Chest tumor response measurement during lung cancer chemotherapy. Comparison between computed tomography and standard roentgenography.

Chemotherapy of lung cancer has, until now, been an experimental approach that requires careful evaluation of tumor response. The growing number of lung cancer patients now undergoing chemotherapy has led to a rapid increase in the number of computed tomography (CT) scans performed. Eighty consecutive lung cancer patients (55 non-small cell and 25 small cell lung cancers) were included in a prospective study to analyze whether the standard chest roentgenography is as effective as computed tomography in evaluating tumor response. Both standard chest roentgenography and CT scanning were performed before the chemotherapy began and were repeated after 10 to 12 wk of treatment. Response evaluations were performed according to the World Health Organization recommendations. When two-dimensional measurements were possible, the Indicator lesions were defined as measurable tumors. Both roentgenography methods were used, independently, to classify the response into the following categories: complete response, partial response, minor response, stable disease, and progressive disease. A comparison of CT scans versus standard chest roentgenography as a measurement of indicator lesion showed a concordance of borderline significance (kappa = 0.146, p < 0.05); a significant asymmetry was demonstrated (McNemar = 35.6, p < 0.001), indicating that CT scanning may be a more appropriate method for measuring tumors than standard chest roentgenography. Moreover, no concordance was observed comparing CT scan and standard chest roentgenography measurability in the subgroups of patients with T3 or T4 tumor, hilar tumor, and patients with pleural effusion or atelectasis in which the McNemar test of symmetry constantly showed a better measurability using CT scan. The comparison of response classification given by the two roentgenography methods showed a concordance (kappa = 0.527, p < 0.01) without statistical asymmetry (McNemar = 4.5, NS). However, major discrepancies were observed In 22.5% of the patients in whom standard chest roentgenography would have led to a wrong therapeutic decision. With regard to the subgroup of 34 patients in whom two-dimensional tumor measurements using standard chest roentgenography were possible, a correlation was observed between the response calculated as a percentage of the initial measurements by means of chest roentgenography and that calculated using CT scan measurements (r = 0.97, p < 0.001). Moreover, when multiple indicator lesions could be defined on CT scan, a correlation was observed between the response calculated with only one indicator lesion and that obtained with two (r = 0.87, p < 0.001). We conclude that standard chest roentgenography measurements are poor inasmuch as they are affected by many common pretherapeutic features of advanced lung cancer (pleural effusion, T4, and atelectasis). A careful tumor response assessment requires measurement of indicator lesions using chest Cr scanning in almost all lung cancer patients during chemotherapy. However, in a subgroup of highly selected patients In whom a two-dimensional indicator lesion could be assessed on standard chest roentgenography, the analyzed response correlated well with that assessed by CT scan.