Three-dimensional conformal radiation may deliver considerable dose of incidental nodal irradiation in patients with early stage node-negative non-small cell lung cancer when the tumor is large and centrally located.
OBJECTIVE
To determine the dose to regional nodal stations in patients with T1-3N0M0 non-small cell lung cancer (NSCLC) treated with three-dimensional conformal radiation therapy (3DCRT) without intentional elective nodal irradiation (ENI).


METHODS
Twenty-three patients with medically inoperable T1-3N0M0 NSCLC were treated with 3DCRT without ENI. Hilar and mediastinal nodal regions were contoured on planning CT. The prescription dose was normalized to 70 Gy. Equivalent uniform dose (EUD) and other dosimetric parameters (e.g., V40) were calculated for each nodal station.


RESULTS
The median EUD for the whole group ranged from 0.4 to 4.4 Gy for all elective nodal regions. Gross tumor volume (GTV) and the relationship between GTV and hilum were significantly correlated with irradiation dose to ipsilateral hilar nodal regions (P<.05). For patients with GTV>or=30.2 cm3 (diameter approximately 4 cm) and or having any overlap with hilum, the median EUDs were 9.6, 22.6, and 62.9 Gy for ipsilateral lower paratracheal, subcarinal, and ipsilateral hilar regions, respectively. The corresponding median V40 were 32.5%, 39.3%, and 97.6%, respectively.


CONCLUSIONS
Although incidental nodal irradiation dose is low in the whole group, the dose to high-risk nodal regions is considerable in patients with T1-3N0 NSCLC when the primary is large and/or centrally located.
Zhao
Lujun
L
Department of Radiation Oncology, University of Michigan Health System, Ann Arbor, MI 48109, USA.
Chen
Ming
M
Ten Haken
Randall
R
Chetty
Indrin
I
Chapet
Olivier
O
Hayman
James A
JA
Kong
Feng-Ming
FM
D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology* / Q000532:radiotherapy*; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology* / Q000532:radiotherapy*; D008198:Lymph Nodes / Q000528:radiation effects*; D009367:Neoplasm Staging; D011879:Radiotherapy Dosage; D020266:Radiotherapy, Conformal; D047368:Tumor Burden