Does 5 + 5 Equal Better Radiation Treatment Plans in Head and Neck Cancers?
Purpose: Accurate contouring in head and neck cancer (HNC) is critical. International consensus guidelines recommend the 5 + 5 mm rule for expansions around the primary tumor, wherein high- and low-dose clinical target volumes (CTV-P1 and CTV-P2, respectively) are created using successive 5 mm expan...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Elsevier
2019-10-01
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| Series: | Advances in Radiation Oncology |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S2452109419300624 |
| _version_ | 1828860841248686080 |
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| author | Mark T. Corkum, MD, MSc Sylvia Mitchell, MRT(T) Varagur Venkatesan, MBBS Nancy Read, MD Andrew Warner, MSc David A. Palma, MD, PhD |
| author_facet | Mark T. Corkum, MD, MSc Sylvia Mitchell, MRT(T) Varagur Venkatesan, MBBS Nancy Read, MD Andrew Warner, MSc David A. Palma, MD, PhD |
| author_sort | Mark T. Corkum, MD, MSc |
| collection | DOAJ |
| description | Purpose: Accurate contouring in head and neck cancer (HNC) is critical. International consensus guidelines recommend the 5 + 5 mm rule for expansions around the primary tumor, wherein high- and low-dose clinical target volumes (CTV-P1 and CTV-P2, respectively) are created using successive 5 mm expansions on the gross tumor volume. To our knowledge, the necessity of a low-dose CTV-P2 has never been assessed; therefore, we evaluated the dosimetric impact of adding a CTV-P2 expansion using the 5 + 5 mm rule compared with contouring with a high-dose CTV-P1 alone. Methods and materials: A retrospective study of clinically delivered (chemo)radiation therapy treatment plans for HNC was conducted. All patients were treated with 70 Gy in 35 fractions using volumetric modulated arc therapy in a single phase. CTV-P2 was retrospectively contoured per guidelines as a 5 mm expansion on CTV-P1 from the clinical plan, carving off specified barriers to spread. We used a 5 mm planning target volume (PTV) expansion. Our primary outcome was whether 95% of the volume of the PTV for the CTV-P2 contour (ie, PTV-P2) received at least 56 Gy. To assess dose falloff, the coverage of a PTV ring structure was created by subtracting PTV-P1 from PTV-P2. Results: Twenty-seven patients from 4 HNC subsites (base of tongue, tonsil, hypopharynx, and supraglottic larynx) were included. In all 108 treatment plans, at least 95% of the PTV-P2 structure received at least 56 Gy. The minimum volume of the PTV-P2 structure receiving at least 56 Gy was 97.4%. Eight of 108 treatment plans had borderline coverage of the PTV ring substructure alone. Conclusions: Adding a CTV-P2 structure using the 5 + 5 mm rule had no dosimetric impact, adds contouring time, adds treatment planning complexity, and could potentially introduce errors. The 5 + 5 mm rule may have value in other settings, such as when smaller PTV margins are used, and warrants further evaluation with prospective or randomized studies. |
| first_indexed | 2024-12-13T02:47:12Z |
| format | Article |
| id | doaj.art-d4f43e40ba9448b59b914750bb2fde2c |
| institution | Directory Open Access Journal |
| issn | 2452-1094 |
| language | English |
| last_indexed | 2024-12-13T02:47:12Z |
| publishDate | 2019-10-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Advances in Radiation Oncology |
| spelling | doaj.art-d4f43e40ba9448b59b914750bb2fde2c2022-12-22T00:02:09ZengElsevierAdvances in Radiation Oncology2452-10942019-10-0144683688Does 5 + 5 Equal Better Radiation Treatment Plans in Head and Neck Cancers?Mark T. Corkum, MD, MSc0Sylvia Mitchell, MRT(T)1Varagur Venkatesan, MBBS2Nancy Read, MD3Andrew Warner, MSc4David A. Palma, MD, PhD5Department of Radiation Oncology, London Health Sciences Centre, London, Ontario, CanadaDepartment of Radiation Oncology, London Health Sciences Centre, London, Ontario, CanadaDepartment of Radiation Oncology, London Health Sciences Centre, London, Ontario, CanadaDepartment of Radiation Oncology, London Health Sciences Centre, London, Ontario, CanadaDepartment of Radiation Oncology, London Health Sciences Centre, London, Ontario, CanadaCorresponding author.; Department of Radiation Oncology, London Health Sciences Centre, London, Ontario, CanadaPurpose: Accurate contouring in head and neck cancer (HNC) is critical. International consensus guidelines recommend the 5 + 5 mm rule for expansions around the primary tumor, wherein high- and low-dose clinical target volumes (CTV-P1 and CTV-P2, respectively) are created using successive 5 mm expansions on the gross tumor volume. To our knowledge, the necessity of a low-dose CTV-P2 has never been assessed; therefore, we evaluated the dosimetric impact of adding a CTV-P2 expansion using the 5 + 5 mm rule compared with contouring with a high-dose CTV-P1 alone. Methods and materials: A retrospective study of clinically delivered (chemo)radiation therapy treatment plans for HNC was conducted. All patients were treated with 70 Gy in 35 fractions using volumetric modulated arc therapy in a single phase. CTV-P2 was retrospectively contoured per guidelines as a 5 mm expansion on CTV-P1 from the clinical plan, carving off specified barriers to spread. We used a 5 mm planning target volume (PTV) expansion. Our primary outcome was whether 95% of the volume of the PTV for the CTV-P2 contour (ie, PTV-P2) received at least 56 Gy. To assess dose falloff, the coverage of a PTV ring structure was created by subtracting PTV-P1 from PTV-P2. Results: Twenty-seven patients from 4 HNC subsites (base of tongue, tonsil, hypopharynx, and supraglottic larynx) were included. In all 108 treatment plans, at least 95% of the PTV-P2 structure received at least 56 Gy. The minimum volume of the PTV-P2 structure receiving at least 56 Gy was 97.4%. Eight of 108 treatment plans had borderline coverage of the PTV ring substructure alone. Conclusions: Adding a CTV-P2 structure using the 5 + 5 mm rule had no dosimetric impact, adds contouring time, adds treatment planning complexity, and could potentially introduce errors. The 5 + 5 mm rule may have value in other settings, such as when smaller PTV margins are used, and warrants further evaluation with prospective or randomized studies.http://www.sciencedirect.com/science/article/pii/S2452109419300624 |
| spellingShingle | Mark T. Corkum, MD, MSc Sylvia Mitchell, MRT(T) Varagur Venkatesan, MBBS Nancy Read, MD Andrew Warner, MSc David A. Palma, MD, PhD Does 5 + 5 Equal Better Radiation Treatment Plans in Head and Neck Cancers? Advances in Radiation Oncology |
| title | Does 5 + 5 Equal Better Radiation Treatment Plans in Head and Neck Cancers? |
| title_full | Does 5 + 5 Equal Better Radiation Treatment Plans in Head and Neck Cancers? |
| title_fullStr | Does 5 + 5 Equal Better Radiation Treatment Plans in Head and Neck Cancers? |
| title_full_unstemmed | Does 5 + 5 Equal Better Radiation Treatment Plans in Head and Neck Cancers? |
| title_short | Does 5 + 5 Equal Better Radiation Treatment Plans in Head and Neck Cancers? |
| title_sort | does 5 5 equal better radiation treatment plans in head and neck cancers |
| url | http://www.sciencedirect.com/science/article/pii/S2452109419300624 |
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