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Is a Clinical Target Volume (CTV) Necessary in the Treatment of Lung Cancer in the Modern Era Combining 4-D Imaging and Image-guided Radiotherapy (IGRT)?

Kilburn JM, Lucas JT, Soike MH, Ayala-Peacock DN, Blackstock AW, Hinson WH, Munley MT, Petty WJ, Urbanic JJ - Cureus (2016)

Bottom Line: Median follow-up was 12 months, median OS was 22 months (95% CI 19-30 months), and LRC at two years was 69%.Fourteen local and eight regional events were scored with two CTVretro failures equating to a two-year CTV failure-free survival of 98%.Omission of a 1 cm CTV expansion appears feasible based on only two events among 110 patients and should be considered in radiation planning.

View Article: PubMed Central - HTML - PubMed

Affiliation: Radiation Oncology, Wake Forest School of Medicine.

ABSTRACT

Objective: We hypothesized that omission of clinical target volumes (CTV) in lung cancer radiotherapy would not compromise control by determining retrospectively if the addition of a CTV would encompass the site of failure.

Methods: Stage II-III patients were treated from 2009-2012 with daily cone-beam imaging and a 5 mm planning target volume (PTV) without a CTV. PTVs were expanded 1 cm and termed CTVretro. Recurrences were scored as 1) within the PTV, 2) within CTVretro, or 3) outside the PTV. Locoregional control (LRC), distant control (DC), progression-free survival (PFS), and overall survival (OS) were estimated.

Result: Among 110 patients, Stage IIIA 57%, IIIB 32%, IIA 4%, and IIB 7%. Eighty-six percent of Stage III patients received chemotherapy. Median dose was 70 Gy (45-74 Gy) and fraction size ranged from 1.5-2.7 Gy. Median follow-up was 12 months, median OS was 22 months (95% CI 19-30 months), and LRC at two years was 69%. Fourteen local and eight regional events were scored with two CTVretro failures equating to a two-year CTV failure-free survival of 98%.

Conclusion: Omission of a 1 cm CTV expansion appears feasible based on only two events among 110 patients and should be considered in radiation planning.

No MeSH data available.


Related in: MedlinePlus

Schematic of CTV creation for analysis1A) Creation of CTVretro for documentation of failures as PTV, CTV, or extended. 1B) Patient with documented CTV failure.
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FIG1: Schematic of CTV creation for analysis1A) Creation of CTVretro for documentation of failures as PTV, CTV, or extended. 1B) Patient with documented CTV failure.

Mentions: Each local and regional failure was individually reviewed by two physicians, including the principal investigator. Using MIM® Software, v5.6 (MIM Software Inc, Cleveland, OH), the simulation CT was co-registered and fused with the PET/CT or chest CT where relapse was documented for each local and regional failure. A 1 cm uniform expansion from the PTV was then retrospectively applied and termed CTVretro. Normal anatomical contours, target volumes (including the CTVretro), and isodose curves were overlaid onto the new CT. For each local and regional relapse, isodose curves, the original PTV contour, and the CTVretro contour were compared against the location of relapse and scored in one of three categories: 1) within the PTV (PTV failure), 2) outside the PTV but within the CTVretro (CTV failure), or 3) more than 1 cm from the PTV (extended failure). A patient was deemed to have a CTV failure if the CTVretro expansion would have encompassed the site of relapse, which was hypothesized to represent the scenario where a CTV could have theoretically prevented relapse. An illustration of how the CTVretro was created and of a patient experiencing a CTV failure is depicted in Figure 1.


Is a Clinical Target Volume (CTV) Necessary in the Treatment of Lung Cancer in the Modern Era Combining 4-D Imaging and Image-guided Radiotherapy (IGRT)?

Kilburn JM, Lucas JT, Soike MH, Ayala-Peacock DN, Blackstock AW, Hinson WH, Munley MT, Petty WJ, Urbanic JJ - Cureus (2016)

Schematic of CTV creation for analysis1A) Creation of CTVretro for documentation of failures as PTV, CTV, or extended. 1B) Patient with documented CTV failure.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4764420&req=5

FIG1: Schematic of CTV creation for analysis1A) Creation of CTVretro for documentation of failures as PTV, CTV, or extended. 1B) Patient with documented CTV failure.
Mentions: Each local and regional failure was individually reviewed by two physicians, including the principal investigator. Using MIM® Software, v5.6 (MIM Software Inc, Cleveland, OH), the simulation CT was co-registered and fused with the PET/CT or chest CT where relapse was documented for each local and regional failure. A 1 cm uniform expansion from the PTV was then retrospectively applied and termed CTVretro. Normal anatomical contours, target volumes (including the CTVretro), and isodose curves were overlaid onto the new CT. For each local and regional relapse, isodose curves, the original PTV contour, and the CTVretro contour were compared against the location of relapse and scored in one of three categories: 1) within the PTV (PTV failure), 2) outside the PTV but within the CTVretro (CTV failure), or 3) more than 1 cm from the PTV (extended failure). A patient was deemed to have a CTV failure if the CTVretro expansion would have encompassed the site of relapse, which was hypothesized to represent the scenario where a CTV could have theoretically prevented relapse. An illustration of how the CTVretro was created and of a patient experiencing a CTV failure is depicted in Figure 1.

Bottom Line: Median follow-up was 12 months, median OS was 22 months (95% CI 19-30 months), and LRC at two years was 69%.Fourteen local and eight regional events were scored with two CTVretro failures equating to a two-year CTV failure-free survival of 98%.Omission of a 1 cm CTV expansion appears feasible based on only two events among 110 patients and should be considered in radiation planning.

View Article: PubMed Central - HTML - PubMed

Affiliation: Radiation Oncology, Wake Forest School of Medicine.

ABSTRACT

Objective: We hypothesized that omission of clinical target volumes (CTV) in lung cancer radiotherapy would not compromise control by determining retrospectively if the addition of a CTV would encompass the site of failure.

Methods: Stage II-III patients were treated from 2009-2012 with daily cone-beam imaging and a 5 mm planning target volume (PTV) without a CTV. PTVs were expanded 1 cm and termed CTVretro. Recurrences were scored as 1) within the PTV, 2) within CTVretro, or 3) outside the PTV. Locoregional control (LRC), distant control (DC), progression-free survival (PFS), and overall survival (OS) were estimated.

Result: Among 110 patients, Stage IIIA 57%, IIIB 32%, IIA 4%, and IIB 7%. Eighty-six percent of Stage III patients received chemotherapy. Median dose was 70 Gy (45-74 Gy) and fraction size ranged from 1.5-2.7 Gy. Median follow-up was 12 months, median OS was 22 months (95% CI 19-30 months), and LRC at two years was 69%. Fourteen local and eight regional events were scored with two CTVretro failures equating to a two-year CTV failure-free survival of 98%.

Conclusion: Omission of a 1 cm CTV expansion appears feasible based on only two events among 110 patients and should be considered in radiation planning.

No MeSH data available.


Related in: MedlinePlus