Effect of radiologic stage III substage on nonsurgical therapy of non-small cell lung cancer

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Abstract
Background. Patients with Stage III non–small cell lung cancer (NSCLC) whose cases are staged or treated surgically have different prognoses, depending on the substage (IIIa, IIIb). It is not known whether the prognostic differences apply to clinically staged nonsurgical cases. The authors wanted to determine whether radiologic Stage III substages, determined by computerized axial tomography (CT) scans, are prognostically important in these patients with NSCLC. In addition, they wanted to determine whether the observed superior survival of selected patients with Stage III NSCLC receiving chemotherapy in addition to radiation therapy (chemo‐RT) (Cancer and Leukemia Group B protocol 8433: N Engl J Med 1990; 323:940–5) was influenced by an imbalance in the radiologic Stage III substage. Methods. Review of pretreatment chest radiographs and CT scans with determination of TNM status and stage was done by the consensus of three readers, who were unaware of which treatment each patient had received (radiation therapy alone [RT] or chemo‐RT). Results. Patient characteristics in the two treatment arms were similar. Fifty‐five percent of patients receiving RT had Stage IIIa and 33% Stage IIIb disease; in the chemo‐RT treatment arm, 73% had Stage IIIa and 25% Stage IIIb disease (P = 0.11). Seven patients (12%) who received RT and one in the chemo‐RT treatment arm (2%) had Stage I–II disease on CT scan. Patients with Stage IIIa disease had superior survival to those with Stage IIIb disease (median, 16.5 versus 10.5 months, respectively; P = 0.0045). Within each substage, survival was superior in the chemo‐RT (versus RT) treatment arm (Stage IIIa, 17.2 versus 10.7 months, respectively; P = 0.16; Stage IIIb, 12.0 versus 6.9 months, respectively; P = 0.089). Conclusions. The survival advantage for selected patients with Stage III NSCLC treated with chemo‐RT in this study did not result from a more favorable pretreatment radiologic Stage III substage. An advantage for induction chemotherapy was seen in patients with Stage IIIa and IIIb disease. Future studies in this population should prospectively assess and consider stratification for Stage III substage.