Stage is not a reliable indicator of tumor volume in non-small cell lung cancer: a preliminary analysis of the Trans-Tasman Radiation Oncology Group 99-05 database.
BACKGROUND
Tumor volume has been shown to be a prognostic factor for the response of some tumors to radiotherapy. TNM stage has prognostic value for patients treated surgically for non-small cell lung cancer (NSCLC), but its value is less clear for patients treated by nonsurgical means. This may be because tumor size is not a consistent determinant of T stage or stage group. As part of the preliminary analyses for the Trans-Tasman Radiation Oncology Group 99-05 study, the authors performed this analysis to determine to what extent stage reflects tumor volume.


METHODS
In this prospective multicenter observational study, patients had to have histologically proven NSCLC, no evidence of disease beyond the primary site or thoracic lymph nodes, and been planned for radical radiotherapy with or without chemotherapy. Tumor volume measurements were based on computed tomography-based treatment planning images.


RESULTS
Four hundred four patients were available for analysis. There was a strong correlation between (log) maximum tumor diameter and (log) tumor volume (r = 0.93, p < 0.001). Although there was a highly significant trend of increasing volume with increasing T stage and stage group, when tumors were categorized into four groups according to increasing volume, there was only 55% concordance with T stage and 67% concordance with stage group.


CONCLUSIONS
There is limited correlation between tumor size and disease stage in patients with NSCLC. This justifies documentation and investigation of size as a potential prognostic factor independent of stage. Maximum tumor diameter may be an adequate substitute for volume as a measurement of size.
Ball
David L
DL
Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia. david.ball@petermac.org
Fisher
Richard
R
Burmeister
Bryan
B
Graham
Peter
P
Joseph
David
D
Penniment
Michael
M
Krawitz
Hedley
H
Wheeler
Greg
G
Poulsen
Michael
M
Vinod
Shalini
S
McClure
Bev
B
D000368:Aged; D002289:Carcinoma, Non-Small-Cell Lung / Q000473:pathology* / Q000532:radiotherapy; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000473:pathology* / Q000532:radiotherapy; D008207:Lymphatic Metastasis; D008297:Male; D009367:Neoplasm Staging; D011379:Prognosis; D047368:Tumor Burden