The impact of abdominal computerized tomography on the pretreatment staging and prognosis of small cell lung cancer

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Abstract
One hundred six patients with small cell lung cancer (SCLC) were prospectively evaluated with regard to the prognostic impact of abdominal CT-scan in the pretreatment staging when compared to ultrasonography of the abdomen. Staging based on abdominal ultrasonography (US) plus bilateral bone marrow examinations gave as a result that 47 patients had extensive disease (ED) (44%). Seventeen patients with proven ED at time of referral were not included in this study. Abdominal CT-scan was performed in 16 of the 106 patients. Thirty patients of these 16 patients (39%) were classified as having ED after staging including US, but abdominal metastases were disclosed in another ten patients at the subsequent CT-scan. Liver metastases seen in two patients at ultrasonography were overlooked on the CT-scans. Median survival of the 36 patients classified as having limited disease (LD) after both procedures was 458 days, which was significantly better compared to 330 days for the ten patients with stage migration from LD to ED based on CT-scan, (p < 0.05) and compared to 242 days in the 30 patients with ED demonstrated by both US and CT-scans (p < 0.05). The prognostic impact of the CT-scan was further investigated in a multivariate analysis (Cox). Stage disease, performance status, LDH and alkaline phosphatase were significant prognostic factors in a proportional hazards model based on the original 106 patients. Patients in the best prognostic group were characterized by LD, good performance status (0–1) and normal LDH and alkaline phosphatase serum values. This group consisted of 22 patients (21%). Seventeen of these patients had a CT-scan, after which five patients (29%) were downgraded from LD to ED. This downgrading significantly increased the influence of stage in a new Cox model. Correspondingly, the 2-year survival rate rose from 31% to 41%. It is concluded that abdominal CT-scanning is a more sensitive staging procedure in SCLC than ultrasonography. In prognostication this superiority is most important for patients in the good prognostic category, and CT-scans could therefore be restricted to the 20 percent of the patients belonging to this category.