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Three-dimensional conformal radiation for esophageal squamous cell carcinoma with involved-field irradiation may deliver considerable doses of incidental nodal irradiation.

Ji K, Zhao L, Yang C, Meng M, Wang P - Radiat Oncol (2012)

Bottom Line: The equivalent uniform dose (EUD) and other dosimetric parameters were calculated for each nodal station.Nodal regions with a metastasis rate greater than 5% were considered a high-risk lymph node subgroup.In the regions with an EUD less than 40 Gy, most incidental irradiation doses were significantly associated with esophageal tumor length and location.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Radiotherapy, Tianjin Medical University Cancer Institute and Hospital, and Tianjin Key Laboratory of Cancer Prevention and Therapy, Tianjin, PR China.

ABSTRACT

Background: To quantify the incidental irradiation dose to esophageal lymph node stations when irradiating T1-4N0M0 thoracic esophageal squamous cell carcinoma (ESCC) patients with a dose of 60 Gy/30f.

Methods: Thirty-nine patients with medically inoperable T1-4N0M0 thoracic ESCC were treated with three-dimensional conformal radiation (3DCRT) with involved-field radiation (IFI). The conformal clinical target volume (CTV) was re-created using a 3-cm margin in the proximal and distal direction beyond the barium esophagogram, endoscopic examination and CT scan defined the gross tumor volume (GTV) and a 0.5-cm margin in the lateral and anteroposterior directions of the CT scan-defined GTV. The PTV encompassed 1-cm proximal and distal margins and 0.5-cm radial margin based on the CTV. Nodal regions were delineated using the Japanese Society for Esophageal Diseases (JSED) guidelines and an EORTC-ROG expert opinion. The equivalent uniform dose (EUD) and other dosimetric parameters were calculated for each nodal station. Nodal regions with a metastasis rate greater than 5% were considered a high-risk lymph node subgroup.

Results: Under a 60 Gy dosage, the median D mean and EUD was greater than 40 Gy in most high-risk nodal regions except for regions of 104, 106tb-R in upper-thoracic ESCC and 101, 104-R, 105, 106rec-L, 2, 3&7 in middle-thoracic ESCC and 107, 3&7 in lower-thoracic ESCC. In the regions with an EUD less than 40 Gy, most incidental irradiation doses were significantly associated with esophageal tumor length and location.

Conclusions: Lymph node stations near ESCC receive considerable incidental irradiation doses with involved-field irradiation that may contribute to the elimination of subclinical lesions.

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Related in: MedlinePlus

Relationship between the PTV length located in the cervical esophagus and incidental irradiation dose to region 104 of upper-thoracic ESCC. EUD, equivalent uniform dose.
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Figure 1: Relationship between the PTV length located in the cervical esophagus and incidental irradiation dose to region 104 of upper-thoracic ESCC. EUD, equivalent uniform dose.

Mentions: For the 104 and 106tb-R subgroups of high-risk nodal regions in upper-thoracic ESCC, the median EUD was only 1517.6 and 3638.2 cGy, although the median Dmean reached 4169.4 and 4606.8 cGy. However, the incidental irradiation dose of these two regions was significantly associated with the length and location of the esophageal tumor. For region 104, the incidental irradiation dose was significantly associated with the length of PTV located in the cervical esophagus (Figure 1) and the correlation coefficient (r) and P values of Dmean were 0.696 and 0.012, respectively. Similarly, for EUD of region 104, the r and p values were 0.732 and 0.007, respectively. In addition, the incidental irradiation dose of 106tb-R was significantly associated with the length of PTV located in the middle-thoracic esophagus (Figure 2). For Dmean, the r and p values were 0.733 and 0.007, respectively. The values of r and p were 0.835 and 0.001 for EUD, respectively. In addition, V40 and V50 values of all high-risk nodal regions of upper-thoracic ESCC, except 104 and 106tb-R, were greater than 85% and 70%, respectively.


