVmax method increased with the increase in the delivered radiation dose after 36Gy because the SUVmax within the region of interest used to define the edge of the volume was equal or less than the background (18)FDG uptake and the software was unable to effectively differentiate between tumour and background uptake. CONCLUSIONS: The changes in the target volumes delineated by the SUVCO method were less susceptible to background (18)FDG uptake compared to those delineated by the PTSUVmax and may be more helpful in radiotherapy planning. The best method and threshold have still to be determined within institutions, both nationally and internationally.

Non-surgical treatment of localised prostate cancer.

The non-surgical treatment of localised prostate cancer depends on a number of factors including: PSA, stage, Gleason score, age, fitness for treatment and life expectancy, and is individualised depending on risk. Patients who present with early localised (stage T1 or T2) tumours with low risk features (PSA <10 ng/ml, Gleason score 3+4 or below) and who have a life expectancy of more than 10 years may consider radiotherapy or active surveillance. Permanent brachytherapy seed implantation is suitable for low risk patients who have minimal lower urinary tract symptoms, with equivalent results to external beam radiotherapy Conformal high-dose external beam radiotherapy is effective for patients with high risk disease, and consideration should be given to the use of neoadjuvant and adjuvant anti-androgens. Prophylactic pelvic nodal irradiation is indicated for patients with high risk of lymph node disease, followed by a boost to the prostate using either a smaller external beam volume, or brachytherapy. The definitive treatment depends on both clinical parameters such as the clinical staging, prognostic risk, and the likelihood of acute and late toxicity and the patient's personal choice based on their life style.