Intraindividual comparison of conventional three-dimensional radiotherapy and intensity modulated radiotherapy in the therapy of locally advanced non-small cell lung cancer a planning study.
BACKGROUND
Local failure is the one of the most frequent cause of tumor related death in locally advanced non-small cell lung cancer (LAD-NSCLC). Dose escalation has the promise of increased loco-regional tumor control but is limited by the tolerances of critical organs.


METHODS
To evaluate the potential of IMRT in comparison to conventional three-dimensional conformal planning (3DCRT) dose constraints were defined: Maximum dose (D(max)) to spinal cord < 48 Gy, mean lung dose </= 24 Gy, D(max) esophagus > 70 Gy in not more than 5 cm of the total length. For ten patients two plans were compared: (1) 3DCRT with 5 weekly fractions (SD) of 2 Gy to a total dose (TD) of 50 Gy to the planning target volume of second order (PTV2). If the tolerance of the critical organs was not exceeded, patients get a boost plan with a higher TD to the PTV1. (2) IMRT: concomitant boost with 5 weekly SD of 2 Gy (PTV1) and 1.5 Gy to a partial (p)PTV (pPTV=PTV2 profile of a line PTV1) to a TD of 51 Gy to the pPTV and 68 Gy to the PTV1. If possible, patients get a boost plan to the PTV1 with 5 weekly SD of 2 Gy to the highest possibly TD.


RESULTS
Using 3DCRT, 3/10 patients could not be treated with TD > 50 Gy, but 9/10 patients get higher TD by IMRT. TD to the PTV1 could be escalated by 16% on average. The use of non-coplanar fields in IMRT lead to a reduction of the irradiated lung volume. There is a strong correlation between physical and biological mean lung doses.


CONCLUSIONS
IMRT gives the possibility of further dose escalation without an increasing mean lung dose especially in patients with large tumors.
Marnitz
Simone
S
Klinik und Poliklinik für Strahlentherapie, Universitätsklinikum Charité Campus Mitte, Berlin, Germany. simone.marnitz@charite.de
Stuschke
Martin
M
Bohsung
Jörg
J
Moys
Anne
A
Reng
Ines
I
Wurm
Reinhard
R
Budach
Volker
V
D000328:Adult; D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology / Q000532:radiotherapy*; D019583:Dose Fractionation, Radiation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D021621:Imaging, Three-Dimensional; D008175:Lung Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D008297:Male; D008875:Middle Aged; D009367:Neoplasm Staging; D010043:Outcome and Process Assessment, Health Care; D011879:Radiotherapy Dosage; D011880:Radiotherapy Planning, Computer-Assisted; D011881:Radiotherapy, Computer-Assisted; D020266:Radiotherapy, Conformal; D014057:Tomography, X-Ray Computed