title: Stereological Evaluation of Tumor Regression Rates in Lung Cancer Using CT Via the Cavalieri Method.
abstract: OBJECTIVE
  The aims of this study were to analyze the relevant methods of computed tomography (CT) and stereology with respect to the estimation of tumor volume and to determine whether the response rates measured by the stereological method correlate with those of conventional morphometric techniques in lung cancer.
  
  
  METHODS
  The study group was composed of 32 patients, including 25 males and 7 females. All the subjects included were non-small celled lung cancer patients (NSCLC), and they were all treated with either chemotherapy (n=12) or chemotherapy plus radiotherapy (n=20) for locally advanced disease (Stage III A and Stage III B). All patients underwent contrast enhanced CT of the thorax before and after treatment. Tumor diameters were measured according to stereological methods, the World Health Organization (WHO) criteria and the Response Evaluation Criteria in Solid Tumors (RECIST).
  
  
  RESULTS
  With all three methods (stereological method, RECIST and WHO), an improvement was observed in the mean tumor size. The response rates were 11.8 ± 117.5% (stereological method), 27.4 ± 38.8% (RECIST), and 38.7 ± 68.1% (WHO). Although the response rates in RECIST and WHO criteria were statistically significant (P=0.02 and P=0.045 for RECIST and WHO, respectively), the response rates with stereological measurements were not statistically significant (P=0.21), showing that response rates obtained by the Cavalieri method differ from those obtained through WHO and RECIST. The comparison between response rates obtained with each method shows that the stereological response rate was not correlated with the response rate in either RECIST or WHO, (r=-0.15, P=0.59 and r=-0.27, P=0.33 for RECIST and WHO, respectively), while there was good correlation between the WHO and RECIST response rates (r=0.87 and P<0.001).
  
  
  CONCLUSIONS
  The Cavalieri principle is more suitable for the evaluation of tumor volumes in response to treatment in the management of advanced malignancies, in particular in patients with tumors of irregular shape or when the determination of treatment response is not clear.
authors.affiliation: Atatürk University, Faculty of Medicine, Department of Chest Disease, Erzurum, Turkey.
authors.forename: Metin
authors.initials: M
authors.lastname: Akgun
authors.affiliation: Atatürk University, Faculty of Medicine, Department of Radiology, Erzurum, Turkey.
authors.forename: Mecit
authors.initials: M
authors.lastname: Kantarci
authors.affiliation: Atatürk University, Faculty of Medicine, Department of Medical Oncology, Erzurum, Turkey.
authors.forename: Kerim
authors.initials: K
authors.lastname: Cayir
authors.affiliation: Atatürk University, Faculty of Medicine, Department of Radiology, Erzurum, Turkey.
authors.forename: Ummugulsum
authors.initials: U
authors.lastname: Bayraktutan
authors.affiliation: Numune Hospital, Department of Radiology, Erzurum, Turkey.
authors.forename: Selim
authors.initials: S
authors.lastname: Doganay
authors.affiliation: Atatürk University, Faculty of Medicine, Department of Chest Disease, Erzurum, Turkey.
authors.forename: Omer
authors.initials: O
authors.lastname: Araz
authors.affiliation: Atatürk University, Faculty of Medicine, Department of Histology and Embryology, Erzurum, Turkey.
authors.forename: Eyup
authors.initials: E
authors.lastname: Altunkaynak
authors.affiliation: Atatürk University, Faculty of Medicine, Department of Medical Oncology, Erzurum, Turkey.
authors.forename: Mehmet
authors.initials: M
authors.lastname: Bilici
authors.affiliation: Atatürk University, Faculty of Medicine, Department of Histology and Embryology, Erzurum, Turkey.
authors.forename: Bunyami
authors.initials: B
authors.lastname: Unal
authors.affiliation: Atatürk University, Faculty of Medicine, Department of Chest Disease, Erzurum, Turkey.
authors.forename: Metin
authors.initials: M
authors.lastname: Gorguner
keywords: Computerized tomography; Lung cancer; Stereology; Volume measurement