Three-dimensional conformal radiation for esophageal squamous cell carcinoma with involved-field irradiation may deliver considerable doses of incidental nodal irradiation.

Ji K, Zhao L, Yang C, Meng M, Wang P - Radiat Oncol (2012)

Relationship between the PTV length located in the cervical esophagus and incidental irradiation dose to region 104 of upper-thoracic ESCC. EUD, equivalent uniform dose.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3585467&req=5

Figure 1: Relationship between the PTV length located in the cervical esophagus and incidental irradiation dose to region 104 of upper-thoracic ESCC. EUD, equivalent uniform dose.
Mentions: For the 104 and 106tb-R subgroups of high-risk nodal regions in upper-thoracic ESCC, the median EUD was only 1517.6 and 3638.2 cGy, although the median Dmean reached 4169.4 and 4606.8 cGy. However, the incidental irradiation dose of these two regions was significantly associated with the length and location of the esophageal tumor. For region 104, the incidental irradiation dose was significantly associated with the length of PTV located in the cervical esophagus (Figure 1) and the correlation coefficient (r) and P values of Dmean were 0.696 and 0.012, respectively. Similarly, for EUD of region 104, the r and p values were 0.732 and 0.007, respectively. In addition, the incidental irradiation dose of 106tb-R was significantly associated with the length of PTV located in the middle-thoracic esophagus (Figure 2). For Dmean, the r and p values were 0.733 and 0.007, respectively. The values of r and p were 0.835 and 0.001 for EUD, respectively. In addition, V40 and V50 values of all high-risk nodal regions of upper-thoracic ESCC, except 104 and 106tb-R, were greater than 85% and 70%, respectively.

Bottom Line: The equivalent uniform dose (EUD) and other dosimetric parameters were calculated for each nodal station.Nodal regions with a metastasis rate greater than 5% were considered a high-risk lymph node subgroup.In the regions with an EUD less than 40 Gy, most incidental irradiation doses were significantly associated with esophageal tumor length and location.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Radiotherapy, Tianjin Medical University Cancer Institute and Hospital, and Tianjin Key Laboratory of Cancer Prevention and Therapy, Tianjin, PR China.

ABSTRACT

Background: To quantify the incidental irradiation dose to esophageal lymph node stations when irradiating T1-4N0M0 thoracic esophageal squamous cell carcinoma (ESCC) patients with a dose of 60 Gy/30f.

Methods: Thirty-nine patients with medically inoperable T1-4N0M0 thoracic ESCC were treated with three-dimensional conformal radiation (3DCRT) with involved-field radiation (IFI). The conformal clinical target volume (CTV) was re-created using a 3-cm margin in the proximal and distal direction beyond the barium esophagogram, endoscopic examination and CT scan defined the gross tumor volume (GTV) and a 0.5-cm margin in the lateral and anteroposterior directions of the CT scan-defined GTV. The PTV encompassed 1-cm proximal and distal margins and 0.5-cm radial margin based on the CTV. Nodal regions were delineated using the Japanese Society for Esophageal Diseases (JSED) guidelines and an EORTC-ROG expert opinion. The equivalent uniform dose (EUD) and other dosimetric parameters were calculated for each nodal station. Nodal regions with a metastasis rate greater than 5% were considered a high-risk lymph node subgroup.

Results: Under a 60 Gy dosage, the median D mean and EUD was greater than 40 Gy in most high-risk nodal regions except for regions of 104, 106tb-R in upper-thoracic ESCC and 101, 104-R, 105, 106rec-L, 2, 3&7 in middle-thoracic ESCC and 107, 3&7 in lower-thoracic ESCC. In the regions with an EUD less than 40 Gy, most incidental irradiation doses were significantly associated with esophageal tumor length and location.

Conclusions: Lymph node stations near ESCC receive considerable incidental irradiation doses with involved-field irradiation that may contribute to the elimination of subclinical lesions.

Show MeSH
Related in: MedlinePlus