Recent advances in the biology of small cell lung cancer

Extrapulmonary and pulmonary small-cell carcinoma: tumor biology, therapy, and outcome

Extrapulmonary small-cell cancer is a distinct clinicopathological entity from small-cell anaplastic carcinoma of the lung. Approximately 1,000 cases have been projected annually in the United States, which represents an overall incidence of between 0.1% and 0.4% of all cancer. Not surprisingly then, little information is available regarding the treatment of this disease, which presents a challenge to the clinician when it is regionally confined. The majority of patients with extrapulmonary small-cell neoplasms have only been treated with local modalities of therapy, surgery, radiation, or a combination of both. Prolonged survival is not infrequent, which is in contrast to the experience for small-cell lung cancer and surprising given our current systemic approach to patients with this disease. This report will summarize the similarities and differences in biology, natural history, and clinical characteristics of patients with extrapulmonary small-cell cancer and small-cell anaplastic carcinoma of the lung. The histogenesis of small-cell cancer is briefly reviewed. A general therapeutic approach to patients with small-cell lung cancer is reported. Lastly, recommendations for therapy of patients with regionally confined extrapulmonary small-cell cancer by primary site are outlined.

Combination chemotherapy with or without radiation therapy in small cell lung cancer. An analysis of a 5-year follow-up

From January 1978 to March 1984, a series of 159 patients with newly diagnosed small cell lung cancer (SCLC) was treated with combination chemotherapy with or without chest radiation at the Osaka Prefectural Habikino Hospital. By March 31, 1989, ten patients (6.3%) had survived for 5 years or more after the initial chemotherapy, including nine of 95 patients (9.5%) with limited disease and one of 64 patients (1.6%) with extensive disease. All these 5-year disease-free survivors, except for one patient whose response could not be assessed by chest radiograph because of radiation fibrosis, had a complete response. Nine of the 71 patients (12.7%) treated with combination regimens containing doxorubicin survived 5 years or more, and only one of the 88 (1.1%) treated with regimens without doxorubicin had long-term survival (P less than 0.01). The sex, performance status (PS), and chest radiation after systemic chemotherapy did not correlate statistically with long-term survival (P greater than 0.05). Three of the ten patients died free of SCLC. Two of the ten patients (20%) developed second malignancies and died. The remaining patient died of pneumonia. The Cox regression analysis identified the PS and doxorubicin-containing regimens as important factors indicating improved survival. Combination regimens containing doxorubicin have, therefore, been found to be very effective in improving survival and achieving long-term survival.

Clinical biochemistry of neuron specific enolase

The soluble brain protein 14-3-2 first described by Moore and McGregor in 1965 is now known to be a cell specific isoenzyme of the glycolytic enzyme enolase (EC 4.2.1.11), designated neuron specific enolase (NSE). It is not only a marker for all types of neurons, but also for all neuroendocrine or paraneuronal cells. The appearance of NSE is a late event in neural differentiation, thus making NSE a useful index of neural maturation. The demonstration that tumors of the nervous system and of neuroendocrine origin contain NSE has promoted the study of NSE as a possible tumor marker. Immunocytochemistry has been used to identify NSE in cytologic preparations from several types of tumors, offering useful indications for differential diagnosis. NSE levels in serum from tumor patients are not useful in the diagnosis of early stage disease. However, serum NSE levels have been shown to be helpful in the identification of advanced small cell lung cancer, neuroblastoma and several other neoplasms. The main use of serum NSE is the monitoring of chemotherapy and the detection of a relapse in these cases.

Three-year disease-free survivors of small cell lung cancer treated with combination chemotherapy with or without chest irradiation

One hundred and seventy-four patients with small cell lung cancer (SCLC) treated with combination chemotherapy, with or without chest radiation, were analyzed. Fourteen patients (8%) survived for 3 years or more. Three-year disease-free survival continued for 12 of the 101 patients (12%) with limited disease, and one of 75 (1%) with extensive disease (P less than 0.05). Patients' sex and performance status were not important in achieving long-term survival. All disease-free survivors, except two who could not be evaluated, achieved a complete response. Although the treatment programs had some influence on the long-term survival rates (P less than 0.05), thoracic radiation did not have significant impact on long-term survival. Three of the 13 patients (23%) developed second malignancies and died, and one of these patients also suffered from a progressive neurologic deterioration with dementia. Two other patients died free of SCLC. Consequently, eight have remained alive and free of disease. The last relapse was observed at 1.5 years from beginning of treatment. The disease-free survival may offer the hope of cure of SCLC. However, the survivors are at an increased risk of developing late complications including second malignancies and neurologic abnormalities. Therefore, careful follow-up will be necessary.