Small cell carcinoma: combined approach to treatment

Evaluation of Circulating Tumor Cells in Predicting Therapeutic Response in Small Cell Lung Cancer Patients

BACKGROUND AND AIMS

Circulating tumor cells (CTCs) have prognostic significance in patients with metastatic cancer, but their utility in predicting the response to tumor therapy is unknown. This study examined the correlation of CTCs with the therapeutic response in small cell lung cancer (SCLC).

METHODS

Clinical and pathological data from 96 SCLC patients were evaluated in this study. CellSearch kits were used to detect CTCs in peripheral blood samples. Statistical analysis was performed using Fisher exact test and Mann-Whitney U test.

RESULTS

At baseline, 47 (50.0%) SCLC patients had detectable CTC counts. Serum neuron-specific enolase (NSE) was found to be associated with CTC thresholds. However, no significant differences were observed for an association of any threshold CTC count with the treatment response, with gender, age (≤60 or >60 years), smoking status, syndrome of inappropriate antidiuretic hormone (SIADH), or Ki67 expression.

CONCLUSION

Detection of CTCs in SCLC patients was associated with serum NSE but not with response to cancer therapy.

Syndrome of inappropriate antidiuretic hormone secretion (SIADH) in patients with limited stage small cell lung cancer

A few series in the literature were published before 1987 on syndrome of inappropriate antidiuretic hormone secretion (SIADH) in small cell lung cancer (SCLC). This study examines the outcome in more recent era. From 1981-1998, there were 1417 new cases of SCLC diagnosed in the provincial registry, of which 244 were of limited stage (LS). A chart review and statistical analyses were performed using Mann-Whitney test, chi-square test and Kaplan-Meier method. Fourteen LS patients (group A) had SIADH at presentation. Group B consisted of 230 LS patients without SIADH. There were more patients with poorer performance status (ECOG 2-4) in group A than B (28.6% versus 7.8%, P=0.03). Otherwise, sex, age at diagnosis, nodal spread, pleural effusion, bronchial obstruction, superior vena cava obstruction, performance status, weight loss, and lactic dehydrogenase at presentation, were comparable between the two groups. Treatments given, e.g., extent of surgical resection (if performed, whether complete/incomplete), total number of chemotherapy cycles, radiotherapy doses, were comparable (P>0.05). The response to chemo-radiation was not significantly different (P=0.7). Five-year overall survival (8% versus 19%, P=0.08), and cause-specific survival (16% versus 20%, P=0.13) showed that group A patients had a worse outcome, though of borderline significance. Symptoms related to SIADH included: weakness, 4 patients; tiredness, 3; change in level of consciousness, 1; seizure, 1. The range of lowest sodium level was 110-129. Two patients also had paraneoplastic myopathy. SIADH resolved in 12 patients at 1.6-44.7 weeks (median: 4.3). Among the 14 patients who initially presented with SIADH and recurred later, 10 had recurrence of SIADH at the time of tumor recurrence. Serum sodium was useful for post-treatment surveillance in SCLC patients who presented with SIADH, with 71% (10/14) developing SIADH again at the time of recurrence. SIADH is a poor prognostic factor for LS SCLC.

Management of the syndrome of inappropriate antidiuretic hormone secretion in small cell lung cancer

From 1976 to 1980, 18 of the 250 patients (7%) seen with small cell carcinoma of the lung had clinically evident inappropriate secretion of antidiuretic hormone (ADH). Hyponatremia was usually severe (116 +/- 7 meq/l), and eight patients showed symptoms of water intoxication at the time of diagnosis. Of the eight patients who had plasma ADH measured at diagnosis, seven had elevated values (mean 52.0, range 16.1 - greater than 250 pg/ml). Intensive combination chemotherapy produced objective tumor responses in all patients, and syndrome of inappropriate ADH secretion (SIADH) resolved in 16 of 17 evaluable patients within three weeks of initiation of treatment. ADH values after therapy were normal, and all patients maintained a normal serum sodium during the period of tumor remission in spite of unrestricted fluid intake. All 17 evaluable patients have developed progressive cancer, but only 10 have manifested recurrent SIADH. Patient survival was similar to the overall population of small cell carcinoma patients without SIADH. The indirect methods of treatment for SIADH (fluid restriction, demeclocycline, lithium, urea) are frequently of transient value while awaiting a response to chemotherapy or in patients with resistant tumors. However, the initial treatment of choice for SIADH associated with small cell carcinoma of the lung is combination chemotherapy.

Endocrine function in small cell undifferentiated carcinoma of the lung

The endocrine status of 106 patients with undifferentiated small cell carcinoma of the lung was evaluated before treatment was begun. Almost one half of the patients had evidence of abnormal control of the secretion of adrenal cortical steroids, manifested by loss of diurnal rhythmicity or dexamethasone suppressibility. Only two had the clinical syndrome of ectopic ACTH secretion. Evidence of inappropriate secretion of vasopressin was found in 38% of the patients, most of whom also had abnormalities of corticosteroid secretory pattern. About one half of the patients had evidence of abnormal glucose tolerance, and many also had a paradoxical rise of plasma growth hormone concentration after glucose administration. The levels of the other hormones studies were normal. The pattern of hormone abnormality observed in these patients appears to be relatively specific for small cell undifferentiated carcinoma, and is different from that observed in other pulmonary tumors. Patients with abnormal control of plasma cortisol had a worse prognosis than those with normal adrenal function, largely because of decreased response rates to chemotherapy. Other endocrine abnormalities were of no prognostic significance.

The pattern of ectopic hormone production in lung cancer

Pulmonary cancers produce many hormonal polypeptides. There is a tumor-specific pattern to the appearance of abnormal adrenal function and inappropriate secretion of vasopressin, which are frequently found in small cell undifferentiated carcinoma but occur only very rarely, if at all, in squamous tumors. Humoral hypercalcemia, on the other hand, occurs almost entirely in squamous tumors and is rarely if ever seen in small cell or large cell tumors or in adenocarcinoma. In contrast, "big ACTH" and beta lipotropin are found in the plasma and tumor extracts of lung cancers of all types. Calcitonin and the beta chain of human chorionic gonadotropin are also found in the plasma of a considerable portion of patients with all histological types of lung cancers.

Small cell carcinoma of the lung

Over a 5-year period 230 cases of small cell carcinoma presented to Brompton Hospital, London. The male to female ratio was 2.5:1 and 39% had evidence of extrathoracic disease. Forty-five patients were untreated and had a median survival of 70 days. The 5-year survival for surgery and radiotherapy was 6.6% and 4.2% respectively. Of 13 patients treated with chemotherapy the median survival was 285 days. The factors which influence survival are described.