Rectal and bladder deformation and displacement during preoperative radiotherapy for rectal cancer: Are current margin guidelines adequate for conformal therapy?

Assessment and clinical validation of margins for adaptive simultaneous integrated boost in neo-adjuvant radiochemotherapy for rectal cancer

“…Daly et al [22] evaluated rectal motion for 17 rectal cancer patients through the analysis of 39 CBCTs. They found that an anterior margin of 1.5 cm ensures that the target remains within the prescription dose.…”

Target Volume Delineation for Conformal and Intensity-Modulated Radiation Therapy

“…Any visible mesorectal nodes on CT and PET should also be included To cover the iliac lymphatics, a 0.7-cm margin around the iliac vessels should be drawn (excluding the muscle and bone) (Myerson et al 2009 ;Taylor et al 2005 ) To cover the external iliac nodes, an additional 1-cm margin anterolaterally around the vessels is needed. Any adjacent small nodes should be included (Myerson et al 2009 ;Taylor et al 2005 ) Anteriorly, a margin of 1-1.5 cm should be added into bladder to account for changes in bladder and rectal fi lling (Myerson et al 2009 ;Daly et al 2011 ) A 1.8-cm-wide volume between the external and internal iliac vessels is needed to cover the obturator nodes (Taylor et al 2005 ) CTV-standard risk (CTV-SR) Should cover the entire mesorectum and right and left internal iliac lymph nodes for T3 tumors. The right and left external iliac lymph nodes for T4 tumors with anterior organ involvement should also be included A 1-2-cm margin in adjacent organs with gross tumor invasion should be added for T4 lesions Superiorly, the entire rectum and mesorectum should be included (usually up to L5/S1) and at least 2-cm margin superior to gross disease, whichever is most cephalad Inferiorly, the CTV should extend to the pelvic fl oor or at least 2 cm below the gross disease, whichever is most caudad To cover the iliac lymphatics, a 0.7-cm margin around the internal iliac vessels should be drawn (excluding the muscle and bone) (Myerson et al 2009 ;Taylor et al 2005 ) To cover the external iliac nodes (for T4 lesions), an additional 1-cm margin anterolaterally around the vessels is needed.…”

“…The right and left external iliac lymph nodes for T4 tumors with anterior organ involvement should also be included A 1-2-cm margin in adjacent organs with gross tumor invasion should be added for T4 lesions Superiorly, the entire rectum and mesorectum should be included (usually up to L5/S1) and at least 2-cm margin superior to gross disease, whichever is most cephalad Inferiorly, the CTV should extend to the pelvic fl oor or at least 2 cm below the gross disease, whichever is most caudad To cover the iliac lymphatics, a 0.7-cm margin around the internal iliac vessels should be drawn (excluding the muscle and bone) (Myerson et al 2009 ;Taylor et al 2005 ) To cover the external iliac nodes (for T4 lesions), an additional 1-cm margin anterolaterally around the vessels is needed. Any adjacent small nodes should be included (Myerson et al 2009 ;Taylor et al 2005 ) Anteriorly, a margin of 1-1.5 cm should be added into bladder to account for changes in bladder and rectal fi lling (Myerson et al 2009 ;Daly et al 2011 ) A 1.8-cm-wide volume between the external and internal iliac vessels is needed to cover the obturator nodes (Taylor et al 2005 ) Planning target volume (PTV) Each CTV should be expanded by 0.5-1 cm, depending on the physician's comfort level with setup accuracy, frequency of imaging, and the use of IGRT…”

“…Any adjacent small nodes should be included (Myerson et al 2009 ;Taylor et al 2005 ) Anteriorly, a margin of 1-1.5 cm should be added into bladder to account for changes in bladder and rectal fi lling (Myerson et al 2009 ;Daly et al 2011 ) A 1.8-cm-wide volume between the external and internal iliac vessels is needed to cover the obturator nodes (Taylor et al 2005 ) For tumors that extend inferiorly to or inferior to the dentate line, the bilateral inguinal nodes should be included Planning target volume (PTV) Each CTV should be expanded by 0.5-1 cm, depending on the physician's comfort level with setup accuracy, frequency of imaging, and the use of IGRT Inferior : inferior border should be 2 cm below gross disease. Should include the entire mesorectum down to the pelvic fl oor Lateral : Does not need to extend more than a few millimeters beyond the levator muscles unless there is tumor extension into the ischiorectal fossa.…”

“…The CTV-N should cover the GTV-N with a 1.0-1.5 cm margin but excluding uninvolved bone, muscle or air CTV-high risk (CTV-HR) Should cover the entire mesorectum, the right and left internal iliac lymph nodes inferior to the inferior-most level of the sacroiliac joint, and the inguinal or external iliac lymphatics if the inguinal nodes are uninvolved To cover the iliac lymphatics, a 0.7-cm margin around the iliac vessels should be drawn (excluding muscle and bone) (Myerson et al 2009 ;Taylor et al 2005 ) To cover the external iliac nodes, an additional 1 cm margin anterolaterally around the vessels is needed. Any adjacent small nodes should be included (Myerson et al 2009 ;Taylor et al 2005 ) Anteriorly, a margin of 1-1.5 cm should be added into the bladder to account for changes in the bladder and rectal fi lling (Myerson et al 2009 ;Daly et al 2011 ) A 1.8-cm wide volume between the external and internal iliac vessels is needed to cover the obturator nodes (Taylor et al 2005 ) CTV-low risk (CTV-LR) Should include the uninvolved inguinal, external iliac, and internal iliac nodes superior to the inferior-most level of the sacroiliac joint To cover the iliac lymphatics, a 0.7-cm margin around the iliac vessels should be drawn (excluding muscle and bone) (Myerson et al 2009 ;Taylor et al 2005 ) To cover the external iliac nodes, an additional 1 cm margin anterolaterally around the vessels is needed. Any adjacent small nodes should be included (Myerson et al 2009 ;Taylor et al 2005 ) Anteriorly, a margin of 1-1.5 cm should be added into bladder to account for changes in the bladder and rectal fi lling (Myerson et al 2009 ;Daly et al 2011 ) A 1.8-cm wide volume between the external and internal iliac vessels is needed to cover the obturator nodes (Taylor et al 2005 ) Planning target volume (PTV) Each CTV should be expanded by 0.5-1 cm, depending on the physician's comfort level with setup accuracy, frequency of imaging, and the use of IGRT Fig.…”