Purpose
Variation in target volume delineation represents a significant hurdle in clinical trials involving conformal radiotherapy. We sought to determine the impact of a consensus guideline-based visual atlas on contouring of target volumes.
Methods
A representative case and target volume delineation instructions derived from a proposed rectal cancer clinical trial involving conformal radiotherapy were contoured (Scan1) by 14 physician observers and a reference expert. Gross tumor volume (GTV), and 2 clinical target volumes (CTVA, comprising internal iliac, pre-sacral, and peri-rectal nodes, and CTVB, external iliac nodes) were contoured. Observers were randomly assigned to receipt (Group_A) /non-receipt (Group_B) of a consensus guideline and atlas for anorectal cancers, then instructed to re-contour the same case/images (Scan2). Observer variation was analyzed volumetrically using conformation number (CN, where CN=1 equals a total agreement).
Results
In 14 evaluable contour sets (1 expert, 7 Group_A, 6 Group_B), there was greater agreement for GTV (mean CN 0.75) than CTVs (mean CN 0.46–0.65). Atlas exposure for Group_A led to a significant increased inter-observer agreement for CTVA (mean initial CN 0.68, post-atlas 0.76; p=0.03), as well as increased agreement with the expert reference (initial mean CN 0.58, 0.69 post-atlas; p=0.02). For GTV and CTVB, neither inter-observer nor expert agreement was altered after atlas exposure.
Conclusion
Consensus guideline atlas implementation resulted in a detectable difference in inter-observer agreement and greater approximation of expert volumes for CTVA, but not GTV or CTVB, in the specified case. Visual atlas inclusion should be considered as a feature in future clinical trials incorporating conformal radiotherapy.
BACKGROUND: Geographic barriers and limited availability of cancer specialists may influence early prostate cancer treatment options for rural men. This study compares receipt of different early prostate cancer treatments between rural and urban patients. METHODS: Using 2004-2006 SEER Limited-Use Data, 51,982 early prostate cancer patients were identified (T1c, T2a, T2b, T2c, T2NOS; no metastases) who were most likely to benefit from definitive treatment (< 75 years old, Gleason score < 8, PSA 20). Definitive treatment included radical prostatectomy, daily external beam radiation for 5 to 8 weeks, brachytherapy, or combination external beam radiation/brachytherapy. Adjusted definitive treatment rates were calculated by rural-urban residence overall, and for different sociodemographic and cancer characteristics, and different states based on logistic regression analyses, using general estimating equation methods to account for clustering by county. RESULTS: Adjusted definitive treatment rates were lower for rural (83.7%) than urban (87.1%) patients with early-stage prostate cancer (P .01). Rural men were more likely than urban men to receive nondefinitive surgical treatment and no initial treatment. The lowest definitive treatment rates were among rural subgroups: 70 to 74 years (73.9%), African Americans (75.6%), American Indians/Alaska Natives (77.8%), single/separated/divorced (76.8%), living in New Mexico (69.3%), and living in counties with persistent poverty (79.6%). CONCLUSIONS: Between 2004 and 2006, this adjusted analysis found that men who were living in rural areas were less likely to receive definitive treatment for their early-stage prostate cancer than those living in urban areas. Certain rural patient groups with prostate cancer need particular attention to ensure their access to appropriate treatment. Rural providerss, rural health care systems, and cancer advocacy and support organizations should ensure resources are in place so that the most vulnerable rural groups (men between 60 and 74 years of age; African American men; men who are single, separated, or divorced; and men living in rural New Mexico) can make informed prostate cancer treatment choices based on their preferences. Cancer 2013;119:3067-75.
The increasing interest in combined positron emission tomography (PET) and computed tomography (CT) to guide lung cancer radiation therapy planning has been well documented. Motion management strategies during treatment simulation PET/CT imaging and treatment delivery have been proposed to improve the precision and accuracy of radiotherapy. In light of these research advances, why has translation of motion‐managed PET/CT to clinical radiotherapy been slow and infrequent? Solutions to this problem are as complex as they are numerous, driven by large inter‐patient variability in tumor motion trajectories across a highly heterogeneous population. Such variation dictates a comprehensive and patient‐specific incorporation of motion management strategies into PET/CT‐guided radiotherapy rather than a one‐size‐fits‐all tactic. This review summarizes challenges and opportunities for clinical translation of advances in PET/CT‐guided radiotherapy, as well as in respiratory motion‐managed radiotherapy of lung cancer. These two concepts are then integrated into proposed patient‐specific workflows that span classification schemes, PET/CT image formation, treatment planning, and adaptive image‐guided radiotherapy delivery techniques.
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